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Std 10 History Chapter 5 Question Answer Mass Media and History Maharashtra Board

Balbharti Maharashtra State Board Class 10 History Solutions Chapter 5 Mass Media and History Notes, Textbook Exercise Important Questions and Answers.

Class 10 History Chapter 5 Mass Media and History Question Answer Maharashtra Board

History Class 10 Chapter 5 Question Answer Maharashtra Board

Question 1.
(A) Choose the correct option from the given options and complete the statement.

(1) The first English newspaper in India was started by ………………………….. .
(a) James Augustus Hickey
(b) John Marshall
(c) Allen Hume
Answer:
(a) James Augustus Hickey

(2) Television is an ………………………….. medium.
(a) visual
(b) audio
(c) audio-visual
Answer:
(c) audio-visual

(B) Identify and write the wrong pair in the following set.
(1) ‘Prabhakar’ – Acharya P.K. Atre
(2) ‘Darpan’ – Balshastri Jambhekar
(3) ‘Deenbandhu’ – Krishnarao Bhalekar
(4) ‘Kesari’ – Bal Gangadhar Tilak
Answer:
(1) Wrong Pair: ‘Prabhakar’ – Acharya P.K. Atre

Mass Media And History Class 10 Question 2.
Write short notes :
(1) The role of newspaper in the Indian struggle for independence
Answer:
Newspapers played an important role in the Indian independence struggle. It is as follows

• Newspapers served as an important medium to create awareness during those times.
• They described greatness of Indian culture and history to gather support of masses for the freedom movement.
• They supported social, political and religious movements and opposed imperialism.
• They discussed various social and political issues.
• The ideas of social reformers and various organisations active in independence struggle reached people through newspapers.

(2) Why do we need mass media?
Answer:
Mass media includes print and electronic and various new media.

• It facilitated free flow of information to all strata of the society and brought the world closer.
• Editorials, various columns and supplements are essential parts of newspapers.
• Readers also get a platform to voice their opinions. In fact, newspapers can help to make democracy stronger.
• Akashrani broadcasted various programmes of the government as well entertainment.
• Awareness creating programmes. It fulfill the need of the government to connect with people.
• Television is an Audio-Visual medium which has made it possible to cross the inherent limitations of newspapers.
• Radio to show the actual visuals of an event to people.
• Mass Media is very important as it plays an important role to strengthen democracy.

(3) Mass Media and professional opportunities.
Answer:
There are many professional opportunities available in printed, electronic and digital media.

• Writers, columnists, editors are required to write articles, columns and editorials in news-papers.
• Newspapers also require reporters to gather news and technicians to work in the press.
• There is requirement of actors and technicians in electronic media.
• Artists are required to present programmes on television, in the same way news presenters, anchors are required.
• If the articles, columns and programmes are based on history, an expert in history is required.

Mass Media And History Class 10 Question Answer Question 3.
Explain the following statements with reasons.
(1) Any information received through mass media needs to be reviewed critically.
Answer:

• Information provided in the media may not represent the exact truth. We need to scan it carefully.
• We have to understand idealistic and investigative motives of newspapers, government policies and prevailing social conditions behiid the newspiece.
• The information received through Mass Media might be prejudiced or give a one-sided idea.
• ‘Stern’, a German weekly magazine, purchased and published a number of so called handwritten diaries of Hitler.
• It then sold them to a number of publication companies.
• However, later it was proved that those diaries were forged. Hence it is essential to verily the information received through Mass Media.

(2) Knowledge of history is essential for newspaper articles.
Answer:

1. In order to unfold the background of an event in the news, we have to resort to history.
2. Some columns are based on historical events. These columns provide historical information about economical, social and political events in the past.
3. Newspapers publish supplements in addition to the regular edition or special issues to mark the completion of 50 or 100 years of an event. On such occasions, one has to review history of that particular event.
4. Even while writing columns like what happened in history on this day it is necessary to know past event. Hence, the knowledge of history is essential for writings of such type.

(3) Television is the most popular medium.
Answer:

• Television being an audio-visual medium brings us into contact with events in an exciting and clarifying way.
• It crossed the inherent limitations of newspapers and radio to show actual visuals.
• It becomes possible for people to watch all the national and international events sitting at home.
• Social problems, discussion on education and economics and political events are viewed by people.
• In 1991, Indian government granted permission to private, national and international channels to telecast in India.
• Television became a treasure house of entertainment.

Therefore, the television is the most popular medium.

Class 10 History Chapter 5 Questions And Answers Ssc Board Question 4.
Read the following extract and answer the questions.
Radio: ‘Indian Broadcasting Company’ (IBC), a private radio company was the first one to broadcast daily programmes. Later the same company was taken over by the British Government and named as, ‘Indian State Broadcasting Service (ISBS). On 8th June 1936 it was renamed, as ‘All India Radio (AIR)’.

After Independence, AIR became an integral part of the Ministry of Information and Broadcasting (India). Initially, it broadcasted Governmental programmes and schemes. It was named as ‘Akashvani’ on the suggestion of the famous poet Pandit Narendra Sharma. Akashvani broadcasts various entertainment, awareness creating and literary programmes. It also broadcasts special programmes for farmers, workers, the youth and women. The ‘Vividh Bharati’ programmes are broadcasted in 24 regional languages as well as 146 dialects of Indian languages. Lately, various new channels like ‘Radio Mirchi’ are providing radio services.

(1) Akashavani (AIR) is an integral part of which ministry?
Answer:

1. Indian Broadcasting Company, a private radio company was taken over by the British Government in 1927 and named ‘Indian State Broadcasting Service (ISBS)’. On 8th June 1936, it was renamed as ‘All India Radio (AIR)’.
2. AIR became integral part of the Ministry of Information and Broadcasting after independence. It was renamed Akashvani on the suggestion of Pandit Narendra Sharma.
3. Initially it used to broadcast Government’s programmes and schemes. Later it started broadcasting various entertainment, awareness creating and literary programmes.
4. Akashvani started ‘Vividh Bharati1 programmes. It broadcasts special programmes for farmers, workers, the youth and women.
5. Vividh Bharati Programmes are broadcast in 24 regional languages and 146 dialects.

(2) What was the new name of IBC?
Answer:
Indian Broadcasting Company (IBC) was taken over by the British Government. It was named as the Indian State Broadcasting Services. (ISBS). On 8th June 1936, it was renamed as ‘All India Radio’ (AIR).

(3) In how many regional languages and local dialects are ‘Vividh Bharati’ programmes broadcasted?
Answer:
People get access to news through social media like Twitter, Instagram, Facebook, YouTube and from web news portals, web channels. This information is available in English and many other languages.

(4) How AIR was named ‘Akashavani’?
Answer:
AIR was named as Akashvani on the suggestion of the famous poet Pandit Narendra Sharma.

Question 5.
Complete the following concept chart.

Answer:

Project
Write a review of a historical serial that you have watched.

Memory Map

Question 6.
Complete the sentences by choosing a correct option:
(a) ………………….. is the first newspaper in Marathi.
(a) Deenbandhu
(b) Prabhakar
(c) Darpan
(d) Kesari
Answer:
(c) Darpan

(b) 6th January is celebrated as ………………….. day in Maharashtra.
(a) Periodical Day
(b) Newspaper Day
(c) Printing Day
(d) Journalist Day
Answer:
(d) Journalist Day

(c) The letters ‘Shatpatre1 published in Prabhakar were written by ………………….. .
(a) Lokmanya Tilak
(b) Lokhitvadi
(c) Mahatma Gandhi
(d) Justice Ranade
Answer:
(b) Lokhitvadi.

(d) The honour of printing illustrations for the first time in an Indian newspaper goes to ………………….. .
(a) Dnyanoday
(b) Darpan
(c) Prabhakar
(d) Kesari
Answer:
(a) Dnyanoday

(e) Deenbandhu was started by ………………….. who was a close associate of Mahatma Phule.
(a) Dr. Babasaheb Ambedkar
(b) Lokmanya Tilak %
(c) Narayan Meghaji Lokhande
(d) Krishnarao Bhalekar
Answer:
(d) Krishnarao Bhalekar

(f) ………………….. newspaper was started by Agarkar and Lokmanya Tilak.
(a) Deenbandhu and Induprakash
(b) Darpan and Prabhakar
(c) Dnyanoday and .Digdarshan
(d) Kesari and Maratha
Answer:
(d) Kesari and Maratha

(g) Balshastri Jambhekar started ………………….. the first monthly magazine in Marathi.
(a) Digdarshan
(b) Prabhakar
(c) Darpan
(d) Dnyanoday
Answer:
(a) Digdarshan

(h) ………………….. was acknowledged as the fourth pillar of democracy.
(a) Representatives
(b) Periodicals
(c) Newspaper
(d) Books
Answer:
(c) Newspaper.

(i) The first English news bulletin was broadcast on 23rd July, 1927 from the …………………… radio station.
(a) Kolkata
(b) Madras
(c) Mumbai
(d) Dblhi
Answer:
(c) Mumbai

(j) Dr. Rajendra Prasad, the first President of India inaugurated the …………………… Doordarshan centre.
(a) Mumbai
(b) Bangalore
(c) Lucknow
(d) Delhi
Answer:
(d) Delhi

(k) Newspapers published special supplements or a special issue to commemorate occasions like completion of seventy-five years of …………………… in 2017.
(a) Khilafat Movement
(b) Non Co-operation Movement
(c) Civil Disobedience Movement
(d) Quit India Movement
Answer:
(d) Quit India Movement

(l) ……………………, a German weekly magazine, had purchased a number of so called handwritten diaries that were later proved forged.
(a) Time Magazine
(b) Statesman
(c) Stern
(d) Reuters
Answer:
(c) Stern

(m) Akashvani has preserved recordings of all speeches delivered by the …………………… on 15th August.
(a) President
(b) Wee President
(c) Prime Minister
(d) Army General
Answer:
(c) Prime Minister

(n) Akashwani comes under the Ministry of …………………… of the Indian Government.
(a) Social welfare
(b) Human Resource and Development
(c) Information and Broadcasting
(d) Education Technology
Answer:
(c) Information and Broadcasting.

Question 7.
Identify the wrong pair in the following and write it:

Answer:
Wrong pair: Prabhakar – Acharya R K. Atre

(2)

Answer:
Wrong pair Deenbandhu – Information on Telegraph

(3)

Answer:
Wrong pair: Digdarshan – Narendra Sharma

Question 8.
Do as directed:
(a) Complete the graphical description

Answer:

(2)

Answer:

(b) Show the progress of Indian television Time-line:

Answer:

Question 9.
Explain the following concepts:

(a) Electronic or Digital Journalism or Web Journalism.
Answer:

1. In the modem times, the computer and internet have become indispensable parts of printing and publishing process. Computer technology has led to the widespread practice of digital journalism.
2. Websites run by newspapers are basically extensions of newspapers themselves. Modern periodicals are part of electronic or digital journalism.
3. People get access to news through social media like Twitter, Instagram, Facebook, YouTube and from web news portals, web channels. This information is available in English and many other languages.
4. Journalists working in this area today have to have many more skills than in the past when writing was the only requirement. Information available on these mediums should be reviewed critically and used with utmost care.

(b) E-newspapers
Answer:

1. In recent times, e-newspapers have got prominent place in mass media.
2. E-newspaper is not exactly like the printed one. In e-newspapers, news comes in sequence and not based on the nature and the importance of the news, like in printed newspaper e.g.. Front page news. Headline or Last page news.
3. The news which we want to read has to be clicked and then it appears on the screen in detail.
4. There is space provided for opinion of readers. In 1992, the first edition of the e-newspaper was published by ‘Chicago Tribune1.
5. At present, almost all newspapers are available as e-newspapers and people can read them anytime, anywhere using the Internet or computer, tab, laptop or mobile.
6. In recent times many newspapers have introduced e-newspapers. The e-newspapers are being received well by the readers.
7. Learn to read e-newspapers with the help of your teachers.

Question 10.
Write short notes:
(a) Bengal Gazette:
Answer:

• Bengal Gazette is the first newspaper which was started in India.
• It was started by James Augustus Hickey, an Irish national.
• It was first published on 29th January, .1780. It was also called “Calcutta General Advertiser’.
• Bengal Gazette laid the foundation of newspaper in India.

(b) News printed in ‘Darpan’:
Answer:
The ‘Darpan newspaper started by Balshastri Jambhekar printed all types of news like political, economic, social and cultural. Some of them are mentioned below:

• The Accounts of Expenditure from the Three Administrative Divisions of the East India Company.
• The Danger of Russian Attack on the Nation.
• Appointment of a Committee for Cleanliness of the City.
• Remarriage of Hindu Widows.
• The Inception of Theatre at Calcutta.
• Achievements of Raja Ram Mohan Roy in England. All these reports published in the paper throw light on various situations/events of those days.

(c) Television:
Answer:

• The first President of India, Dr. Rajendra Prasad inaugurated Delhi Doordarshan Centre.
• Mumbai Doordarshan started to telecast its programmes on 2nd October, 1972.
• Colour television started on 15th August, 1982. The Indian government granted permission to private, national and international channels in 1991 to telecast in India.

Question 11.
Explain the following sentences with reason:
(a) Newspaper is an important medium of education and information.
Answer:

• Newspapers report events which are interesting to the public. But the importance of newspaper stretches far beyond a passing humari interest in events.
• It covers a miscellany of topical issues. News would involve matters of higher importance like war, global warming, education, national elections or trivial issues such as scandals, gossips and debates on minor controversies.
• Newspapers have contributed significantly to the spread of literacy and the concept of human rights and democratic freedoms.
• They are integral to the development of democracy. In fact, they can help in making the democracy stronger.
• Newspapers not only report the events but continue to shape opinions in the global village.

(b) 6th January is observed as ‘Patrakar Din’ or ‘Journalist Day’ in Maharashtra.
Answer:

• Balshastri Jambhekar started the first newspaper in Marathi on 6th January, 1832 in Mumbai.
• He is referred to as the ‘First Editor’ as he was the first editor.
• He laid the foundation of Marathi newspaper by starting Darpan. As 6th January is his birth date, it is observed as ‘Patrkar Din’ or ‘Journalists’ Day’ in Maharashtra.

(c) Television and history are closely related.
Answer:

1. Television plays a major role in developing interest in history. While producing shows and serials based on history and mythology, it is essential to have an accurate knowledge of history and know the minute details.
2. ‘Bharat Ek Khoj’, Raja Shivchhatrapati, Ramayana, Mahabharata are among the few popular serials based on history and mythology. While producing these serials.
3. It was essential to know the prevalent social conditions, outfits, lifestyle, weaponry, lingual expressions of the people. Historians who had knowledge on these subjects are required.
4. While making programmes, based on sportsmen, literature, war, historical events, forts and animal life, it is important to give history of their development in that particular period.
5. While conducting discussions on television on topics like social problems, education, economics, health, it is important to give references from the past.

This shows that the knowledge of history is required in the making many of programmes on Television. Hence Television and history are closely related.

Question 12.
Answer the following question in 25-30 words:
(a) Explain the objectives of newspapers.
Answer:
The main objectives of newspapers are as follows:

• Newspapers provide various local, national and international news to the people and inform them about daily events.
• They narrate political, economic, cultural and social history of the country.
• Newspapers fulfill their role as the fourth column of democracy by creating public awareness and becoming a medium of mass education.
• They even condemn the anti-social elements in the society and support the weaker section.

(b) How is history helpful in the planning of the Akashvani programmes ?
Answer:
Akashvani broadcasts all types of programmes from celebration of independence day to entertainment programmes. In planning these programmes, the knowledge of history is essential.

1. Akashvani invites historians as experts for discussions while presenting programmes on various occasions such as the anniversaries of births and deaths of national leaders, anniversaries of historical events; speeches of all Prime Ministers/Presidents.
2. Programmes like ‘On This Day in History’ is a daily programme which highlights importance of that day and date in history.
3. Information has to be verified by historians before it reaches the people. Lectures on the contributions of various national leaders need to be supported by historical information. In the following ways history is helpful in the planning of Akashvani programmes.

(c) How were the message conveyed to the people in olden days?
Answer:
The following were a few means used to convey messages to the people in olden days:

• A town crier would run on the streets beating drums and crying out important news according to the orders of the king.
• So, the news would spread among people by word of mouth.
• Inscriptions with royal decrees were placed at public places.

Question 13.
Read the following passages and answer the questions:”
(a) Which programmes are broadcasted by Akashvani?
Answer:

• Initially, Akashvani broadcasted government programmes and schemes.
• Later it broadcasted various entertainment and literary programmes.
• Akashvani presents various programmes for creating awareness.
• Special programmes are also broadcasted for farmers, workers, youth and women.

(a) On which book is the serial ‘Bharat Ek Khoj’ based on?
Answer:
The Serial Bharat Ek Khoj is based on ‘Discovery of India’, a book written by Pandit Jawaharlal Nehru.

(b) Who directed the serial ‘Bharat Ek Khoj’?
Answer:
The serial was directed by Shyam Benegal.

(c) Which factors/aspects of Indian history are depicted in ‘Bharat Ek Khoj’? OR Why was ‘Bharat Ek Khoj’ a serial telecasted by Doordarshan admired in all parts of India?
Answer:
The television serial ‘Bharat Ek Khoj’ presented social, political and economic life from ancient to the modem period in India.

1. It portrayed various aspects of Indian history like Harappan civilisation, Vedic history and the interpretation of epics like Mahabharata and Ramayana.
2. It used the technique of dramatisation effectively to recreate the Mauryan period and show the impact of Turk-Afghan invasions.
3. The Mughal period and their contributions which have long-lasting effect on social and cultural fabric of India is shown. The rise of Bhakti movement, role of Chhatrapati Shivaji Maharaj in getting swarajya is portrayed.
4. The last episodes (finale) of the serial narrate social movements and India’s freedom struggle in modem period.

Thus, the serial effectively portrayed the journey of India from Harappan civilisation to the modern period and therefore was admired in all parts of India.

Question 14.
Answer the following questions in detail:
(a) What were the different means of communication known around the world before the advent of newspaper?
Answer:
The following means of communication were used to convey news before the advent of newspaper:

1. Inscriptions with royal decrees placed at public places was a custom in Egypt. Emperor Ashoka followed the sam method to reach out to his subjects.
2. In the Roman Empire, roytil decrees were written on papers and those were distribute’d in all regions. It also contained information of various events taking place in the nation and its capital.
3. During, the reign of’ Julius Caesar ‘Acta Diurna’, meaning acts of everyday used to be placed at public places in Rome.
4. In the 7th century C.E., in China, royal dictates were distributed among people at public places.
5. In England handouts were distributed occasionally among people at public places giving information about war or any important events.
6. Travellers arriving from different faraway places would add spice to stories from those places and narrate the same to local people. The ambassadors of a king posted at various places would send back important news to the royal court.

(b) Write information on Periodicals based on its types.
Answer:
Magazines and journals which are published at regular intervals are known as Periodicals.
Types:

• They are categorised as weekly, biweekly, monthly, bimonthly, quarterly, six monthly and annual.
• There are some chronicles which are published at no fixed time.

Classification: Periodicals can be classified as popular and scholarly.

• If a periodical aims at specialists and researchers, it is a ‘journal1. Articles are generally written by experts in the subject.
• Popular periodicals are magazines published with variety of content. They can be on fashion, sports, entertainment and films.
• Bharatiya Itihas ani Sanskruti and Marathwada Itihas Parishad Patrika are periodicals of present times. Periodicals are an important source to study history.

(c) Write about the important role of newspaper in the freedom struggle.
Answer:

1. The press was the chief instrument for carrying out the political tasks and propagation of nationalist ideology.
2. Both English and Vernacular press started by prominent “leaders like Gopal Ganesh Agarkar and Lokmanya Tilak acted as catalyst to the freedom struggle. They started ‘Kesari’ and ‘Maratha’ in 1881.
3. Newspapers played a great role in building up an increasingly strong national sentiment and consciousness among people. It was an instrument to arouse, train, mobilise and consolidate nationalist public opinion.
4. The newspapers were an effective tool in the hands of social reformers. They exposed social evils such as child marriage, ban on remarriage of the widows, inhuman institution as untouchability, caste fetters, etc. It became a weapon in their hands to educate masses.
5. A comparative study was presented in newspaper on western education, knowledge and national education.
6. Newspapers also discussed political institutions in India and the west. The main aim of these newspapers was not to gain profit but to serve the people.

(d) Give a short account of the development of Indian television.
Answer:

1. Television service started in India in 1959. Dr. Rajendra Prasad, the first Indian President, inaugurated the Delhi Doordarshan centre.
2. Mumbai centre began to telecast its programmes on 2nd October 1972. Colour television was introduced in India on 15th August 1982.
3. The national telecast began in 1983. Doordarshan started Channels like DD Sports, DD Metro, news, etc. along with 10 regional channels.
4. In the year 1991, the Indian government gave permission to private, national and international channels to telecast in India.
5. Presently there are more than 800 national and regional channels. Some of them are exclusive news, sports, music, movies and religious channels which telecast programmes 24 hours a day.

(e) Distinguish between Newspapers and Magazines.
Answer:
Newspapers and magazines differ in their format, objectives and duration of getting published. The differences are noted below:

Brain Teaser

Across:

• Referred to as the ‘First Editor’.
• A newspaper representing masses of the Indian society (Bahujan Samaj).
• Tryambak Shankar Shejwalkar edited this journal.
• Letters by Lokhitvadi.

Down:

• The history of French Revolution was published in this newspaper.
• Newspaper started by James Augustus Hickey.
• First monthly magzine in Marathi.
• Pandit Narendra Sharma suggested this name for AIR.

Class 10 History Textbook Solutions Answers

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Std 10 History Chapter 1 Question Answer Historiography Development In The West Maharashtra Board

Balbharti Maharashtra State Board Class 10 History Solutions Chapter 1 Historiography Development in the West Notes, Textbook Exercise Important Questions and Answers.

Class 10 History Chapter 1 Historiography Development In The West Question Answer Maharashtra Board

History Class 10 Chapter 1 Question Answer Maharashtra Board

Question 1.
(A) Choose the correct option from the given options and complete the statement.
(1) It may be said that …….. was the founder of modern historiography.
(a) Voltaire
(b) Rene Descartes
(c) Leopold Ranke
(d) Karl Marx
Answer:
(a) Voltaire

(2) ………… wrote the book entitled ‘Archaeology of Knowledge’.
(a) Karl Marx
(b) Michel Foucault
(c) Lucien Febvre
(d) Voltaire
Answer:
(b) Michel Foucault

(B) Identify and write the wrong pair in the following set.
(1) Georg Wilhelm Friedrich Hegel – ‘Reason in History’
(2) Leopold von Ranké – ‘The theory and Practice of History’
(3) Herodotus – ‘The Histories’
(4) Karl Marx – ‘Discourse on the Method’
Answer:
(1) Right pair: Georg Wilhelm Friedrich Hegel – ‘Reason in History’
(2) Right pair: Leopold von Ranké – ‘The theory and Practice of History’
(3) Right pair: Herodotus – ‘The Histories’
(4) Wrong pair: Karl Marx – Discourse on the Method.

Question 2.
Explain the following concepts.
(1) Dialectics
Answer:

• In order to understand the true nature of an event, one needs to know its opposite for e.g. True — False, Good — Bad, etc.
• A German philosopher, Georg Wilhelm Friedrich Hegel had put forward this method of analysis of history.
• A theory called ‘Thesis’ is proposed at the beginning. It is followed by another theory called Antithesis’ which is, contrary to ‘Thesis’.
• After a thorough logical discussion of both new thesis is proposed having gist of both (Thesis and Antithesis).
• This process of orriving at a new thesis is called Synthesis.
• This method of analysis of history which is based on opposites is known as ‘Dialectics’.

(2) Annales School
Answer:

• At the dawn of the twentieth century, the writing ¿f history got a new direction.
• Along with political events, kings, great leaders, the study of climate, local people, agriculture, trade, technology, means of communication, social divisions and their collective psychology of a group was also considered important in the study of history.
• This new school of thought is known as Annales School. Annales School was started by French historians.

Question 3.
Explain the following with its reason.
(1) Historical research was driven to focus in depth on various aspects of women’s life.
Answer:

• Initially, there was a lot of dominance of male perspective on historical writing. Simone de Beauvoir, a French scholar, insisted on inclusion of women perspective in historiography.
• She emphasised on the inclusion of women in the process of writing history.
• She insisted on rethinking of the male dominated perspective of history.
• Because of her efforts historical research was driven to focus in depth on various aspects of women’s lives their employment, their role in trade unions, institution working for their cause, and their family life.

(2) Foucault called his method, ‘the archaeology of knowledge’.
Answer:

• According to Michel Foucault, the prevailing method of arranging historical events in a chronological order was not right.
• He threw light on the fact that archaeology does not strive to reach the ultimate historical truth.
• It attempts to explain various transitions in the past.
• Foucault gave more importance for explaining the transitions in history. Hence, his method is called ‘the archaeology of knowledge’.

Question 4.
Complete the concept chart.

Answer:

Question 5.
Answer the following in detail.
(1) Explain Karl Marx’s ‘Class Theory’.

Answer:
In the latter part of nineteenth century, German thinker, Karl Marx put forward ‘Class Theory’ in his book ‘Das Kapital’.

According to him:

1. History i not about abstract ideas but living people. The fullillment of basic needs of people depends on the nature of prevalent means of production and the ownership.
2. All the different strata of the society do not get equal access to these means of production which causes the division of the society into classes. It rešults into class struggle.
3. The class which owns means of production $ economically exploits the rest of the classes. Human history, according to him, is the history of class struggle.

(2) What are the four characteristics of modern historiography?
Answer:
The following are the four characteristics of modern historiography:

1. Its method is based on scientific principles and begins with formation of relevant questions.
2. These questions are anthropocentric i.e. they are about ancient human societies and their deeds in that period of time. No interrelation between the divine and human needs is suggested.
3. Answers to these questions are supported by reliable evidence and they are presented in a logical order.
4. History presents a graph of man’s progress with the help of his deeds in the past.

(3) What is feminist historiography?
Answer:

• Feminist historiography means writing history with women perspective. There was a lot of dominance of male perspective on historical writing.
• Simone de Beauvoir, a French scholar, insisted on rethinking on the male dominated perspective and including the women’s perspective in historiography.
• The idea of feminist historiography was accepted.
• Because of her efforts various aspects of women’s lives like their employment, their role in trade unions and their family life became part of historiography.

(4) Explain Leopold von Ranké’s perspective of history?
Answer:
Leopold’s view on ways to write history throws light on his perspective of history:

1. He spoke about the critical method of historical research. He gave importance to information gathered through original documents.
2. He also stated that all types of original documents related to the historical event should be examined in detail and with great care.
3. He believed that with this method it was possible to reach the historical truth. He was critical of imagination in narration of history.

Historiography : Development In The West Questions And Answers Pdf Project
Obtain detailed information on your favourite subject and write its history. For example :
– History of Pen
– History of Printing technology
– History of Computers
Answer:

Memory Map

Question 6.
Choose the correct option from the given options and complete the sentences:

(a) A scholar who writes critical historical narratives is known as ………………………… .
(a) an archaeologist
(b) a historian
(c) a social scientist
(d) a language expert
Answer:
(b) a historian

(b) The earliest inscription in the world is displayed at Louvre museum in ………………………… .
(a) England
(b) France
(c) Germany
(d) Portugal
Answer:
(b) France

(c) The tradition of recording historical events can be traced back to ………………………… civilization in Mesopotamia.
(a) Sumer
(b) Egyptian
(c) Arab
(d) Mohenjodaro
Answer:
(a) Sumer

(d) The tradition of modern historiography has its roots in the writings of ………………….. historiAnswer:
(a) Roman
(b) Greek
(c) German
(d) French
Answer:
(b) Greek

(e) ………………….., a Greek historian of the fifth century B.C.E., had used the term ‘History’ for the first time for his book entitled, ‘The Histories’.
(a) Leopold Ranke
(b) Georg Hegel
(c) Michel Foucault
(d) Herodotus
Answer:
(d) Herodotus

(f) In 1737 C.E., the ………………….. university in Germany had an independent department for history.
(a) Oxford
(b) Cambridge
(c) Gottingen
(d) Stanford
Answer:
(c) Gottingen

(g) Historiography of the nineteenth century was greatly influenced by the thoughts of …………………..
(a) Karl Marx
(b) Voltaire
(c) Georg Hegel
(d) Leopold von Ranke
Answer:
(d) Leopold von Ranke

(h) A new school of historiography arose in France known as ………………….. school.
(a) Translation
(b) Annales
(c) Nationalism
(d) Communist
Answer:
(b) Annales

(i) The method of analysis which is based on opposites is known as …………………. .
(a) Numismatics
(b) Arithmetic
(c) Polynomial
(d) Dialectics
Answer:
(d) Dialectics

(j) ………………….. considered subjects like psychological disorders, science of medicine, prison administration for historical analysis.
(a) Michel Foucault
(b) Leopold Ranke
(c) Karl Marx
(d) Voltaire
Answer:
(a) Michel Foucault

(k) After 1990, ………………….. were considered as an independent social class.
(a) labourers
(b) women
(c) men
(d) farmers
Answer:
(b) women

(l) According to ………………….., historical realities should be presented in a logical manner.
(a) Georg Hegel
(b) Voltaire
(c) Simone de Beauvoir
(d) Herodotus
Answer:
(a) Georg Hegel

(m) According to ………………….., one should never accept anything as the truth till all the doubts are solved.
(a) Rene Descartes
(b) Karl Marx
(c) Voltaire
(d) Herodotus
Answer:
(a) Rene Descartes.

Question 7.
Identify the wrong pair in the following and write it:
(1)

Answer:
Wrong pair: Karl Marx – Discourse on the Method.

(2)

Answer:
Wrong pair: Simone de Beauvoir Germany.

(3)

Answer:
Wrong pair: History is not about abstract ideas but about living people – René Descartes.

Question 8.
Complete the concept chart

Answer:

Answer:

Question 9.
Prepare a flow chart on the given topic:
Stages of historiography
Answer:

Question 10.
Write short notes:
(1) Georg Wilhelm Friedrich Hegel:
Answer:

• Georg Hegel was a German philosopher.
• He was of the view that the historical realities should be presented in a logical manner. According to him, Timelme was indicative of progress.
• He believed that presentation of history is bound to change as time passes because new evidence surfaces.
• His philosophy convinced many scholars that historical methods were not of lesser quality, though they differed from the scientific method.
• His lectures and articles are published in a book called ‘Encyclopaedia of Philosophical Sciences’.
• His book ‘Reason in History’ is well known. He devised a method of analysis based on opposites known as Dialectics’.

(2) Karl Marx:
Answer:

1. Karl Marx was a German thinker in the nineteenth century. He wrote the world famous treatise Das Kapital’. According to him, history was not about abstract ideas but about living people.
2. He believed that human relationships are shaped by the fundamental needs of people and the ownership of prevalent ineczns of production to meet those needs.
3. He stated that unequal accessibility to the means of production creates à division in socièty leading to class struggle. His theory of class struggle is considered significant all over the world.
4. According to Marx, human history is the history of class struggle because the class which owns the means of production economically exploits the rest of the classes.

(3) Michel Foucault:
Answer:

• Michel Foucault was a twentieth century historian from France.
• He wrote the book ‘Archaeology of Knowledge’.
• In this book, he insisted that the prevailing practice of arranging historical events in a chronological order is not right.
• He gave importance to explaining the transitions that took place in history.
• He acknowledged the role of subjects such as science of medicine, psychological disorders, prison.
• Administration in historical analysis. This was not acknowledged by earlier historiAnswer:

(4) Leopold von Ranke:
Answer:

1. Leopold von Ranke, a German philosopher, laid emphasis on utmost importance of information gathered through original documents.
2. In order to reach historical truth, it was necessary to examine all documents related to historical event. He critcised the imaginative narration of history.
3. Collection of his articles are published in two books, entitled ‘The Theory and Practice of History’ and ‘The Secret of World History’.
4. Ranke had great influence on historiography of nineteenth century.

Question 11.
Give reasons:
(a) In historical research, it may not be possible to use the method of experiments and observation.
Answer:

1. In physical and natural sciences, experiment and observation method is used to establish laws that remain true irrespective of the time and space.
2. These laws can be tested and proved again and again.
3. In historical research, the events had already taken place in the past and we were not present in the historical time and space.
4. Moreover, these events cannot be recreated in the present time and space. Hence, experiment and observation method may not be used in historical research.

(b) Historiography in the 18th century gave importance to objectivity in history.
Answer:

• A remarkable progress was achieved in the fields of Philosophy and Science till the eighteenth century in Europe.
• It was believed that by applying scientific methods it was possible to study social and historical truths.
• In the later period, history and historiography witnessed a lot of philosophical discussion.
• This eliminated the imaginative and divine context in history and gave importance to objectivity.

Question 12.
Answer the following in 25-30 words:
(a) What is Historiography?
Answer:

1. The writing of critical historical narrative is called Historiography. A person who writes it is known as ‘Historian’. The following steps are helpful in writing historical narrative:
2. Information related to history is collected and analyzed.
3. The various sources are critically examined to understand the references regarding time and space in the given information as well as the conceptual framework used.
4. After examining the references of historical information, relevant questions related to these historical references are framed and hypotheseis are formulated.
5. In short, writing of critical historical narrative by following this method is known as historiography.

(b) What did Rene Descartes insist upon?
Answer:
French Philosopher Rene Descartes insisted on the following in writing historiography:

1. ‘Never to accept anything as true till all grounds of doubt are excluded’.
2. Hence, the reliability of a source like historical documents should be verified by critically examining them while writing history.

(c) Why is Voltaire said to be the founder of modern historiography?
Answer:
Voltaire, a french scholar, opined that it was important to consider the following aspects while writing history:

1. objective truth and chronology of events;
2. prevalent social traditions, agriculture, trade and economic system. It was because of his view that all aspects of human life was considered for history writing. Therefore, he is said to be the founder of modern historiography.

(d) What are the objectives of writing history?
Answer:
History is researched and written down with following objectives:

• To analyse the events in the past.
• To verify information about the historical events and their interconnections.
• To study in detail and remove imaginative element and bring forth the truth.
• To put the past events in chronological order.

(e) What progress was achieved in historiography in the eighteenth century?
Answer:
The following progress was achieved in historiography in the eighteenth century:

• Scientific methods were applied to study social and historical truths.
• Philosophical discourses revolving around divine phenomena were given less importance.
• Philosophical discussions focused more on the objectivity in history and historiography.
• Since the universities got an independent department of history, they became centres of historical studies.

Question 13.
Head the given passage carefully and answer the questions given below:
(a) Who is called a Historian?
Answer:
A scholar who writes critical historical narratives is called a Historian.

(b) Complete the concept chart.
Factors which determined historian’s

Answer:
Factors which determined historian’s

(c) How did the people in ancient societies preserve the events in the past?
Answer:
The ancient people preserved the events in the past so that they can pass them to the next generation. They used various means to do this:

• Narrating the stories of valour of ancestors to the next generation.
• Stories of their life preserved through cave paintings.
• Adopting story telling technique.
• Singing songs and ballads to impress events upon the minds of the new generation.

Question 14.
Answer the following questions in detail:
(a) Which experts do we need in order to prove the reliability of historical documents?
Answer:
The following experts are required to prove the reliability of historical documents:

• Language expert who can decipher the language and meaning of the document or the script on the inscription.
• One who can recognise the type of paper used and the period in which it was used.
• One who can understand the lettering style and the writing style of the author.
• Expert who has knowledge of different seals, i.e. stamps of authority used by the rulers.
• Historian who can interpret and do a comparative study of the references given in the document.

(b) Write Hegel’s view on history.
Answer:

• Georg Wilhelm Friedrich Hegel was a German philosopher.
• He was of the view that the historical realities should be presented in a logical manner.
• He believed that presentation of history is bound to change as time passes because new evidence surfaces.
• He proposed a method of analysis based on opposites known as ‘Dialectics’.
• Hegel’s philosophy convinced many scholars that historical methods were not of lesser quality, though they differed from scientific methods.
• His lectures and articles are published in a book called ‘Encyclopaedia of Philosophical Sciences’. His book ‘Reason in History’ is well known.

Question 15.
Observe the inscription in the picture and write information it:

Answer:

1. A fragment of the earliest inscription is shown in the above picture. It dates back to 4500 BCE.
2. It is displayed at the Louvre museum in France.
3. The inscriptions have names of Sumerian kings and stories of battles fought by them.
4. It shows a forward marching file of soldiers holding shields and spears. The General is in the front.
   Brain Teaser
   Hints:
   Down:
   • He used the word ‘History’ for the first time
   • He wrote the book ‘Discourse on the Method’
   • Presented Theory of ‘Dialectics’
   • He called his method ‘Archaeology of Knowledge’

Across:

• founder of modern historiography
• Criticised imaginative narration of history. Articles published in ‘The Secret of World History’
• Her writings helped in establishing the fundamentals of feminism
• He wrote ‘Das Kapital’
  

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Std 10 Political Science Chapter 3 Question Answer Political Parties Maharashtra Board

Balbharti Maharashtra State Board Class 10 Political Science Solutions Chapter 3 Political Parties Notes, Textbook Exercise Important Questions and Answers.

Class 10 Political Science Chapter 3 Political Parties Question Answer Maharashtra Board

Political Science Class 10 Chapter 3 Question Answer Maharashtra Board

Question 1.
Choose the correct option from the given options and complete the sentences.
(1) When people come together and participate in electoral process, to acquire political power, such organisations are called ………………………….. .
(a) Government
(b) Society
(c) Political parties
(d) Social organisations
Answer:
(c) Political parties

(2) National Conference is a party in ………………………….. this region.
(a) Odisha
(b) Assam
(c) Bihar
(d) Jammu and Kashmir
Answer:
(d) Jammu and Kashmir

(3) Justice Party- a non-Brahmin movement was transformed into ………………………….. Political Party.
(a) Assam Gan Parishad
(b) Shivsena
(c) Dravid Munnetra Kazhagam
(d) Jammu and Kashmir National Conference
Answer:
(c) Dravid Munnetra Kazhagam

Question 2.
State whether the following statements are true or false. Give reasons for your answer.
(1) Political parties act as a link between government and people.
Answer:
The above statement is True.

• The political parties convey the demands and complaints of the people to the government.
• Information about various government policies and schemes are conveyed to the people by the political parties.
• People’s reaction to the policies and their expectations are conveyed to the government too by the parties. In this way, political parties act as a link between government and the people.

(2) Political parties are social organisations.
Answer:
The above statement is True.

• People who have similar views come together voluntarily and form a party, so it can be said that political parties are an integral part of our society.
• The political parties try to solve the problems of the people.
• Some political parties represent the role of a particular community in society, its ideology and work to achieve it. Hence it can be said that political parties are social organizations.

(3) Coalition politics leads to instability.
Answer:
The above statement is False.

• As no single party got majority after the elections held in 1989, coalition government came to power at the centre and many states.
• Parties had to set aside their policies and programmes and concentrate on a common agenda to run the government.
• Both Congress Party and the Bharatiya Janata Party made an experiment of establishing a coalition government.
• The National Democratic Alliance formed by BJP and its partners and the Democratic Front government formed by Congress and its partners ruled at the centre and state level effectively.

Therefore, the belief that the coalition government brings instability was proved wrong.

(4) Shiromani Akali Dal is a national party.
Answer:
The above statement is False.
The Election Commission of India recognises a political party as National or Regional party on the basis of specific criteria namely:

• The number of seats secured in Parliament and Legislative Assembly or percentage of votes secured.
• Shiromani Akali Dal does not meet the criteria listed above.
• As its influence is limited to the state of Punjab and not in any other state.
• The Election Commission has given recognition to it as regional party.

Question 3.
Explain the following concepts.
(1) Regionalism
Answer:

• India is a vast country with great physical diversity. People belonging to different regions have their own language, culture and traditions.
• Along with the physical diversity, we find diversity in literature, education, history and movements.
• Each one feels an affinity for his language, traditions and history of social reforms. This gives rise to linguistic identity.
• This affinity towards all the above-mentioned aspects develops into identity consciousness and gives rise to excessive regional pride.
• People start giving preference only to the development of their language and region.
• This is known as Regionalism.

(2) National Parties
Answer:
A party which functions at the national level is known as National Party.

1. The Election Commission has laid certain criteria for a party to get recognised as a Political party. The political party should secure at least f 6% valid votes in four or more states in the earlier Lok Sabha. OR
2. State Assembly elections and minimum four members should be elected in the Lok Sabha from any state or states in the earlier elections. OR
3. The candidates of a party should be elected from a minimum three states or should be elected from a minimum 2% constituencies of the total Lok Sabha constituencies. OR
4. It is important to get recognition as a state party in at least four states.

Question 4.
Answer the following questions in brief.
(1) What are the major characteristics of political parties?
Answer:
The main features of political parties are as follows:

• Political parties aim at securing power by contesting elections.
• Every political party has some ideology.
• Every party has an agenda. It is based on the party’s ideology.
• The party that gets majority seats in election forms the government and the one that does not secure the majority act as opposition parties.
• Political parties are a link between the people and the government and work to gain the support of the people.

(2) What changes have taken place in the nature of political parties in India?
Answer:
The following changes were seen in the party system in India:

• Indian- National Congress was the only dominant party in states and at the centre after independence.
• All other parties came together and formed a coalition in 1977 and defeated the Congress.
• For the first time in history, the two-party system got importance over one-party system.
• The one-party system came to an end after the 1989 elections.
• Regional parties got importance and the coalition government was formed at the centre and in the states.

Project
(1) In a map of Maharashtra, point out the Loksabha constituency that includes the names of your parents.
(2) In a map of India, point out the places where national political parties have their influence.
Answer:

Memory Map

Question 5.
Choose the correct option from the given options and complete the sentences:
(a) The party which fails to secure majority is known as ………………………. party.
(a) Ruling
(b) Opposition
(c) Independent
(c) Coalition
Answer:
(b) Opposition

(b) ‘Bharatiya Janata Party’ which was formed in 1980 after a split with ………………………. a component of Janata Party.
(a) Jan Sangh
(b) Lok Dal
(c) Independent party
(b) Janata Dal
Answer:
(a) Jan Sangh.

(c) Social support received by a political party is called ………………………. .
(a) Democracy
(b) People’s rule
(c) Mass base
(d) Public relation
Answer:
(c) Mass base

(d) Promotion of the Marathi language is the objective of the ………………………. .
(a) Dravida Munnetra Kazhagam
(b) Shiromani Akali Dal
(c) Shiv Sena
(d) Assam Gana Parishad
Answer:
(c) Shiv Sena

(e) There are ………………………. recognised parties in India.
(a) five
(b) seven
(c) nine
(d) six
Answer:
(b) seven

(f) The main objective of the political party is to capture ………………………. and retain it.
(a) publicity
(b) victory
(c) power
(d) information
Answer:
(c) power

(g) The ideology of the Communist Party of India is based on ………………………. Philosophy.
(a) Capitalist
(b) Marxist
(c) Democracy
(d) Imperialist
Answer:
(b) Marxist

(h) Shiromani Akali Dal is a prominent regional party in ………………………. state.
(a) Odisha
(b) Assam
(c) Punjab
(d) Jammu and Kashmir
Answer:
(c) Punjab

Question 6.
State whether the following statements are true or false. Give reasons for your answer:

(a) Political parties do not need support of the people.
Answer:
The above statement is False.

• To secure power is the main aim of political parties.
• Political parties have to implement various policies and programmes for the welfare of people and to gain the support of the people.
• The party which solves the issues related to the welfare of the people get support.
• Without the support of the people they can never get a mandate.

Hence, all political parties require support of the people.

(b) The Communist Party of India was split.
Answer:
The above statement is True.

• The Communist Party of- India was established in 1925. The Communist Parties follow Marxist ideology.
• In 1962, due to differences in the leadership a rift was created in the party.
• The main reason for the split was about which political line to follow.

(c) Sometimes the sentiments of regionalism gets strengthened in the country.
Answer:
The above statement is True.

1. A country like India has diversity of government language, region and culture. This diversity creates affinity towards a region.
2. This affinity gives rise to excessive regional S pride and initiating movements to save it. The significance of such movements is claimed to be for preserving culture.
3. Asserting to be rightful claimant of material resources, job opportunities and development of the region these movements strengthen the regional pride.
4. Thus, this excessive regional pride turns morbid taking the form of regionalism.

(d) Regional parties have no influence on National Politics.
Answer:
The above statement is False.

• No single party got majority in the elections to Lok Sabha held in 1989.
• The national parties formed coalition government at the centre taking help of regional parties.
• As regional parties share power at the centre they have influence on national politics.

Question 7.
Explain the concept:
(a) Regional Parties:
Answer:

1. The groups having a proud feeling about the different identity of their region and who compete to capture power to bring about regional development are ‘Regional Parties’.
2. The influence of such parties are limited to their region. They give importance to regional problems. Development of one’s own region is the prime objective of these parties.
3. Sometimes they demand for independent state or autonomy. They influence the national politics because of their dominance in the region.
4. They have passed through various phases, from separatism to autonomy and have then merged with mainstream national politics.

(b) Political Party:
Answer:

1. A Political Party is a kind of social organisation of like-minded people. The main aim of any political party is to contest election and secure power.
2. The stand taken by various political parties on issues becomes their political ideology.
3. In democracy, political parties are at the centre of all political activities. They are a link that connects common people, democracy, representation and elections.
4. The party that secures a majority becomes the ruling party and the rest are known as the. opposition.

Question 8.
Write short note:
(a) Party System:
Answer:

1. If one party remains in power in a country for a long period and no other party has any kind of influence the party system it is called ‘One- Party System’.
2. When there are two equally strong parties which alternatively come to power. It is called ‘Two-Party System’.
3. In a country where many political parties exist and compete with each other to capture power and have more or less influence in different states is called ‘Multi-Party System’.
4. Democracy develops in Multi-Party System.

(b) Indian National Congress:
Answer:

• The Indian National Congress was established in 1885.
• The party represented the hopes and aspirations of Indians and led the freedom struggle.
• Groups having diverse ideologies became part of the Congress to fight for freedom.
• It believes in democratic socialism, social equality and international peace.
• After independence, the Congress Party was a dominant party for almost four decades and ruled at the centre and in the states.

(c) Communist Party of India:
Answer:

• The Communist Party of India was established in 1925. The Communist Party follows the Marxist ideology.
• The party aims at working to protect the interests of workers and labourers.
• The main objective of this party is to oppose capitalism and protect the interests of workers.
• The party split due to ideological differences in 1964. Those who walked out of the party formed Communist Party (Marxist).

(d) Nationalist Congress Party:
Answer:

• Nationalist Congress Party (NCP) is the splinter or breakaway party from the Congress Party.
• It considers the values like democracy, equality and secularism important.
• It became part of United Progressive Alliance (UPA) and came to power in Maharashtra.
• It was in power in Maharashtra from 1999 to 2014 and at the centre from 2004 to 2014.

(e) Trinamool Congress:
Answer:

• All India Trinamool Congress was established in 1998.
• The Election Commission of India gave it recognition in 2016.
• Democracy, Secularism and protection of the weaker sections of the society are some of the policies of the party.
• Presently (April 2019), this party is in power in the state of West Bengal.

(f) Shiv Sena:
Answer:

1. The Shiv Sena was founded in 1966.
2. The main objective of the party was to fight for the cause of Marathi-speaking people and preservation of Marathi language.
3. They resisted the people from other regions.
4. In 1995, it became the ruling party with BJP in Maharashtra and its strategic tie-up with BJP helped it to enter national politics.
5. It was in power at the centre with BJP from 1998 to 2004. Again it has shared power with the BJP at the centre and state since 2014.

(g) Shiromani Akali Dal:
Answer:

• Shiromani Akali Dal was formed in 1920.
• It is a dominating party in Punjab.
• It gives preference to nurture religious and for the regional pride.
• The party has retained power in Punjab for many years.

(h) Dravid Munnetra Kazhagam:
Answer:

• Justice party, a non-Brahmin movement, started in 1920. In 1944, it transformed into a political party called Dravid Kazhagam.
• In 1949, a group within the party got split and formed Dravid Munnetra Kazhagam (DMK).
• The party works for the protection of Tamil identity.
• This party implemented many policies for welfare of the people and therefore has support from all the sections of society.
• Another group separated from it in 1972 and formed All India Dravid Munnetra Kazhagham.
• It remained in power for a long time in Tamil Nadu and for sometime at the centre.

Question 9.
Do as directed
(a) Complete the concept map:

Answer:

Answer:

(3)

Answer:

(b) Complete the Time-line writing the name of the party or the year of establishment:

Answer:

Question 10.
Answer the following questions in brief:

(a) What is called “mass base”?
Answer:

• Every political party is formed with some ideology.
• Political parties take a certain stand towards public issues.
• Their ideology and their stand towards public issues are conveyed to the people through various programmes.
• If the people agree with their role and ideology, they get the support of the people.
• Such social support received by a political – party is called ‘mass base’.

(b) Write about the policies of Indian National Congress.
Answer:
The policies of the Indian National: Congress are as follows:

• Equal rights for the minorities and weaker sections of society.
• Secularism, all-round development and social welfare are its objectives.
• Introduction of socialist democracy.
• Belief in values like international peace and social equality.

(c) Explain the role of Bharatiya Janata Party.
Answer:
Bharatiya Janata Party was formed in 1980 with the following objectives:

• To preserve Indian culture and traditions.
• To create a strong and rich India.
• To give importance to economic reforms for development of India.

(d) Write about the policies of Communist Party of India (Marxist).
Answer:
Communist Party of India (Marxist) was formed in 1964 with the following objectives:

• The party advocates socialism, secularism and democracy.
• The main policy of the party is to work for the welfare of farmers, landless labourers and workers.
• The party opposes imperialism.

(e) Why was Bahujan Samaj Party formed?
Answer:
The Bahujan Samaj Party was formed in 1984 to achieve the following objectives:

• To bring socialist ideology into practice.
• To secure power for ‘majority’ comprising of scheduled castes, scheduled tribes and other backward classes.
• To give power in the hands of ‘majority’.

(f) What do the regional parties give preference for?
Answer:
The regional parties give preference to the following issues:

• Importance should be given to regional issues and bring about development.
• Regional issues should be handled* at regional level.
• The power rests in the hands of regional people. ‘
• People living in that region should get preference in administration and jobs. .

(g) What changes are seen in the nature and role of regional parties?
Answer:
The role of regional parties changed over period of time. The changes are as follows:

• After independence, regional identity gave rise to separatists movements and demands were put up by regional parties for separate state.
• They wanted to break away from the Indian union and form a separate state.
• The demands of the regional parties changed gradually and these parties started asking for autonomy.
• In the later period, for the development of their region and people the parties demanded representation of their people in the state and central government.
• Regional parties in the north eastern region also started demanding more autonomy after split up.
• The journey of the regional parties began with a split up and then a demand for autonomy going on to share power in federation and then entry into mainstream national politics.

(h) What are the objectives of Assam Gana Parishad?
Answer:
Assam Gana Parishad was formed in 1985 with the following objectives:

• To preserve the uniqueness of Assam’s culture, language and social identity.
• To make efforts for economical development of Assam.
• To resolve problems of displaced people.

(i) What are the criteria for a regional party to get recognition?
Answer:

• In the last general .elections to the State Assembly, the party should not secure less than 6% of the total number of valid votes polled.
• At least 2 members to be elected to the Legislative Assembly (Vidhan Sabha).
• 3% seats of the total seats of Legislative Assembly or at least 3 seats in Legislative Assembly.

(j) What work is done by political parties?
Answer:
The following work is done by political parties:

• To propagate policies and programmes of the party and contest elections.
• They implement various policies when they come to power.
• If they fail to secure power, they act as opposition party and try to gain support of the people.
• They communicate the demands and complaints of the people to the government and the policies and programmes of the government to the people.

Question 11.
Give your opinion:

(a) Imagine you are opposition party leader and you have observed that the ruling party has not done good work in the field of health. What will you do as a leader of opposition?
Answer:
As opposition leader, I will do the following to make the government realise its negligence in the health field:

• I will question the government in Parliament and point out their shortcomings and ask about the prolonged projects.
• I will create awareness among the people by writing articles in newspapers.
• I will give interviews,on radio and television and criticize the government.
• I will organise rallies and meetings to sensitize among the people.

(b) Think and write
What has to be done to bring partyless democracy in modern times?
Answer:

• The recognition of all the parties should be cancelled. ‘
• People should be given the right to make decisions.
• In order to improve the decision-making power, people should be educated on political issues.
• To improve the moral character of the people who want to take the leadership.
• To initiate direct democracy and prepare the people for the same.
• Stress should be given for decentralization.
• Mahatma Gandhi, Vinoba Bhave and Jayprakash Narayan put forth the idea of partyless democracy.
• What has to be done to bring such democracy in modern times?

Question 12.
What do you understand by the following news in newspapers? Explain in brief.

(a) Opposition parties held a meeting in Mumbai to resist the Ruling party. Will take up the issue of farmers?
Answer:

• The ruling party did not undertake any work for the welfare of farmers. Therefore all the opposition parties decided to trap the government on this issue.
• The opposition parties have kept aside their differences and come together for this cause.
• It is the duty of the opposition party to question the negligence of the government.
• This news makes us aware of the line of action taken by the opposition.
• Opposition parties held a meeting in Mumbai to resist the Ruling party. Will take up the issue of farmers?
• Ruling party organised ‘Samvad Yatra’ in rural areas.

(b) Ruling party has organised ‘Samvad Yatra’ in rural areas.
Answer:

• Political parties adopt different ways to popularise their party and influence the people.
• As the means of communication are limited in rural areas they organise the Yatra.
• It shows the efforts of the government to understand problems of people in rural areas.
• It is essential to have dialogue with people to know their problems and opinions.
• As the initiative is taken by the government, people will develop faith in government.
• The news conveys to us that the ruling party is carrying out its duties properly.
• The faith in government becomes profound when people feel that government is sensitive towards them.

Class 10 Political Science Textbook Solutions Answers

• Working of the Constitution Class 10 Political Science Textbook Solutions
• The Electoral Process Class 10 Political Science Textbook Solutions
• Political Parties Class 10 Political Science Textbook Solutions
• Social and Political Movements Class 10 Political Science Textbook Solutions
• Challenges faced by Indian Democracy Class 10 Political Science Textbook Solutions

Algebraic Formulae – Expansion of Squares Class 7 Maths Chapter 14 Practice Set 50 Solutions Maharashtra Board

Balbharti Maharashtra State Board Class 7 Maths Solutions covers the 7th Std Maths Practice Set 50 Answers Solutions Chapter 14 Algebraic Formulae – Expansion of Squares.

Std 7 Maths Practice Set 50 Solutions Answers

Question 1.
Expand:
i. (5a + 6b)²
ii. \(\left(\frac{\mathrm{a}}{2}+\frac{\mathrm{b}}{3}\right)^{2}\)
iii. (2p – 3q)²
iv. \(\left(x-\frac{2}{x}\right)^{2}\)
v. (ax + by)²
vi. (7m – 4)²
vii. \(\left(x+\frac{1}{2}\right)^{2}\)
viii. \(\left(a-\frac{1}{a}\right)^{2}\)
Solution:
i. (5a + 6b)²
Here, A = 5a and B = 6b
(5a + 6b)² = (5a)² + 2 × 5a × 6b + (6b)²
…. [(A + B)² = A² + 2AB + B²]
∴ (5a + 6b)² = 25a² + 60ab + 36b²

ii. \(\left(\frac{\mathrm{a}}{2}+\frac{\mathrm{b}}{3}\right)^{2}\)
Here A = \(\frac { a }{ 2 }\) and B = \(\frac { b }{ 3 }\)

iii. (2p – 3q)²
Here, a = 2p and b = 3q
(2p – 3q)² = (2p)² – 2 × (2p) × (3q) + (3q)²
…. [(a – b)² = a² – 2ab + b²]
∴ (2p – 3q)² = 4p² – 12pq + 9q²

iv. \(\left(x-\frac{2}{x}\right)^{2}\)
Here a = x and b = \(\frac { 2 }{ x }\)

v. (ax + by)²
Here, A = ax and B = by
(ax + by)² = (ax)² + 2 × ax × by + (by)²
…. [(A + B)² = A² + 2AB + B²]
∴ (ax + by)² = a²x² + 2abxy + b²y²

vi. (7m – 4)²
Here, a = 7m and b = 4
(7m – 4)² = (7m)² – 2 × 7m × 4 + 4²
…. [(a – b)² = a² – 2ab + b²]
∴ (7m – 4)² = 49m² – 56m + 16

vii. \(\left(x+\frac{1}{2}\right)^{2}\)
Here a = x and b = \(\frac { 1 }{ 2 }\)

viii. \(\left(a-\frac{1}{a}\right)^{2}\)
Here A = a and B = \(\frac { 1 }{ a }\)

Question 2.
Which of the options given below is the square of the binomial
(A) \(64-\frac{1}{x^{2}}\)
(B) \(64+\frac{1}{x^{2}}\)
(C) \(64-\frac{16}{x}+\frac{1}{x^{2}}\)
(D) \(64+\frac{16}{x}+\frac{1}{x^{2}}\)
Solution:
(C) \(64-\frac{16}{x}+\frac{1}{x^{2}}\)

Hint:
= \(\left(8-\frac{1}{x}\right)^{2}=8^{2}-2 \times 8 \times \frac{1}{x}+\left(\frac{1}{x}\right)^{2}\) …[(a – b)² = a² – 2ab + b²]
= \(64-\frac{16}{x}+\frac{1}{x^{2}}\)

Question 3.
Of which of the binomials given below is the m²n² + 14mnpq + 49p²q² the expansion?
(A) (m + n) (p + q)
(B) (mn – pq)
(C) (7mn + pq)
(D) (mn + 7pq)
Solution:
(D) (mn + 7pq)

Hint:
Here, square root of the first term = mn
Square root of the last term = 7pq
∴ Required binomial = (mn + 7pq)²

Question 4.
Use an expansion formula to find the values of:
i. (997)²
ii. (102)²
iii. (97)²
iv. (1005)²
Solution:
i. (997)² = (1000 – 3)²
Here, a = 1000 and b = 3
(1000 – 3)² = (1000)² – 2 x 1000 x 3 + 3²
…. [(a – b)² = a² – 2ab + b²]
= 1000000 – 6000 + 9
= 994009
∴ (997)² = 994009

ii. (102)² = (100 + 2)²
Here, a = 100 and b = 2
(100 + 2)² = (100)² + 2 x 100 x 2 + 2²
…. [(a + b)² = a² + 2ab + b²]
= 10000 + 400 + 4
= 10404
∴ (102)² = 10404

iii. (97)² = (100 – 3)²
Here, a = 100 and b = 3
(100 – 3)² = (100)² – 2 x 100 x 3 + 3²
…. [(a – b)² = a² – 2ab + b²]
= 10000 – 600 + 9
= 9409
∴ (97)² = 9409

iv. (1005)² = (1000 + 5)²
Here, a = 1000 and b = 5 (1000 + 5)²
= (1000)² + 2 x 1000 x 5 + 5²
…. [(a + b)² = a² + 2ab + b²]
= 1000000+ 10000 + 25
= 1010025
∴ (1005)² = 1010025

Maharashtra Board Class 7 Maths Chapter 14 Algebraic Formulae – Expansion of Squares Practice Set 50 Intext Questions and Activities

Question 1.
Use the given values to verify the formulae for squares of binomials. (Textbook pg. no. 92)
i. a = -7, b = 8
ii. a = 11,b = 3
iii. a = 2.5,b = 1.2
Solution:
i. (a + b)² = (-7 + 8)²
= 1²
= 1
a² + 2ab + b² = (-7)² + 2 x (-7) x 8 + 8²
= 49 – 112 + 64
= 1
∴(a + b)² = a² + 2ab + b²
(a – b)² = (-7 – 8)²
= (-15)²
= 225
a² – 2ab + b² = (-7)² – 2 x (-7) x 8 + (8)²
= 49 + 112 + 64
= 225
∴(a – b)² = a² – 2ab + b²

ii. (a + b)² = (11 + 3)²
= 14²
= 196
a² + 2ab + b² = 11² + 2 x 11 x 3 + 3²
= 121 + 66 + 9
= 196
∴(a + b)² = a² + 2ab + b²
(a – b)² = (11 – 3)² = 8²
= 64
a² – 2ab + b² = 11² – 2 x 11 x 3 + 3²
= 121 – 66 + 9
= 64
∴(a – b)² = a² – 2ab + b²

iii. (a + b)² = (2.5 + 1.2)²
= 3.7²
= 13.69
a² + 2ab + b² = (2.5)² + 2 x 2.5 x 1.2 + (1.2)²
= 6.25 + 6 + 1.44
= 13.69
∴(a + b)² = a² + 2ab + b²
(a – b)² = (2.5 – 1.2)²
= 1.32
= 1.69
a² – 2ab + b² = (2.5)² – 2 x 2.5 x 1.2 + (1.2)²
= 6.25 – 6 + 1.44
= 1.69
∴(a – b)² = a² – 2ab + b²-

Class 7 Maths Solution Maharashtra Board

• Pythagoras’ Theorem Practice Set 48 Class 7 Maths Solution
• Pythagoras’ Theorem Practice Set 49 Class 7 Maths Solution
• Algebraic Formulae – Expansion of Squares Practice Set 50 Class 7 Maths Solution
• Algebraic Formulae – Expansion of Squares Practice Set 51 Class 7 Maths Solution
• Algebraic Formulae – Expansion of Squares Practice Set 52 Class 7 Maths Solution
• Algebraic Formulae – Expansion of Squares Practice Set 53 Class 7 Maths Solution
• Statistics Practice Set 54 Class 7 Maths Solution
• Statistics Practice Set 55 Class 7 Maths Solution

Std 9 Science Chapter 16 Heredity and Variation Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 16 Heredity and Variation Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 16 Heredity and Variation Question Answer Maharashtra Board

Class 9 Science Chapter 16 Heredity and Variation Textbook Questions and Answers

1. Complete the following sentences by choosing the appropriate words from the brackets.
(Inheritance, sexual reproduction, asexual reproduction, chromosomes, DNA, RNA, gene)

a. Hereditary characters are transferred from parents to offsprings by …………………………….., hence they are said to be structural and functional units of heredity.
b. Organisms produced by …………………………….. show minor variations.
c. The component which is in the nuclei of cells and carries the hereditary characteristics is called ……………………………..
d. Chromosomes are mainly made up of ……………………………..
e. Organisms produced through …………………………….. show major variations.

2. Explain the following.

a. Explain Mendel’s monohybrid progeny with the help of any one cross.
Answer:

• Mendel brought about a cross between two pea plants with only pair of contrasting characters. This type of cross is called a monohybrid cross.
• Tall pea plants and dwarf pea plants were used in this cross. Hence this is parent generation (P₁).
  
• All the plants produced in F₁ genration are tall, having genotype Tt. This indicates that the gene responsible for tallness in pea plants is dominant over the gene responsible for dwarfness.
• When F₁ plants are self pollinated they produce second filial generation (F₂).
• In F₂ generation both tall and dwarf plants appeared in the ratio 3:1.
• Thus, the genotypic ratio of F₂ generation is 3 (Tall) : 1 (Dwarf) and the genotypic ratio is 1 TT : 2 Tt: 1 tt.

b. Explain Mendel’s dihybrid ratio with the help of any one cross.
Answer:

• In dihybrid cross, Mendel considered two pairs of contrasting characters.
• He made a cross between a pea plant producing rounded and yellow couloured seeds and a pea plant with wrinkled and green coloured seeds.
  
• All the plants produced in F₁ generation had rounded yellow seeds. This is because in pea plants, round shape of seed is dominant over wrinkled shape and yellow colour of seed is dominant over green colour.
• When F₁ plants are self pollinated, they produce four types of gamates – RY, Ry, rY, ry.
• F₂ plants formed by the fusion of four types of male gametes and four types of female gametes, had phenotypes such as round yellow, wrinkled yellow, round green and wrinkled green.
• Also, F₂ generation showed nine different types of genotypes such as RRYY, RRYy, RRyy, RrYY, RrYy, Rryy, rrYY, rrYy, rryy.
• Phenotypic ratio of dihybrid cross is
  
• The genotypic ratio of dihybrid cross is
  

c. Distinguish between monohybrid and dihybrid cross.
Answer:

d. Is it right to avoid living with a person suffering from a genetic disorder?
Answer:

• No, it is not right to avoid living with a person suffering from a genetic disorder.
• Genetic disorders are transmitted from parents to offsprings only and they are non-contagious, i.e., they do not spread from one person to another through contact.

3. Answers the following questions in your own words.

a. What is meant by ‘chromosome’. Explain its types.
Answer:

• The structure in the nucleus of cells that carries the hereditary characteristics is called the chromosome.
• It is made up mainly of nucleic acids and proteins.
• Depending upon the position of the centromere, there are four types of chromosomes.
  

(a) Metacentric: The centromere is exactly at the mid-point in this chromosome, and therefore, it looks like the English letter ‘V’. The arms of this chromosome are equal in length.

(b) Sub-metacentric: The centromere is somewhere near the mid-point in this chromosome which, therefore, looks like the English letter ‘U. One arm is slightly shorter than the other.

(c) Acrocentric: The centromere is near one end of this chromosome which therefore looks like the English letter One arm is much smaller than the other.

(d) Telocentric: The centromere is right at the end of this chromosome making the chromosome look like the English letter ‘i’. This chromosome consists of only one arm.

b. Describe the structure of the DNA molecule.
Answer:

• In 1953, Watson and Crick proposed a model of the DNA molecule.
• As per their model, two parallel threads (strands) of nucleotides are coiled around each other to form a double helix structure. This structure can be compared with a coiled and a flexible ladder.
• Each strand of DNA is made up of many small molecules known as nucleotides.
• Each nucleotide is made up of a molecule of nitrogen base and phosphoric acid joined to a molecule of sugar.
• There are four types of nitrogen bases-adenine, guanine, cytosine and thymine. Adenine and guanine are called as purines while cytosine and thymine are called as pyrimidines.
• Nucleotides are arranged like a chain in the DNA.
• The two threads (strands) of the DNA are comparable to the two rails of the ladder and each rail is made up of alternately joined molecules of sugar and phosphoric acid.
• Each rung of the ladder is a pair of nitrogenous bases joined by hydrogen bonds. Adenine always pairs with thymine and cytosine always pairs with guanine.

c. Express your opinion about the use of DNA fingerprinting.
Answer:

• DNA fingerprinting is the technique in which the sequence of the genes in the DNA of a person, i.e., the genome of the person is identified.
• This technique is useful to identify the lineage and to identify criminals because it is unique to every person.
• It is also useful to identify paternity and maternity disputes etc.
• This technique was developed by Professor of genetics Sir Alec Jeffreys.
• A common method of collecting a reference sample, is in the use of a buccal swab. If this is not available, blood or saliva or hair sample may be used.
• Just like your actual fingerprint, your DNA fingerprint is something that you are born with. It is unique to you.
• DNA fingerprint is very useful in forensic science.

d. Explain the structure, function and types of RNA.
Answer:

• Ribonucleic acid (RNA) is an important nucleic acid of the cell.
• RNA is made up of ribose sugar, phosphate molecules and four types of nitrogenous bases adenine, guanine, cytosine and uracil.
• The nucleotide i.e., smallest unit of the chain of the RNA molecule is formed by the combination of a ribose sugar, phosphate molecule and one of the nitrogen bases.
• Large numbers of nucleotides are bonded together to form the macromolecule of RNA.
• RNA performs the function of protein synthesis.
• According to function, there are three types of RNA:
  (a) Ribosomal RNA (rRNA): It is the component of cellular organelle ribosome. Ribosomes perform the function of protein synthesis.(b) Messenger RNA (mRNA): It carries the information for protein synthesis from genes (i.e. DNA segment in the cell nucleus) to ribosomes (in the cytoplasm) which produce the proteins.(c) Transfer RNA (tRNA): It carries the amino acid up to the ribosomes as per the message of the mRNA.

e. Why is it necessary for people to have their blood examined before marriage?
Answer:

• If people have their blood examined before marriage, the partners will know about the possible genetic diseases that their children might inherit. So they may decide not to have children or not to get married.
• Blood tests before marriage are also done to check for any contagious disease in the partners. This will help to protect the partners from contagious diseases like STDs.

4. Write a brief note on each.

a. Down syndrome
Answer:

• Down syndrome is the disorder arising due to chromosomal abnormality.
• This is the first discovered and described the chromosomal disorder in human beings.
• This disorder is characterized by the presence of 47 chromosomes. It is described as the trisomy of the 21st pair.
• Infants with this disorder have one extra chromosome with the 21st pair in every cell of the body. Therefore, they have 47 chromosomes instead of 46.
• Children suffering from Down syndrome are usually mentally retarded and have a short lifespan. Mental retardation is the most prominent characteristic.
• Other symptoms include short height, short wide neck, flat nose, short fingers, scanty hair, single horizontal crease on palm and a life expectancy of about 16-20 years.

b. Monogenic disorders
Answer:

• Disorders occurring due to mutation in any single gene into a defective one are called monogenic disorders.
• Approximately 4000 disorders of this type are now known.
• Due to abnormal genes, their products are either produced in insufficient quantity or not produced at all.
• It causes abnormal metabolism and may lead to death at a tender age.
• Examples of monogenic disorders are Hutchinson’s disease, Tay-Sachs disease, galactosaemia, phenylketonuria, sickle cell anaemia, cyctic fibrosis, albinism, haemophilia, night blindness etc.

c. Sickle cell anaemia: symptoms and treatment.
Answer:

• Sickle-cell anaemia is a hereditary disease caused due to mutation in a single gene. It is a monogenic disorder.
• Normal haemoglobin has glutamic acid as the 6th amino acid in its molecular structure. However, if it is replaced by valine, the shape/structure of the haemoglobin molecule, changes.
• Due to this, the erythrocytes (RBCs) which are normally biconcave become sickle-shaped. This condition is called sickle-cell anaemia. The oxygen-carrying capacity of haemoglobin in such individuals is very low.
• In this condition, clumping and thereby, destruction of erythrocytes occurs most often. As a result, blood vessels are obstructed and the circulatory system, brain, lungs, kidneys, etc. are damaged.
• Symptoms of sickle-cell anaemia are swelling of legs and hands, pain in joints, severe general body aches, frequent cold and cough, constant low-grade fever, exhaustion, pale face, low haemoglobin count.
• A person suffering from sickle-cell anaemia should take a tablet of folic acid daily.

5. How are the items in groups A, B and C inter-releated?

6. Filling the blanks based on the given relationship.
a. 44 + X : Turner syndrome : : 44 + XXY: – ……………………………..
b. 3:1 Monohybrid : : 9:3:3:1 : ……………………………..
c. Women : Turner syndrome : : Men : ……………………………..
Answer:
a. Klinefelter syndrome
b. Dihybrid
c. Klinefelter syndrome

7. Complete the tree diagram below based on types of hereditary disorders.

Answer:

Class 9 Science Chapter 12 Study of Sound Intext Questions and Answers

Question 1.
How do specific traits or characteristics appear in organisms? (Can you tell; Textbook Page No. 180)
Answer:

• Information necessary for synthesis of a particular protein is stored in the DNA.
• The segment of DNA which contains all the information for synthesis of a particular protein is called a gene for that protein.
• To understand how a specific trait is expressed, let us consider plant height as an example.
• We know that there are growth hormones in plants. Increase in the height of plants depends upon the quantity of growth hormones.
• The quantity of growth hormone produced by a plant depends upon the efficiency of the concerned enzyme.
• Efficient enzymes produce a greater quantity of the hormone due to which the height of the plant increases.
• However, if the enzymes are less efficient, a smaller quantity of hormone is produced leading to the stunting of the plant.
• Thus, the expression of traits is controlled by the genes.

Question 2.
Show the monohybrid cross between (RR) and (rr) and write the phenotypic and genotypic ratio of F₂ generation. (Use your brain power; Textbook Page No. 187)
Answer:
Parental Generation (P₁)

Phenotypic ratio : 3 Round : 1 Wrinkled
Genotypic ratio : 1 RR : 2 Rr : 1 rr

Question 3.
Why did the characteristic of the Rounded- Yellow seeds alone appear in the Fj generation but not the characteristic of the wrinkled- green seeds? (Use your brain power; Textbook Page No. 187)
Answer:

• Rounded-Yellow seeds is a dominant characteristic whereas wrinkled-green seeds is a recessive characteristic.
• Therefore only the characteristic of Rounded- Yellow seeds appeared in the F1 generation.

Question 4.
Do all boys and girls of your class look alike? (Think about it; Textbook Page No. 179)
Answer:

• No, all the boys and girls of my class do not look alike.
• There is a lot of variation among them.

Question 5.
Carefully observe your classmate’s earlobes. (Observe; Textbook Page No. 179)
Answer:

• Most of the classmates have free earlobes while very few have attached ear lobes.
• This shows that in humans free earlobes is a dominant characteristic whereas attached earlobe is a recessive characteristic.

Question 6.
Irrespective of all of us being humans, what difference do you notice in our skin colour? (Observe; Textbook Page No. 179)
Answer:

• Irrespective of all of us being humans, there is a lot of variation in our skin colour. Some people are light-skinned while some are dark-skinned.
• The difference in skin colour is due to the gene responsible for the production of the pigment melanin.

Question 7.
All of you are in std. IX. Why then are some students tall and some short? (Observe; Textbook Page No. 179)
Answer:
Our height is decided by gene. People who are tall have genes for tallness whereas people who are short have genes for shortness and hence the variation.

Class 9 Science Chapter 12 Study of Sound Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
The similarities and differences are all the effect of
(a) Heredity
(b) Fertilization
(c) Evolution
(d) Natural selection
Answer:
(a) Heredity

Question 2.
Each chromosome appears midway during cell division.
(a) Circular
(b) Rod-shaped
(c) Dumbbell-shaped
(d) Bottle-shaped
Answer:
(c) dumbbell-shaped

Question 3.
The chromosome in which the centromere is exactly at the mid-point is called chromosome.
(a) sub-metacentric
(b) metacentric
(c) acrocentric
(d) telocentric
Answer:
(b) metacentric

Question 4.
The chromosome in which the centromere is somewhere near the mid-point is called chromosome.
(a) metacentric
(b) acrocentric
(c) sub-metacentric
(d) telocentric
Answer:
(c) sub-metacentric

Question 5.
The chromosome in which the centromere is near one end of the chromosome is called chromosome.
(a) metacentric
(b) acrocentric
(c) sub-metacentric
(d) telocentric
Answer:
(d) telocentric

Question 6.
Sex chromosomes are called
(a) homologous chromosomes
(b) autosomes
(c) allosomes
(d) metacentric chromosomes
Answer:
(c) allosomes

Question 7.
Which of the following is absent in RNA?
(a) Adenine
(b) Uracil
(c) Cytosine
(d) Thymine
Answer:
(d) Thymine

Question 8.
DNA was discovered by
(a) Watson and Crick
(b) Frederick Miescher
(c) Gregor Johann Mendel
(d) Robert Brown
Answer:
(b) Frederick Miescher

Question 9.
The double helix model of DNA was produced by
(a) Watson and Crick
(b) Frederick Miescher
(c) Gregor Johann Mendel
(d) Robert Hooke
Answer:
(a) Watson and Crick

Question 10.
The molecule of RNA which is a component of the ribosome organelle is called a
(a) mRNA
(b) tRNA
(c) rRNA
(d) DNA
Answer:
(c) rRNA

Question 11.
In a monohybrid cross, the phenotypic ratio of F, generation is
(a) 1 tall: 3 dwarf
(b) 2 tall: 2 dwarf
(c) 3 tall: 1 dwarf
(d) 3 tall: 2 dwarf
Answer:
(c) 3 talhl dwarf

Question 12.
arises due to either inheritance of only X chromosome from parents or due to inactivation of the gender-related part of X-chromosomes.
(a) Down syndrome
(b) Turner syndrome
(c) Klinefelter syndrome
(d) Albinism
Answer:
(b) Turner syndrome

Question 13.
Progenies of normal man and sufferer woman for sickle-cell anaemia will be
(a) all normal
(b) 25% normal and 75% sufferer
(c) all carrier
(d) all sufferer
Answer:
(c) all carrier

Question 14.
is a mitochondrial disorder.
(a) Down syndrome
(b) Cleft palate
(c) Spina bifida
(d) Leber hereditary optic neuropathy
Answer:
(d) Leber hereditary optic neuropathy

Question 15.
is a monogenic disorder.
(a) Haemophilia
(b) Cleft palate
(c) Diabetes
(d) Spina bifida
Answer:
(a) Haemophilia

Question 16.
is a recessive character of pea plant.
(a) Round shape of seeds
(b) White colour of flowers
(c) Green colour of pods
(d) Inflated shape of pods
Answer:
(b) White colour of flowers

Question 17.
is a dominant character of pea plant.
(a) Dwarf height
(b) Yellow colour of pod
(c) Yellow colour of seeds
(d) Terminal position of flower
Answer:
(c) Yellow colour of seeds

Question 18.
is a dominant character in human beings.
(a) Non-rolling tongue
(b) Attached ear lobe
(c) Absence of hair on arms
(d) Free ear lobe
Answer:
(d) Free ear lobe

Question 19.
is a recessive character in human beings.
(a) Absence of hair on arms
(b) Black and curly hair
(c) Free earlobe
(d) Presence of hair on arms
Answer:
(a) Absence of hair on arms

Question 20.
If one parent is normal and one parent is carrier of sickle-cell anaemia, then the progenies will be
(a) all normal
(b) 50% normal and 50% carrier
(c) 50% carrier and 50% sufferer
(d) all carrier
Answer:
(b) 50% normal and 50% carrier

Question 21.
If one parent is carrier and one parent is a sufferer of sickle-cell anaemia, then the progenies will be
(a) 50% normal and 50% carrier
(b) all sufferers
(c) 50% carrier and 50% sufferer
(d) all carrier
Answer:
(c) 50% carrier and 50% sufferer

Find the odd man out:

Question 1.
Adenine, thymine, cytosine, uracil
Answer:
Adenine. It is a purine whereas the others are pyrimidines.

Question 2.
Axillary flower, green pod, green seed, inflated pod
Answer:
Green seed. It is a recessive character of pea plant whereas the others are dominant characters.

Question 3.
Constricted pod, purple flower, axillary flower, yellow seeds.
Answer:
Constricted pod. It is a recessive character of pea plant whereas the others are dominant characters.

Question 4.
Green seeds, wrinkled seeds, terminal flower, green pod.
Answer:
Green pod. It is a dominant character of pea plant whereas the others are recessive characters.

Question 5.
Attached ear lobes, brown and straight hair, non-rolling tongue, presence of hair on arms.
Answer:
Presence of hair on arms. It is a dominant characteristic of human beings whereas the others are recessive characters.

Question 6.
Cystic fibrosis, albinism, spina bifida, sicklecell anaemia.
Answer:
Spina bifida. It is a polygenic disorder whereas the others are monogenic disorders.

Question 7.
Fiutchinson’s disease, phenylketonuria, nightblindness, leber hereditary optic neuropathy.
Answer:
Leber hereditary optic neuropathy. It is a mitochondrial disorder whereas the others are monogenic disorders.

Complete the analogy:

a. Tall plant: Phenotype :: Tt:
b. Dominant trait : Axial position of flower :: Recessive trait:
c. Women : 44 + XX :: Men :
d. Adenine and Guanine : Purine :: Cytosine and Thymine :
Answer:
a. Genotype
b. Terminal position of flower
c. 44 + XY
d. Pyrimidine

Match the columns

Question 1.

Answer:
(1 – c – iv),
(2 – d – v),
(3 – e – i),
(4-b- Hi),
(5 – a – ii)

Question 2.

Answer:
(1 – c),
(2 – d),
(3 – b),
(4 – a)

Question 3.

Answer:
(1 – d),
(2 – a),
(3 – b),
(4 – c)

State whether the following statements are true or false. Correct the false statement:

Question 1.
Offsprings produced through asexual reproduction show greater variations as compared to those produced through sexual reproduction.
Answer:
False. Offsprings produced through asexual reproduction show minor variations as compared to those produced through sexual reproduction.

Question 2.
Information necessary for protein synthesis is stored in the RNA.
Answer:
False. Information necessary for protein synthesis is stored in the DNA.

Question 3.
The quantity of growth hormone produced by a plant depends upon the efficiency of the concerned enzyme.
Answer:
True

Question 4.
The chromosome in which the centromere is exactly at the mid-point is called telocentric chromosome.
Answer:
False. The chromosome in which the centromere is exactly at the mid-point is called metacentric chromosome.

Question 5.
RNA molecules are called master molecules.
Answer:
False. DNA molecules are called master molecules.

Question 6.
The pair of sex chromosomes are called autosomes.
Answer:
False. The pair of sex chromosomes is called allosomes.

Question 7.
In DNA, Adenine always pairs with thymine and cytosine always pairs with guanine.
Answer:
True

Question 8.
In humans there are 23 pairs of autosomes and one pair of allosomes.
Answer:
False. In humans, there are 22 pairs of autosomes and one pair of allosomes.

Question 9.
The phenotypic and genotypic ratios are not same.
Answer:
True

Question 10.
Phenotype means the pairs of genes responsible for the visible characteristics of organisms.
Answer:
False. Phentotype means external appearance of visible characteristics of organisms.

Question 11.
During gamete formation, in Pj generation the pair of gametes separate independently.
Answer:
True

Question 12.
Down syndrome is caused due to monosomy of X chromosome.
Answer:
False. Down syndrome is caused due to trisomy of 21st chromosome.

Question 13.
In Klinefelter syndrome, women are sterile.
Answer:
False. In Klinefelter syndrome, men are sterile as this disorder arises in men due to abnormality in sex chromosome.

Question 14.
If the father and mother are both sufferers or carriers of sickle-cell anaemia, their offsprings are likely to suffer from this disease.
Answer:
True

Question 15.
During fertilization, mitochondria is contributed by the sperm cell and egg cell(ovum).
Answer:
False. During fertilization, mitochondria is contributed by the egg cell (ovum) alone.

Question 16.
Polygenic disorders strictly follow Mendel’s principles of heredity.
Answer:
False. Polygenic disorders do not strictly follow Mendel’s principles of heredity.

Question 17.
Genetic material is transferred in equal quantity from parents to progeny.
Answer:
True

Give scientific reasons:

Question 1.
DNA molecules are called as ‘Master molecules’.
Answer:

• Molecules of DNA are present in all organisms from viruses and bacteria to human beings.
• These molecules control the functioning, growth and division (reproduction) of the cell.
• Genes present in the DNA are also responsible for transfer of hereditary characteristics from parents to offsprings.
• Therefore, DNA molecules are called as ‘Master molecules’.

Question 2.
Phenotypic and genotypic ratios are different.
Answer:

• Phenotype means external appearance or visible characteristics of organisms whereas the genotype is the pairs of genes responsible for the visible characteristics.
• The genes responsible for any particular character are present in pairs.
• Though, there are two genes, the phenotype
  depends on the presence of the dominant gene, e.g. Genotype for tall height of the plant is TT or Tt.
• Therefore, phenotypic and genotypic ratios are different.

Question 3.
A carrier or sufferer of sickle-cell anaemia should avoid marriage with another carrier or sufferer.
Answer:

• Sickle-cell anaemia is a hereditary disease caused due to mutation of a single gene.
• It is a monogenic disorder that occurs due to changes in a gene during conception.
• If father and mother both are sufferers or carriers of sickle-cell anaemia, their offsprings are likely to suffer from the disease.
• Therefore, a carrier or sufferer of sickle-cell anaemia should avoid marriage with another carrier or sufferer.

Question 3.
Mitochondrial disorders are inherited from the mother only.
Answer:

• Mitochondrial DNA becomes defective due to mutation.
• During fertilization, mitochondria are contributed by the egg cell (ovum) alone.
• Hence, mitochondrial disorders are inherited from the mother only.

Question 4.
Tobacco smoking causes cancer.
Answer:

• Tobacco smoke contains harmful chemicals like pyridine, ammonia, aldehyde furfural, carbon monoxide, nicotine, sulphur dioxide etc.
• They cause uncontrolled cell division.
• Tobacco smoke is full of minute carbon particles which cause normal tissue lining of the lung to transform into thickened black tissue. This leads to cancer.
• Therefore, tobacco smoking causes cancer.

Define the following terms:

Question 1.
Gene
Answer:
The segment of DNA which contains all the information for synthesis of a particular protein is called a ‘gene’.

Question 2.
Chromosome
Answer:
The structure in the nucleus of the cells that carries the hereditary characteristics is called chromosome.

Question 3.
Genetics
Answer:
The branch of biology which studies the transfer of characteristics of organism from one generation to the next and genes in particular, is called genetics.

Question 4.
Heredity
Answer:
Transfer of characteristics from parents to offsprings is called heredity.

Question 5.
Homologous chromosomes
Answer:
If the pair consists of chromosomes are similar in shape and organization, they are called homologous chromosomes.

Question 6.
Heterologous chromosomes
Answer:
If the pair which consists of chromosomes are not similar in shape and organization, they are called heterologous chromosomes.

Question 7.
Genetic disorders
Answer:
Diseases or disorders occuring due to abnormalities in chromosomes and mutations in genes are called genetic disorders.

Distinguish between:

Question 1.
DNA and RNA
Answer:

Question 2.
Turner syndrome and Klinefelter syndrome.
Answer:

Write short notes on:

Question 1.
Albinism
Answer:

• Albinism is a monogenic disorder.
• Our eyes, skin and hair have colour due to the brown pigment melanin. In this disease, the body cannot produce melanin.
• The skin becomes pale, hair are white and eyes are usually pink due to absence of melanin pigment in the retina and sclera.

Question 2.
Polygenic disorders.
Answer:

• Polygenic disorders are caused due to mutations in more than one gene.
• In most such cases, their severity increases due to effects of environmental factors on the foetus.’
• Common examples of such disorders are cleft lip, cleft palate, constricted stomach, spina bifida (a defect of the spinal cord), etc. Besides diabetes, blood pressure, heart disorders, asthma and obesity are also polygenic disorders.
• Polygenic disorders do not strictly follow Mendel’s principles of heredity.
• These disorders arise from a complex interaction between environment, life style and defects in several genes.

Question 3.
Turner syndrome.
Answer:

• Turner syndrome is a disorder arising in women due to abnormality in sex chromosomes.
• Turner syndrome arises due to either inheritance of only one X chromosome from parents or due to inactivation of the gender- related part of X-chromosomes.
• Instead of the normal 44 + XX condition, women suffering from Turner syndrome show a 44 + X condition.
• Such women are sterile i.e. unable to have children due to improper growth of the reproductive organ.

Answer the following questions:

Question 1.
What are the main objectives of National Health Mission?
Answer:
The main objectives of National Health Mission are:

• Strengthening of the rural and urban health facilities.
• Controlling various diseases and illnesses.
• Increasing public awareness about health.
• Offering financial assistance to patients through various schemes.

Question 2.
Which were the seven pairs of contrasting characteristics studied by Mendel in pea plant?
Answer:
The seven pairs of contrasting characters studied by Mendel in pea plant were as follows:

Question 3.
Name some dominant and recessive characteristics seen in human beings.
Answer:
Some dominant and recessive characteristics of human beings.

Question 4.
What is Klinefelter syndrome?
Answer:

• Klinefelter syndrome is a disorder arising in men due to abnormalities in sex chromosomes.
• In this disorder, men have one extra X chromosome, hence their chromosomal condition becomes 44 + XXY.
• Such men are usually sterile because their reproductive organs are not well developed.

Question 5.
How is the diagnosis for sickle-cell anaemia made?
Answer:

• Under the National Health Mission scheme, the ‘Solubility Test’ for diagnosis of sickle-cell anaemia is available at all district hospitals.
• Similarly, the confirmatory diagnostic test – ‘Electrophoresis’ is performed at rural and subdistrict hospitals.

Question 6.
Find out the Phenotypic ratio of the following:
(a) Round-Yellow
(b) Wrinkled-Yellow
(c) Round-Green
(d) Wrinkled-Green
Answer:
(a) Round-Yellow: 9
(b) Wrinkled-Yellow: 3
(c) Round-Green: 3
(d) Wrinkled-Green: 1
Phenotypic ratio: 9:3:3:1

Question 7.
Find out the Genotypic ratio of the following:
(a) RRYY
(b) RRYy
(c) RRyy
(d) RrYY
(e) RrYy
(f) Rryy
(g) rrYY
(h) rrYy
(i) rryy
Answer:
(a) RRYY -1
(b) RRYy-2
(c) RRyy-1
(d) RrYY-2
(e) RrYy-4
(f) Rryy-2
(g) rrYY – 1
(h) rrYy – 2
(i) rryy – 1
Genotypic ratio: 1:2:1:2:4:2:1:2:1

Draw neat and labelled diagrams of the following:

Question 1.
Structure of chromosome
Answer:

Question 2.
Types of RNA
Answer:

Answer the following questions:

Question 1.
What are the effects of tobacco consumption?
Answer:

• Smoking of cigarettes and bidis adversely affects the process of digestion.
• It causes a burning sensation in the throat and cough.
• Excessive smoking causes instability and trembling of fingers.
• It causes dry cough which leads to sleeplessness.
• Tobacco consumption can lead to shortening of life span, chronic bronchitis, pericarditis, cancer of the lungs, mouth, larynx (voice box), pharynx, urinary bladder, lips or tongue.
• The nicotine present in tobacco affects the central and peripheral nervous system. Arteries become hard i.e. it causes arteriosclerosis and hypertension.

Question 2.
Complete the table for number of chromosomes in different organisms.
Answer:

Balbharati Maharashtra State Board 9th Std Science Textbook Solutions 

• Information Communication Technology (ICT) Class 9 Science Textbook Solutions
• Reflection of Light Class 9 Science Textbook Solutions
• Study of Sound Class 9 Science Textbook Solutions
• Carbon: An Important Element Class 9 Science Textbook Solutions
• Substances in Common Use Class 9 Science Textbook Solutions
• Life Processes in Living Organisms Class 9 Science Textbook Solutions
• Heredity and Variation Class 9 Science Textbook Solutions
• Introduction to Biotechnology Class 9 Science Textbook Solutions
• Observing Space: Telescopes Class 9 Science Textbook Solutions

Std 9 Science Chapter 7 Energy Flow in an Ecosystem Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 7 Energy Flow in an Ecosystem Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Question Answer Maharashtra Board

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Textbook Questions and Answers

1. Complete the following table (Carefully study the carbon, oxygen and nitrogen cycles).

2. Correct and rewrite the following statements and justify your corrections.
a. Carnivores occupy the second trophic level in the food chain.
b. The flow of nutrients in an ecosystem is considered to be a ‘one-way’ transport.
c. Plants in an ecosystem are called primary consumers.

3. Give reasons.
a. Energy flow through an ecosystem is ‘one way’.
Answer:

• The Sun is the most important source of energy in any ecosystem.
• Green plants of the ecosystem store some amount of solar energy in the form of food.
• Before reaching the decomposers, this energy is passed on from one trophic level to the next.
• Decomposers dissipate some amount of energy in the form of heat.
• However, no part of the energy ever returns to the Sun. Hence, energy flow through an ecosystem is ‘one way’.

b. Equilibrium is necessary in the various bio-geo-chemical cycles.
Answer:

• The cyclic flow of nutrients within an ecosystem is called bio-geo-chemical cycles.
• Nutrients, necessary for the growth of organisms are continuously transferred from abiotic to biotic factors and biotic to abiotic factors within an ecosystem.
• Any imbalance in the cycles will break the link between the biotic and abiotic factors.
• Therefore, equilibrium is necessary between bio-geo-chemical cycles.

c. Flow of nutrients through an ecosystem is cyclic.
Answer:

• All organisms need nutrients for their growth.
• The nutrients carbon, oxygen, nitrogen, iron, calcium etc. are circulated and recycled from the biosphere to living organisms and after their death back to the biosphere.
• Nutrients are taken up by plants and then passed on to the consumers.
• Eventually, after their death, all types of consumers, are decomposed by decomposers like bacteria and fungi and the nutrients are again released into the biosphere and are, used again by living organisms.

Therefore, the flow of nutrients through an ecosystem is cyclic.

4. Explain the following cycles in your own words with suitable diagrams.
a. Carbon cycle.

Answer:

• The circulation and recycling of carbon from the atmosphere to living organisms and after their death back to the atmosphere is called the carbon cycle.
• Abiotic carbon atoms are circulated and recycled into biotic form mainly through photosynthesis and respiration.
• Hence, the carbon cycle is one of the important bio-geochemical cycles.
• Plants convert carbon dioxide into carbohydrates by the process of photosynthesis.
• Similarly, they produce carbon compounds like proteins and fats, too.
• Carnivores feed upon herbivores. In this way, biotic carbon is transported from plants to herbivores, from herbivores to carnivores and from carnivores to apex consumers.
• Main processes in the carbon cycle
  
• Eventually, after death, all types of consumers, are decomposed by decomposers like bacteria and fungi and carbon dioxide is released again into the atmosphere and is used again by living organisms.
• In this way, carbon is continuously passed on from one living organism to another. After the death of living organisms, carbon goes to the atmosphere and is again taken up by living organisms.

b. Nitrogen cycle.
Answer:

• Nitrogen forms 78% i.e. the maximum portion of the atmosphere. It is necessary for the maintenance of the cycle of nature.
• The circulation and recycling of nitrogen gas into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
• All organisms participate in the nitrogen cycle. It is an important component of proteins and nucleic acids.
• As compared to other elements, it is inactive and does not easily combine with other elements. Most organisms cannot use the free form of nitrogen.
• Important processes of nitrogen cycle:
  (a) Nitrogen fixation: Conversion of nitrogen into nitrates and nitrites through atmosphere, industrial and biological processes.
  (b) Ammonification: Release of ammonia through the decomposition of dead bodies and excretory wastes of organisms.
  (c) Nitrification: Conversion of ammonia into a nitrite and then nitrate.
  (d) Denitrification: Conversion of nitrogen compounds into gaseous nitrogen.

c. Oxygen cycle.
Answer:

1. Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere. The circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
2. This cycle, includes both the biotic and abiotic components. Oxygen is continuously produced as well as used up in the atmosphere.
3. Oxygen is highly reactive and it readily reacts with other elements and compounds.
4. As oxygen is found in various forms like molecular oxygen (Oz), water (H,0), carbon dioxide (C02), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
5. Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

5. What would you do to help maintain the equilibrium in the various bio-geochemical cycles? Explain in brief.
Answer:

• Bio-geo-chemical cycles always involve the achievement of equilibrium, i.e., a balance in the cycling of the nutrients between the spheres.
• Human activities that are known to be environmentally unfriendly can disrupt this balance.
• We should avoid deforestation as trees play an important role in maintaining the balance.
• We should avoid overuse of fertilizers. The fertilizers get washed away in the nearby water bodies disrupting the balance.
• Avoid burning of fossil fuels as these fuels release a large amount of carbon in the form of carbondioxide, thus disrupting the balance.
• Vehicular emissions is another contributor to the disruption in balance of the various cycles.
• These emissions release oxides of nitrogen and carbon and other hazardous air pollutants.
• So, we must use better quality fuel like CNG or ethanol to reduce vehicular emissions.

6. Explain in detail the inter-relationship between the food chain and food web.
Answer:

• Interaction go on continuously between producers, consumers and decomposers.
• There is a definite sequence in these interactions which is called the food chain.
• Each chain consists of four, five or more links.
• An ecosystem consists of many food chains that are interconnected at various levels. Thus, a food web is formed.
• An organism may be the prey for many other organisms.
• For example, an insect feeds upon leaves of various plants but the same insect is the prey for different animals like frog, wall lizard, birds, etc.
• Thus, many food chains interconnected together form an intricate web called as food web.

7. State the different types of bio-geochemical cycles and explain the importance of those cycles.
Answer:

• The different types of bio-geo-chemical cycles are nitrogen, oxygen, carbon, water vapour, iron, calcium, phosphorus, etc.
• Nutrients, necessary for the growth of the organisms are continuously transferred from abiotic to biotic factors and biotic to abiotic factors within an ecosystem.
• These cycles operate continuously through the medium of the biosphere formed by the lithosphere, atmosphere and hydrosphere.
• (iv) The recycling of biological, geological and chemical sources of nutrients takes place through these cycles.
• Nutrients from the biosphere enter the bodies of plants and animals. Eventually, after death, all types of consumers are decomposed by decomposers like bacteria and fungi and they are again released into the biosphere and are used again by living organisms.
• Therefore, these cycles help in maintaining the flow of nutrients and energy through ecosystem and maintaining the equilibrium in the ecosystem.

8. Explain the following with suitable examples.
a. What type of changes occur in the amount of energy during its transfer from plants to apex consumers?
Answer:

• Plants of the ecosystem store some of the solar energy in the form of food.
• Before reaching the decomposers, this energy is passed on from one trophic level to the next.
• At every trophic level, some amount of energy is used by the organism for its own life processes and some amount of energy is lost to the surroundings.
• Decomposers dissipate some amount of energy in the form of heat.
• However, no part of the energy ever returns to the Sun. Hence, such passage of energy is referred to as ‘one way’ transport.
• Therefore, energy is maximum at the base of the pyramid and is least at the apex, e.g.
• phytoplanktons which form the base of the pyramid have 10,000 kcal of energy while humans at the apex have 10 kcal of energy.

b. What are the differences between flow of matter and of energy in an ecosystem? Why?
Answer:

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Intext Questions and Answers

Can you recall?

7 Energy Flow In An Ecosystem Exercises  Question 1.
What is meant by nitrogen fixation?
Answer:
The process of conversion of Nitrogen into nitrates and nitrites is called Nitrogen fixation.

Energy Flow In An Ecosystem Class 9 Questions And Answers Question 2.
Which microbes bring about the process of nitrogen fixation?
Answer:
Rhizobium present in the root nodules of the leguminous plant bring about the process of nitrogen fixation.

Class 9 Science Chapter 7 Energy Flow In An Ecosystem Question 3.
What is meant by ‘ecosystem’?
Answer:
An ecosystem includes all of the living things like plants, animals and other organisms in a given area, interacting with each other and also with non-living environmental factors like weather, earth, sun, soil, climate and atmosphere.

Energy Flow In An Ecosystem Class 9 Exercise 1Question 4.
Which are different types of ecosystems?
Answer:

Class 9 Science Chapter 7 Energy Flow In An Ecosystem Exercise Question 5.
How do interactions take place between biotic and abiotic factors of an ecosystem?
Answer:

• Abiotic factors include non-living factors such as soil, water etc. and biotic factors include all living organisms.
• Both these abiotic and biotic ecosystems are connected through various bio-geo-chemical cycles.
• These connections/interactions are important for the flow of matter and flow of energy.

Class 9 Science Chapter 7 Energy Flow in an Ecosystem Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
An intricate network of food chains is called
(a) Biosphere
(b) Food web
(c) Energy pyramid
(d) Ecosystem
Answer:
(b) food web

Question 2.
Fungi and other microbes are called
(a) Producers
(b) Consumers
(c) Decomposers
(d) Omnivores
Answer:
(c) decomposers

Question 3.
Oxygen forms of the atmosphere.
(a) 78%
(b) 21%
(c) 10%
(d) 90%
Answer:
(b) 21%

Question 4.
Microbes which do not need oxygen are called
(a) Producers
(b) Aerobes
(c) Anaerobes
(d) Decomposers
Answer:
(c) anaerobes

Question 5.
The pattern of energy exchange in an ecosystem is called a
(a) Food chain
(b) Food web
(c) Pyramid of energy
(d) Trophic levels
Answer:
(c) Pyramid of energy

Question 6.
Carbon atoms are circulated and recycled through
(a) Nitrification and denitrification
(b) Photosynthesis and respiration
(c) Respiration and nitrification
(d) Photosynthesis and ammonification
Answer:
(b) photosynthesis and respiration

Question 7.
Conversion of ammonia into a nitrite and then nitrate is called
(a) Nitrogen fixation
(b) Denitrification
(c) Nitrification
(d) Ammonification
Answer:
(c) nitrification

Question 8.
The conversion of nitrogen compounds into gaseous nitrogen is called
(a) Nitrogen fixation
(b) Denitrification
(c) Ammonification
(d) Nitrification
Answer:
(b) denitrification

Question 9.
is an important component of proteins and nucleic acids.
(a) Carbon
(b) Nitrogen
(c) Phosphorus
(d) Oxygen
Answer:
(b) Nitrogen

Question 10.
Amount of matter and energy from the lowest level to the highest level.
(a) decreases
(b) increases
(c) remains the same
(d) multiplies
Answer:
(a) decreases

Question 11.
is the most important source of energy in any ecosystem.
(a) The Sun
(b) The Moon
(c) Producers
(d) Decomposers
Answer:
(a) The Sun

Question 12.
Flow of energy in an ecosystem is
(a) cyclical
(b) two way transport
(c) o ne way transport
(d) to and fro transport
Answer:
(c) one way transport

Question 13.
The Indian Institute of Ecology and Environment, Delhi, has published
(a) Invasive species in a changing Environment
(b) Encyclopaedia of Ecology and Environment
(c) Environment and Ecology Magazine
(d) Biodiversity and Disaster Management
Answer:
(b) Encyclopaedia of Ecology and Environment

Question 14.
Oxygen is released in the process of
(a) Respiration
(b) Decomposition
(c) Combustion
(d) Photosynthesis
Answer:
(d) photosynthesis

Question 15.
cycle is a gaseous cycle.
(a) Carbon
(b) Phosphorus
(c) Calcium
(d) Iron
Answer:
(a) Carbon

Question 16.
is a sedimentary cycle.
(a) Carbon
(b) Nitrogen
(c) Oxygen
(d) Calcium
Answer:
(d) Calcium

Question 17.
is a primary consumer.
(a) Elephant
(b) Frog
(c) Owl
(d) Tiger
Answer:
(a) Elephant

Question 18.
is a secondary consumer.
(a) Grasshopper
(b) Elephant
(c) Frog
(d) Human
Answer:
(c) Frog

Question 19.
Tiger is a /an
(a) Producer
(b) Primary consumer
(c) Apex consumer
(d) Secondary consumer
Answer:
(c) apex consumer

Question 20.
Carbon dioxide is released into the atmosphere through
(a) burning of fossil fuels
(b) volcanic activity
(c) respiration
(d) all of these
Answer:
(d) all of these

Question 21.
in 1942 studied the food chain and energy flow through it
(a) Linderman
(b) Darwin
(c) Calypso
(d) Chu win lee
Answer:
(a) Linderman

Question 22.
fter the death of apex consumers, energy becomes available to.
(a) Decomposers
(b) Producers
(c) Herbivores
(d) Carnivores
Answer:
(a) Decomposers

Question 23.
Green plants of the ecosystem store in the form of food.
(a) Solar energy
(b) Chemical energy
(c) Thermal energy
(d) Electrical energy
Answer:
(a) Solar energy

Question 24.
Plants convert carbon dioxide into by the process of photosynthesis.
(a) Carbohydrates
(b) Proteins
(c) Fats
(d) Vitamins
Answer:
(a) Carbohydrates

Question 25.
Carnivores feed upon
(a) Decomposers
(b) Herbivores
(c) Producers
(d) Secondary producers
Answer:
(b) Herbivores

Question 26.
is used up in the processes like respiration, combustion, decomposition, corrosion, rusting, etc.
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Helium
Answer:
(b) Oxygen

Question 27.
Nitrogen forms % of the atmosphere.
(a) 79
(b) 78
(c) 21
(d) 2
Answer:
(b) 78

Question 28.
Most organisms cannot use the free form of
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Carbon monoxide
Answer:
(b) Nitrogen

Question 29.
first proposed the concept of Ecological Pyramid in 1927.
(a) Darwin
(b) Newton
(c) Elton
(d) Edison
Answer:
(c) Elton

Question 30.
Ecological Pyramid is called
(a) Hills
(b) Mounts
(c) Eltonian
(d) Darwinism
Answer:
(c) Eltonian

Question 31.
is produced from oxygen through various atmospheric processes.
(a) Nitrogen dioxide
(b) Nitrites
(c) Ozone
(d) CFC
Answer:
(c) Ozone

Question 32.
Interactions between producers, consumers and saprophytes in a definite sequence is called
(a) Links
(b) Internet
(c) Food chain
(d) Connectors
Answer:
(c) Food chain

Question 33.
Many food chains interconnected at various levels is called
(a) Links
(b) Internet
(c) Connectors
(d) Food web
Answer:
(d) Food web

Question 34.
Decomposers dissipate some amount of energy in the form of
(a) Light
(b) Electricity
(c) Sound
(d) Heat
Answer:
(d) Heat

Question 35.
The flow of nutrients in an ecosystem is
(a) Non- cyclic
(b) Mono directional
(c) Reverse directional
(d) Cyclical
Answer:
(d) Cyclical

Question 36.
The cyclical flow of nutrients within an ecosystem is called
(a) Biological cycle
(b) Chemical cycle
(c) Solar cycle
(d) Bio-geo chemical cycle
Answer:
(d) Bio-geo chemical cycle

Question 37.
is an accumulation of the main abiotic gaseous nutrient materials found in the earth’s atmosphere.
(a) Gaseous cycle
(b) Water cycle
(c) Solar cycle
(d) Lunar cycle
Answer:
(a) Gaseous cycle

Question 38.
Oxygen is released into the atmosphere by the process of
(a) Photosynthesis
(b) Respiration
(c) Oxidation
(d) Decomposition
Answer:
(a) Photosynthesis

Question 39.
Charles Elton studied the of the Beer islands in England..
(a) Tundra ecosystem
(b) Mediterranean ecosystem
(c) Equatorial ecosystem
(d) Taiga ecosystem
Answer:
(a) Tundra ecosystem

Question 40.
in 1942 studied the food chain and energy flow through it.
(a) Charles Elton
(b) Lindeman
(c) Robert Whittaker
(d) Eichler
Answer:
(b) Lindeman

Question 41.
After the death of apex consumers, energy becomes available to
(a) Primary consumer
(b) Secondary consumer
(c) Decomposer
(d) Sun
Answer:
(c) Decomposer

Question 42.
Nitrogen forms % of the atmosphere.
(a) 28%
(b) 78%
(c) 48%
(d) 82%
Answer:
(b) 78%

Question 43.
first proposed the concept of the Ecological Pyramid in 1927.
(a) Charles Elton
(b) Lindeman
(c) Eichler
(d) John Muir
Answer:
(a) Charles Elton

Question 44.
Oxygen is released into the atmosphere by the process of
(a) respiration
(b) Photosynthesis
(c) Combustion
(d) All of these
Answer:
(b) Photosynthesis

Find the odd man out:

Question 1.
Photosynthesis, Respiration, Decomposition, Forest Fires
Answer:
Forest Fires

Question 2.
Combustion, Corrosion, rusting, formation of ozone, Photosynthesis
Answer:
Photosynthesis

Question 3.
Biological nitrogen fixation, ammonification, nitrification, denitrification, industrial nitrogen fixation
Answer:
Industrial nitrogen fixation

Question 4.
Frog, Owl, Squirrel, Fox
Answer:
Squirrel

Question 5.
Grasshopper, squirrel, elephant, lion
Answer:
Lion

Question 6.
Nitrogen cycle, oxygen cycle, carbon cycle, phosphorus cycle
Answer:
Phosphorus cycle

Question 7.
Photosynthesis, Nitrification, Ammonification, Denitrification
Answer:
Photosynthesis

Find out the correlation:

1. Grasshopper : Primary consumer :: Tiger : ………………..
2. Owl : Secondary consumer :: Squirrel : ………………..
3. Flow of energy : One way :: Flow of nutrients : ………………..
4. Plants : Producers :: Bacteria and Fungi : ………………..
5. Nitrogen : Gaseous cycle :: Phosphorus : ………………..
6. Oxygen : 21% :: Nitrogen : ………………..
7. Photosynthesis: Carbon cycle:: Ammonification : ………………..
8. Respiration : Oxygen cycle :: Nitrification : ………………..
9. Respiration : Biotic process :: Combustion : ………………..
10. Microbes using oxygen : Aerobes :: Microbes not using oxygen : ………………..
Answer:
(1) Apex consumer
(2) Primary consumer
(3) Cyclic
(4) Decomposers
(5) Sedimentary cycle
(6) 78%
(7) Nitrogen cycle
(8) Nitrogen cycle
(9) Abioticprocess
(10) Anaerobes

Q.l. (B) 3. Difference between:
(1) Azotobacter and Rhizobium
Answer:

(2) Biotic components and Abiotic component
Answer:

(3) Producers and Herbivores
Answer:

(4) Carnivores and Herbivores
Answer:

(5) Phosphorus and Carbon
Answer:

(6) Food chain and Food web
Answer:

State whether the following statements are true or false. Correct the false statements:

(1) Herbivores occupy the third trophic level in a food chain.
(2) Apex consumers use herbivores and carnivores as their food.
(3) Humans are apex consumers.
(4) Omnivores feed only on carnivores.
(5) A food chain has two links.
(6) The number of consumers in a food web is fixed.
(7) The amount of matter and energy goes on increasing at every level in a food chain.
(8) Robert Brown first proposed the concept of Ecological Pyramid.
(9) After the death of apex consumers, the energy becomes available to decomposers.
(10) The gaseous cycle is a speedier cycle than the sedimentary cycle.
(11) Climatic changes and human activities seriously affect the speed, intensity and equilibrium of bio-geo-chemical cycles.
(12) Carbon dioxide is released in the atmosphere through photosynthesis.
(13) The equilibrium of oxygen and carbon dioxide gases is maintained by decomposers.
(14) The conversion of ammonia into a nitrite and then nitrate is called nitrogen fixation.
(15) Conversion of nitrogen compounds into gaseous nitrogen is called nitrogen fixation.
(16) Release of ammonia through decomposition of dead plants and excretory wastes of organisms is called ammonification.
(17) The cyclic flow of nutrients within an ecosystem is called Energy Pyramid.
Answer:
(1) False, herbivores occupy the second trophic level in a food chain as they are directly dependent on producers.
(2) True
(3) True
(4) False. Omnivores feed on both herbivores and carnivores.
(5) False. A food chain consists of four, five or more links.
(6) False. A food web can have many consumers.
(7) False. The amount of matter and energy goes on decreasing at every level in a food chain.
(8) False. Charles Elton first proposed the concept of Ecological Pyramid.
(9) True
(10) True
(11) True
(12) False. Carbon dioxide is released in the atmosphere through respiration, burning of fossil fuels and wood, forest fires and volcanic activity. (13) False. The equilibrium of oxygen and carbon dioxide gases is maintained by plants.
(14) False. The conversion of ammonia into a nitrite and then nitrate is called nitrification.
(15) False. Conversion of nitrogen compounds into gaseous nitrogen is called denitrification.
(16) True
(17) False. The cyclic flow of nutrients within an ecosystem is called bio-geochemical cycle.

Name the following:

Question 1.
The animals that feed on herbivores.
Answer:
Carnivores.

Question 2.
Organisms that feed on herbivores and carnivores.
Answer:
Omnivores.

Question 3.
Two examples of primary consumers.
Answer:
Grasshopper, squirrel.

Question 4.
Two examples of secondary consumers.
Answer:
Frog, owl.

Question 5.
Two examples of Apex consumers.
Answer:
Lion, tiger.

Question 6.
Levels in the food chain.
Answer:
Trophic level.

Question 7.
Organisms that decompose the dead bodies of plants and animals.
Answer:
Decomposers.

Question 8.
Process which releases oxygen.
Answer:
Photosynthesis.

Question 9.
Release of ammonia through decomposition of dead bodies and excretory wastes of organisms.
Answer:
Ammonification.

Question 10.
Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes.
Answer:
Nitrogen fixation.

One line answers:

Question 1.
What is Food chain?
Answer:
Interactions between producers, consumers and decomposers in a definite sequence is called as a food chain.

Question 2.
What is Food web?
Answer:
The interconnection among different food chains in an ecosystem at various levels is called as a food web.

Question 3.
What is Trophic level?
Answer:
A trophic level is the step at which the organism obtains its food in the chain.

Question 4.
What is Pyramid of energy?
Answer:
The pattern of energy exchange in an ecosystem is called a ‘Pyramid of energy’.

Question 5.
What is Bio-geo-chemical cycle?
Answer:
The cyclical flow of nutrients within an ecosystem is called bio-geo-chemical cycle.

Question 6.
What is Carbon cycle?
Answer:
The circulation and recycling of carbon from the atmosphere to living organisms and aher their death back to the atmosphere is called the carbon cycle.

Question 7.
What is Oxygen cycle?
Answer:
The circulation and recycling of oxygen within the biosphere is called as oxygen cycle.

Question 8.
What is Nitrogen cycle?
Answer:
The circulation and recycling of nitrogen gas into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.

Question 9.
What is Nitrogen fixation?
Answer:
The process of conversion of free nitrogen gas of the atmosphere into nitrogen compounds is called of nitrogen fixation.

Distinguish between:

Question 1.
Gaseous Cycle and Sedimentary Cycle.
Answer:

Question 2.
Carbon Cycle and Nitrogen Cyde.
Answer:

Complete the flow chart:

Question 1.
Energy Pyramid.

Question 3.
Nitrogen Cycle

Question 4.
Bio-Geo Chemical cycle

Write short notes on:

Question 1.
Trophic level.
Answer:

• Each level in the food chain is called a trophic level.
• A trophic level is the step at which the organism obtains its food in the chain.
• The amount of matter and energy gradually decreases from producers at the lowest level to the top consumers at the highest level.

Question 2.
Food web.
Answer:

• An ecosystem consists of many food chains that are interconnected at various levels. This is called food web.
• An organism may be the prey for many other organisms.
• For example, an insect feeds upon leaves of various plants but the same insect is the prey for different animals like wall lizards, birds etc.
• This forms an intricate web instead of a linear food chain. Such an intricate network is called as food web.
• Generally food webs are formed everywhere in nature.

Question 3.
Energy Pyramid.

Answer:

• Each level in the food chain is called a trophic level.
• The amount of matter and energy gradually decreases from producers at the lowest level to the top consumers at the highest level.
• The initial quantity of energy goes on decreasing at every level of energy exchange.
• Similarly, the number of organisms also decreases from the lowest level to the highest level.
• This pattern of energy exchange in an ecosystem is called a Pyramid of energy.

Explain the following statements

Question 1.
justify the statements
(a) Producers form the first trophic level in the food chain. Herbivores depend directly on producers.
(b) The flow of nutrients in an ecosystem is cyclic.
(c) Plants in an ecosystem are called autotrophs.
Answer:

1. So herbivores form the second trophic level, whereas carnivores depend on herbivores, so they form the third trophic level in the food chain.
2. The nutrients are circulated and recycled from the biosphere to living organisms and after their death back to the biosphere.
3. They produce their own food by the process of photosynthesis. All animals in an ecosystem directly or indirectly depend on plants for food.

Explain the diagram

Question 1.
Food chain in a forest ecosystem:

Answer:

• In a forest ecosystem, grass is eaten by a deer, which in turn is eaten by a tiger.
• The grass, deer and tiger form a food chain.
• In this food chain, energy flows from the grass (producer) to the deer (primary consumer) to the tiger (secondary consumer).

Question 2.
Food chain in an aquatic ecosystem (Pond)

Answer:

• In a aquatic ecosystem algae are eaten by insects.
• Insects are eaten by small fish, small fish are in turn eaten by big fish.
• And the big fish are eaten by fish eating birds.
• In this food chain, energy flows from the algae (producer) to the insects (primary consumers) to the small fish (secondary consumers) to the big fish (tertiary consumer) and to the fish eating birds (apex consumer).

Question 3.
Carbon cycle

Answer:

• The circulation and recycling of carbon from the atmosphere to living organisms and after their death back to the atmosphere is called carbon cycle.
• Main processes involved in carbon cycle are photosynthesis and respiration.
• Carbon in the form of carbon dioxide is directly absorbed by plants for photosynthesis

Question 4.
Nitrogen cycle

Answer:
(i) The circulation and recycling of nitrogen into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
(ii) Main processes involved in nitrogen cycle are nitrogen fixation, ammonification, nitrification and denitrification.
(iii) Nitrogen gas cannot be directly absorbed by plants. So nitrogen is fixed by the process of nitrogen fixation and then absorbed from the soil.

Question 5.
Oxygen cycle

Answer:

1. Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere.
2. Circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
3. This cycle, includes both the biotic and abiotic components.
4. Oxygen is continuously produced as well as used up in the atmosphere.
5. Oxygen is highly reactive and it readily reacts with other elements and compounds.
6. As oxygen is found in various forms like molecular oxygen (O₂), water (H₂O), carbon dioxide (CO₂), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
7. Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

Answers based on figures.

Question 1.
Nitrogen Cycle

Answer:

• Oxygen forms 21% of the atmosphere. It is also present in the hydrosphere and lithosphere.
• The circulation and recycling of oxygen within the biosphere is called the oxygen cycle.
• This cycle, includes both the biotic and abiotic components.
• Oxygen is continuously produced as well as used up in the atmosphere.
• Oxygen is highly reactive and it readily reacts with other elements and compounds.
• As oxygen is found in various forms like molecular oxygen (O₂), water (H₂O), carbon dioxide (CO₂), inorganic compounds etc, the oxygen cycle of the biosphere is extremely complex.
• Oxygen is released in the process of photosynthesis, whereas it is used up in processes like respiration, combustion, decomposition, corrosion, rusting, etc.

Answers based on figures.

Question 1.
Nitrogen Cycle

(i) Is nitrogen a reactive gas?
Answer:
Nitrogen in its atmospheric state non-reactive gas

(ii) Name process of nitrogen conversion from atmosphere to green plants.
Answer:
Nitrogen fixation is the process of nitrogen conversion atmosphere to green plants

(iii) Name the process of converting usable nitrogenous products into atmospheric inert nitrogen.
Answer:
Denitrification is the process of converting usable nitrogenous products into atmospheric inert nitrogen

(iv) Animals produce which product of nitrogen?
Answer:
Animals produce ammonia as a product of nitrogen

(v) Name two nitrifying organisms.
Answer:
Azotobacter and Rhizobium are the two nitrifying organisms

(vi) Which type of bio-geo-chemical cycles does nitrogen follow?
Answer:
Nitrogen follows gaseous and sedimentary bio-geo-chemical cycles

Question 2.
Carbon cycle

(i) Is carbon dioxide gas freely available in the atmosphere?
Answer:
Carbon dioxide gas is freely available in the atmosphere

(ii) How is carbon found in water?
Answer:
Carbon is found in water in the form of carbonates

(iii) How are we using carbon as a fuel?
Answer:
Fossil fuels are a form of carbon which are used as fuel by us

(iv) How to plants use carbon as their food source?
Answer:
Plants take up carbon in photosynthesis and convert it into starch which is their food source

(v) How do animals use carbon?
Answer:
Animals use carbon in form of organic compounds and inorganic compounds

(vi) Which type of bio-geo-chemical cycles does carbon follow?
Answer:
Carbon follows gaseous and sedimentary bio-geo-chemical cycles

Question 3.
Oxygen cycle

(i) Is oxygen gas freely available in the atmosphere?
Answer:
Oxygen gas is freely available in the atmosphere

(ii) How is oxygen used by animals?
Answer:
Oxygen is used in respiration by the animals

(iii) How are we using carbon as a fuel?
Answer:
Fossil fuels are a form of carbon which are used as fuel by us

(iv) How to plants use carbon as their food source?
Answer:
Plants take up carbon in photosynthesis and convert it into starch which is their food source

(v) How do animals use carbon?
Answer:
Animals use carbon in form of organic compounds and inorganic compounds

(vi) Which type of bio-geo-chemical cycles does carbon follow?
Answer:
Carbon follows gaseous and sedimentary biogeo-chemical cycles

Question 4.
Food web

(i) What is the basic unit of food web?
Answer:
The basic unit of food web is food chain

(ii) Which organisms are on the 1st level of this food web?
Answer:
Producers are p. the 1st level of this food web

(iii) What are the animals which depend on producers directly for nutrition called?
Answer:
The animals which depend on producers directly for nutrition are called Herbivores

(iv) What are the animals which eat any type of food for nutrition called?
Answer:
The animals which eat any type of food for nutrition are called Omnivore

(v) What will happen if one animal in the food chain goes extinct?
Answer:
If one animal in the food chain goes extinct the entire food chain collapse

(vi) What are the factors badly affecting the food web?
Answer:
Factors like hunting, pollution, deforestation, human-animal conflicts etc. are the factors badly affecting the food web

Complete the paragraph

(1) Elemental oxygen is normally found in the form of a diatomic molecule. However, in the upper reaches of the atmosphere, a molecule containing three atoms of oxygen is found. This would mean a formula of 03 and this is called ozone. Unlike the normal diatomic molecule of oxygen, ozone is poisonous and we are lucky that it is not stable nearer to the Earth’s surface. But it performs an essential function where it is found. It absorbs harmful radiations from the Sun. This prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life.

Recently it was discovered that this ozone layer was getting depleted. Various man-made compounds like CFCs (carbon compounds having both fluorine and chlorine) which are very stable and not degraded by any biological process) were found to persist in the atmosphere. Once they reached the ozone layer, they would react with the ozone molecules. This resulted in a reduction of the ozone layer and recently they have discovered a hole in the ozone layer above the Antarctica. It is difficult to imagine the consequences for life on Earth if the ozone layer dwindles further, but many people think that it would be better not to take chances. These people advocate working towards stopping all further damage to the ozone layer.

(2) The utilisation of glucose to provide energy to living things involves the process of respiration in which oxygen may or may not be used to convert glucose back into carbon dioxide. This carbon dioxide then goes back into the atmosphere. Another process that adds to the carbon dioxide in the atmosphere is the process of combustion where fuels are burnt to provide energy for various needs like heating, cooking, transportation and industrial processes.

In fact, the percentage of carbon dioxide in the atmosphere is said to have doubled since the industrial revolution when human beings started burning fossil fuels on a very large scale. Carbon, like water, is thus cycled repeatedly through different forms by the various physical and biological activities. Heat is trapped by glass, and hence the temperature inside a glass enclosure will be much higher than the surroundings. This phenomenon was used to create an enclosure where tropical plants could be kept warm during the winters in colder climates. Such enclosures are called greenhouses.

Greenhouses have also lent their name to an atmospheric phenomenon. Some gases prevent the escape of heat from the Earth. An increase in the percentage of such gases in the atmosphere would cause the average temperatures to increase worldwide and this is called the greenhouse effect. Carbon dioxide is one of the greenhouse gases. An increase in the carbon dioxide content in the atmosphere would cause more heat to be retained by the atmosphere and lead to global warming.

(3) Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules essential to life like proteins, nucleic acids (DNA and RNA) and some vitamins. Nitrogen is found in other biologically important compounds such as alkaloids and urea too. Nitrogen is thus an essential nutrient for all life-forms and life would be simple if all these life-forms could use the atmospheric nitrogen directly. However, other than a few forms of bacteria, life-forms are not able to convert the comparatively inert nitrogen molecule into forms like nitrates and nitrites which can be taken up and used to make the required molecules.

These nitrogen-fixing bacteria may be free-living or be associated with some species of dicot plants. Most commonly, the nitrogenfixing bacteria are found in the roots of legumes (generally the plants which give us pulses) in special structures called root nodules. Other than these bacteria, the only other manner in which the nitrogen molecule is converted to nitrates and nitrites is by a physical process. During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain. These are then utilised by various lifeforms.

Read the paragraph and answer the questions:

(1) Nitrogen cycle
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification, The majority of Earth’s atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen.

However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition, Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health.

(i) Why nitrogen cycle is called bio-geochemical cycle?
Answer:
Nitrogen cycle is called bio-geochemical cycle as it undergoes biological as well as geochemical processes.

(ii) Why is nitrogen cycle important to us?
Answer:
Nitrogen cycle is important to us as nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition.

(iii) Name important process of nitrogen cycle.
Answer:
Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.

(iv) What can affect the nitrogen cycle negatively?
Answer:
Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health.

(v) Which human activities change the nitrogen cycle?
Answer:
Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle.

(2) Food web
A food chain is a linear network of links in a food i web starting from producer organisms (such asgrass or trees which use radiation from the Sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), ordecomposer species (such as fungi or bacteria), A food chain also shows how the organisms are related with each other by the food they eat. Each level of a food chain represents a different trophiclevel. A food chain differs from a food web, because the complex network of different animal’s feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time.

Natural interconnections between food chains make it a food web. A common metric usedto the quantify food web trophic structure is foodi chain length. In its simplest form, the length of a chain is the number of links between a trophici consumer and the base of the web and the meanchain length of an entire web is the arithmetic average of the lengths of all chains in a food web. The food chain is an energy source diagram. Many food webs have a keystone species. A keystonespecies is a species that has a large impact on thei surrounding environment and can directly affectthe food chain.

If this keystone species dies off it can set the entire food chain off balance. Keystonespecies keep herbivores from depleting all of thei foliage in their environment and preventing ai mass extinction. Food chains were first introduced by the Arab scientist and philosopher Al-Jahiz inthe 10th century and later popularized in a book I published in 1927 by Charles Elton, which also i introduced the food web concept.

(i) What is a food web?
Answer:
Food web is a linear network of links of food chains.

(ii) In a food web which organism are called producers?
Answer:
In a food web which organism which can produce food by photosynthesis are called producers.

(iii) What is the role of keystone species?
Answer:
Keystone species keep herbivores from depleting all of the foliage in their environment and preventing a mass extinction.

(iv) What is a keystone species?
Answer:
A keystone species is a species that has a large impact on the surrounding environment and can directly affect the food chain.

(v) What does each level of food chain represent?
Answer:
Each level of a food chain represents a different trophic level.

(3) Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone. Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to make Earth capable of sustaining life. It describes the movement of carbon as it is recycled and reused throughout the biosphere, as well as long-term processes of carbon sequestration to and release from carbon sinks.

The carbon cycle was discovered by Antoine! Lavoisier and Joseph Priestley, and popularised by Humphry Davy. Carbon in the Earth’satmosphere exists in two main forms carbon dioxide and methane. Both of these gases absorb and retain heat in the atmosphere and are partially responsible for the greenhouse effect. Methane produces a larger greenhouse effect per volume as compared to carbon dioxide, but it exists in much lower concentrations and is more short-lived than carbon dioxide, making carbon dioxide the more important greenhouse gas of the two.

Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres. Carbon dioxide also dissolves directly from the atmosphere into bodies of water (ocean, lakes, etc.), as well as dissolving in precipitation as raindrops fall through the atmosphere. When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid, which contributes to ocean acidity. It can then be absorbed by rocks through weathering. It also can acidify other surfaces it touches or be washed into the ocean.

(i) Which gas has greener house effect as compared to CO₂?
Answer:
Methane gas CH₄ has greener house effect as compared to CO₂.

(ii) How does dissolved CO₂ affect oceans?
Answer:
When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid, which contributes to ocean acidity.

(iii) Why is carbon cycle called bio-geochemical cycle?
Answer:
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

(iv) How is carbon dioxide removed from atmosphere?
Answer:
Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres.

(v) Who discovered the carbon cycle?
Answer:
The carbon cycle was discovered by Antoine Lavoisier and Joseph Priestley.

Answer the questions in detail:

Question 1.
Write the important processes of the nitrogen cycle.
Answer:

• Nitrogen fixation: Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes.
• Ammonification: Release of ammonia through decomposition of dead bodies and excretory wastes of organisms.
• Nitrification: Conversion of ammonia into a nitrite and then nitrate.
• Denitrification: Conversion of nitrogen components into gaseous nitrogen.

Make a concept diagram and explain.

Question 1.
Food chain

Answer:
According to the mode of nutrition the organisms are classified into producers, consumers, saprotrophs (saprophytes) and decomposers. Primary consumers are directly dependent on autotrophs (producers), e.g.: Grasshopper, squirrel, elephant) Secondary consumers use herbivores as their food, e.g.: Frog, owl, fox, etc. Apex or top consumers use herbivores and carnivores as their food. No animals feed on top consumers, e.g.: Tiger, lion, etc. Omnivores feed on herbivores and carnivores, e.g.: Humans, bear, etc. A continuous interaction between producers, consumers and decomposers in a definite sequence is called as food chain.

Food chain, in ecology is the sequence of transfers of matter and energy in the form of food from organism to organism. Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant. Plants, which convert solar energy to food by photosynthesis, are the primary food source. In a predator chain, a plant-eating animal is eaten by a flesh-eating animal. In a parasite chain, a smaller organism consumes part of a larger host and may itself be parasitized by even smaller organisms. In a saprophytic chain, microorganisms live on dead organic matter.

Question 2.
Energy pyramid
Answer:

An energy pyramid is a model that shows the flow of energy from one trophic, or feeding, level to the next in an ecosystem. The model is a diagram that compares the energy used by organisms at each trophic level. The energy in an energy pyramid is measured in units of kilocalories (kcal). Energy pyramids are similar to biomass pyramids, another type of trophic pyramid that models the amount of biomass at each trophic level in an ecosystem, energy flow in ecosystems. The structure of an energy pyramid reflects the trophic structure of an ecosystem.

The pyramid is divided into trophic levels similar to those in a food chain. At the pyramid base are the producers, autotrophic organisms that make their own food from inorganic substances. All of the other organisms in the energy pyramid are consumers. These are heterotrophs, meaning that they get food energy by consuming other organisms. The consumers at each trophic level feed on organisms from the level below and are themselves consumed by organisms at the level above. Primary consumers are organisms that consume producers; thus, most primary consumers are herbivores, though some may be detrivores (organisms that feed on decaying organic matter).

Secondary consumers are carnivores that feed on primary consumers and tertiary consumers are carnivores that eat secondary consumers. In rare instances, an ecosystem may have an additional trophic level composed of quaternary consumers camivores that consume tertiary consumers’ energy pyramid. The shape of an energy pyramid shows that the amount of food energy that enters each trophic level is less than the amount that entered the level below. Approximately 90 percent of the food energy that enters a trophic level is “lost” as heat when it is used by organisms to power the normal activities of life such as breathing and digesting food the remaining 10 percent is stored in the various organisms’ tissues.

It is this latter energy that is available to be passed to the next trophic level. Thus, the higher the trophic level on the pyramid, the lower the amounts of available energy ecosystem energy transfer through an ecosystem. The number of organisms at each level decreases relative to the level below because there is less energy available to support those organisms. The top level of an energy pyramid has the fewest organisms because it has the least amount of energy. Eventually there is not enough energy left to support another trophic level; thus most ecosystems only have four trophic levels.

Balbharati Maharashtra State Board 9th Std Science Textbook Solutions

• Laws of Motion Class 9 Science Textbook Solutions
• Work and Energy Class 9 Science Textbook Solutions
• Current Electricity Class 9 Science Textbook Solutions
• Measurement of Matter Class 9 Science Textbook Solutions
• Acids, Bases and Salts Class 9 Science Textbook Solutions
• Classification of Plants Class 9 Science Textbook Solutions
• Energy Flow in an Ecosystem Class 9 Science Textbook Solutions
• Useful and Harmful Microbes Class 9 Science Textbook Solutions
• Environmental Management Class 9 Science Textbook Solutions

Std 9 Science Chapter 5 Acids, Bases and Salts Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 5 Acids, Bases and Salts Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 5 Acids, Bases and Salts Question Answer Maharashtra Board

Class 9 Science Chapter 5 Acids, Bases and Salts Textbook Questions and Answers

1. Identify the odd one out and justify.

(a) Chloride, nitrate, hydride, ammonium
Answer:
Ammonium is the odd one out as it is a basic radical and rest all are acidic radicals. Generally, basic radicals are formed by the removal of electrons from the atom of metals such as Na⁺, Cu²⁺. But there are some exceptions, such as NH₄⁺.

(b) Hydrogen chloride, sodium hydroxide, calcium oxide, ammonia
Answer:
Hydrogen chloride is the odd one out. It is acidic and rest all are basic.

(c) Acetic acid, carbonic acid, hydrochloric acid, nitric acid
Answer:
Carbonic acid is the odd one out. It is a dibasic acid and rest are all monobasic acids.

(d) Ammonium chloride, sodium chloride, potassium nitrate, sodium sulphate
Answer:
Ammonium chloride is the odd one out, as it is made up of a strong acid and weak base and rest all are formed from strong acid and strong base.

(e) Sodium nitrate, sodium carbonate, sodium sulphate, sodium chloride
Answer:
Sodium carbonate is the odd one out, as it is made up of a weak acid and strong base, and rest all are formed from strong acid and strong base.

(f) Calcium oxide, magnesium oxide, zinc oxide, sodium oxide.
Answer:
Zinc oxide is the odd one out, as it is an amphoteric oxide, and rest all are basic oxides.

(g) Crystalline blue vitriol, crystalline common salt, crystalline ferrous sulphate, crystalline sodium carbonate.
Answer:
Crystalline common salt is the odd one out, as it does not contain water of crystallisation. It is an ionic compound and ionic compounds are crystalline in nature and rest all have their crystalline structure because of their water of crystallization.

(h) Sodium chloride, potassium hydroxide, acetic acid, sodium acetate.
Answer:
Acetic acid is the odd one out. It is an acid, the rest are all salts.

2. Write down the changes that will be seen in each instance and explain the reason behind it.

(a) 50ml water is added to 50ml solution of copper sulphate.

Answer:

• Copper sulphate solution is blue. It is a concentrated solution.
• When 50 ml of water is added to this concentrated solution, it becomes a diluted solution.
• The intensity of the blue colour is now different in this homogenous mixture.

(b) Two drops of the indicator phenolphthalein were added to 10ml solution of sodium hydroxide.

Answer:

• Sodiumhy droxide is a base and phenolphthalein is a synthetic indicator.
• Sodium hydroxide solution will turn pink if phenolphthalein is added to it.
• It is a test for identifying bases.

(c) Two or three filings of copper were added to 10ml dilute nitric acid and stirred.
Answer:
When copper metal reacts with dilute nitric acid, the metal does not displace hydrogen from the acid like reaction with other metals. Instead the reaction produces nitric oxide, (NO).

(d) A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.
Answer:
Blue litmus Paper:

• HCl is hydrochloric acid, so the blue litmus turns red.
• When equal amount of NaOH is added the colour again changes to blue and remains the same.

Red litmus paper:

• Red litmus paper shows no colour change in hydrochloric acid.
• When some amount of NaOH is added the colour changes to blue initially but when the amount of NaOH is sufficient the blue colour dissappears.
• Equal amounts of HC1 and NaOH results in the formation of NaCl, a salt, and the solvent water. This reaction is called the neutralization reaction.

(e) Magnesium oxide was added to dilute HCl and magnesium oxide was a added to dilute NaOH.
Answer:
(i) Magnesium oxide + dil HCl.
This is a neutralization reaction. Magnesium oxide is an insoluble base, it reacts with dilute HCl to produce a soluble salt MgCl₂ and water H₂O.
\(\mathrm{MgO}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow \mathrm{MgCl}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(n)}\)

(ii) Magnesium oxide + NaOH.
No chemical reaction takes place between magnesium oxide and sodium hydroxide.

(f) Zinc oxide was added to dilute HCl and zinc oxide was added to dilute NaOH.
Answer:

• Zinc oxide reacts with dilute hydrochloric acid to form zinc chloride and water. It is a neutralization reaction.
  \(\mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow \mathrm{ZnCl}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)
• Zinc oxide reacts with sodium hydroxide to form sodium zincate and water.
  \(\mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{NaOH}_{(\mathrm{aq})} \longrightarrow \mathrm{Na}_{2} \mathrm{ZnO}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{t})}\)

(g) Dilute HCl was added to limestone.
Answer:

• When hydrochloric acid is added to limestone, carbon dioxide is liberated. Limestone is calcium carbonate.
  CaCO₃ + 2 HCl → CaCl₂ + CO₂ + H₂O
• Carbon dioxide is prepared in the laboratory using these chemicals.

(h) Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it.
Answer:

• On heating, the crystalline structure of blue vitriol breaks down to form a colourless powder and water is released.
• This water is part of the crystal structure of blue vitriol.
• It is called water of crystallization.
• On adding water to the white powder, a solution was formed which has the same colour as the copper sulphate salt solution.

(i) Dilute H₂SO₄ was taken in an electrolytic cell and electric current was passed through it.
Answer:

• If pure water is used in the electrolytic cell, current does not flow even on putting on the switch.
• Pure water is a bad conductor of electricity. Dilute H₂SO₄ is acidulated water.
• The electrical conductivity of water increases on mixing with strong acid or base in it due to their dissociation and electrolysis of water takes place.
• H₂SO₄ is fully dissociated in aqueous solution. \(\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow 2 \mathrm{H}^{+}+\mathrm{SO}_{4}^{2-}\)
• H₂O is a weak electrolyte and is only slightly dissociated \(\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{H}^{+}+\mathrm{OH}^{-}\)
• During electrolysis, the hydrogen ions migrate towards the cathode and are discharged there.

[H+ ions gains electrons and are converted to hydrogen gas]
\(2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}\)
Cathode reaction:
\(2 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{i})}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}+2 \mathrm{OH}_{(\mathrm{aq})}^{-}\)
Anode reaction:
\(2 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \longrightarrow \mathrm{O}_{2(\mathrm{~g})}+4 \mathrm{H}_{(\mathrm{aq})}^{+}+4 \mathrm{e}\)

• For every hydrogen ion discharged at the anode, another hydrogen ion is formed at the cathode.
• The net result is that the concentration of the sulphuric acid remains constant and electrolysis of water is overall reaction. \(2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{H}_{2}+\mathrm{O}_{2}\)
• The volume of the hydrogen gas formed near the cathode is double that of the oxygen gas formed near the anode.

3. Classify the following oxides into three types and name the types.
CaO, MgO, CO₂, SO₃, Na₂O, ZnO, Al₂O₃, Fe₂O₃
Answer:
There are three types of oxides : Basic oxides, Acidic oxides and Amphoteric oxides.

Generally metal oxides are basic in nature.
Exception : Al₂O₃ and ZnO are amphoteric oxides.
Generally non-metal oxides are acidic in nature.

4. Explain by drawing a figure of the electronic configuration.

a. Formation of sodium chloride from sodium and chlorine.
Answer:

b. Formation of a magnesium chloride from magnesium and chlorine.
Answer:

5. Show the dissociation of the following compounds on dissolving in water, with the help of chemical equation and write whether the proportion of dissociation is small or large.
Hydrochloric acid, Sodium chloride, Potassium hydroxide, Ammonia, Acetic acid, Magnesium chloride, Copper sulphate.
Answer:
(a) Hydrochloric acid (HCl)

• \(\mathrm{HCl}_{(g)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{(\mathrm{aq})}^{-}\)
• Hydrochloric acid is a strong acid, as on dissolving in water, it dissociates almost completely and the resulting aqueous solution contains mainly H ions and the concerned acidic radical.
• The proportion of dissociation is large.

(b) Sodium chloride (NaC1)

• \(\mathrm{NaCl}_{(s)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Na}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{\text {(aq) }}^{-}\)
• When an ionic compound begins to dissolve in water, the water molecules push themselves in between the positive and negative ions of the compound and separate them from each other.
• The proportion of dissociation is large.

(c) Potassium hydroxide (KOH)

• \(\mathrm{KOH}_{(n)} \frac{\text { Water }}{\text { dissociation }} \mathrm{K}_{(\mathrm{aq})}^{+}+\mathrm{OH}_{(\mathrm{aq})}\)
• Potassium hydroxide is a strong base, as on dissolving in water, it dissociates almost completely and the resulting aqueous solution contains mainly OH⁺ ions and the concerned basic radical.
• The proportion of dissociation is large.

(d) Ammonia (NH₃)
(i) \(\mathrm{NH}_{3(\mathrm{~g})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{n}}-\frac{\text { Water }}{\text { uissociation }}>\mathrm{NH}_{4 \text { (aq) }}^{+}+\mathrm{OH}_{\text {(aq) }}^{-}\)
(ii) Ammonia dissolves in water to form NH₄OH (ammonium hydroxide). NH₄OH does not dissociate completely as it is a weak base. The aqueous solution contains a small proportion of OH^– ions and the concerned basic radical along with a large proportion of undissociated molecules of the base i.e. NH₄OH.
(iii) The proportion of dissociation is small.

(e) Acetic acid (CH₃COOH)

• \(\mathrm{CH}_{3} \mathrm{COOH}_{(l)} \frac{\text { Water }}{\text { dissociation }} \mathrm{CH}_{3} \mathrm{COO}_{(\text {aq) }}+\mathrm{H}_{(a z)}+{ }^{+}\)
• Acetic acid is a weak acid, on dissolving in water it does not dissociate completely, and the resulting aqueous solution contains H⁺ ion and the concerned acidic radical in small proportion along with large proportion of the undissociated molecules of the acid.
• The proportion of dissociation is small.

(f) Magnesium chloride (MgCl₂)

• \(\mathrm{MgCl}_{2(\mathrm{~s})} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Mg}^{2+} \text { (aq) }+2 \mathrm{Cl}^{-} \text {(aq) }\)
• Magnesium chloride dissolves in water and forms magnesium ions and chloride ions. When an ionic compound begins to dissolve in water, the water molecules push themselves in between the ions of the compound and separate them from each other.
• The proportion of dissociation is large.

(g) Copper sulphate (CuSO₄)

• \(\mathrm{CuSO}_{4(s)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Cu}_{(\mathrm{aq})}^{2+}+\mathrm{SO}_{4}^{2-}\)
• When Copper sulphate is dissolved in water it forms copper ions and sulphate ions. When an ionic compound begins to dissolve in water, water molecules push themselves in between the ions of the compound and separate them from each other.
• The proportion of dissociation is large.

6. Write down the concentration of each of the following solutions in g/L and mol/L.

a. 7.3g HCl in 100ml solution
b. 2g NaOH in 50ml solution
c. 3g CH₃COOH in 100ml solution
d. 4.9g H₂SO₄ in 200ml solution
Answer:
To find : The concentration in g/L.
Solution:

7. Obtain a sample of rainwater. Add to it a few drops of universal indicator. Meausre its pH. Describe the nature of the sample of rainwater and explain the effect if it has on the living world.
Answer:

• pH of rain water is 6.5 that means rain water is slightly acidic.
• When we add universal indicator to rain water it turns orangish red, indicating pH value is between 0 to 7, which tells us that rain water is acidic in nature.
• Most of the plants grow best when pH of soil is close to 7. If the soil is too acidic or too basic, it affects plant growth.

8. Answer the following questions.

a. Classify the acids according to their basicity and give one example of each type.
Answer:

• Basicity of acids : The number of H⁺ ions obtainable by the dissociation of one molecule of an acid is called its basicity. The acids are classified as monobasic, dibasic and tribasic acids based on the number of H⁺ ions present.
• Examples of monobasic acid : HCl, HNO₃, CH₃COOH
• Examples of dibasic acid: H₂SO₄, H₂CO₃
• Examples of tribasic acid: H₃BO₃, H₃PO₄

b. What is meant by neutralization? Give two examples from everyday life of the neutralization reaction.
Answer:

• In neutralization reaction, an acid reacts with a base to form salt and water.
• In a neutralisation reaction the acid dissociates to form H⁺ ions and base dissociates to form OH ions.
• They combine to form H₂O molecules which mixes with the solvent.

Examples in daily life:

• When people suffer from acidity, they take some antacids to neutralise the acid in their stomach.
• If an ant stings us the pain is due to formic acid. It is neutralised by rubbing moist baking soda which is basic in nature.

c. Explain what is meant by electrolysis of water. Write the electrode reactions and explain them.
Answer:
Electrolysis of water:

• Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to an electric current being passed through acidified water.
• Cathode reaction:
  \(2 \mathrm{H}_{2} \mathrm{O}_{(l)}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}+2 \mathrm{OH}_{(\mathrm{aq}}\)
• Anode reaction:
  \(2 \mathrm{H}_{2} \mathrm{O}_{(l)} \longrightarrow \mathrm{O}_{2(\mathrm{~g})}+4 \mathrm{H}_{(\mathrm{aq})}^{+}+4 \mathrm{e}^{-}\)
• It is found that the volume of gas formed near the cathode is double that of the gas formed near the anode.
• Hydrogen gas is formed near the cathode and oxygen gas near the anode.
• From this, it is clear that electrolysis of water has taken place and its constituent element have been released.

9. Give a reason for the following.

a. Hydronium ions are always in the form H₃O⁺.
Answer:

• Acids in water gives H⁺ ions. These H⁺ ions do not exist freely in water.
• This is because H⁺ is a single proton, a hydrogen atom has only one proton and one electron.
• If the electron is removed to make H⁺, all that is left is an extremely tiny positively charged nucleus.
• This H ion will immediately combine with the surrounding water (H₂O) molecules to form (H₃O₄) hydronium ion.

b. Buttermilk spoils if kept in a copper or brass container.
Answer:

• Buttermilk contains an organic acid called as lactic acid.
• The lactic acid reacts with copper and brass and forms toxic compounds which are not fit for consumption.
• They are harmful and may cause food poisoning.
• So it is not advisable to keep buttermilk in brass or copper containers.

10. Write the chemical equations for the following activities.

(a) NaOH solution was added to HCl solution.
Answer:
When NaOH reacts with HCl, it gives NaCl and water.

(b) Zinc dust was added to dilute H₂SO₄.
Answer:
When zinc reacts with dilute sulphuric acid, it forms zinc sulphate and hydrogen gas is liberted.

(c) Dilute nitric acid was added to calcium oxide.
Answer:
When dilute nitric acid reacts with calcium oxide, it forms calcium nitrate and water.

(e) Carbon dioxide gas was passed through KOH solution.

(f) Dilute HCl was poured on baking soda.

11. State the differences.

a. Acids and bases
Answer:

b. Cation and anion
Answer:

c. the Negative electrode and the positive electrode.

Answer:

12. Classify aqueous solutions of the following substances according to their pH into three groups : 7, more than 7, less than 7.

Common salt, sodium acetate, hydrochloric acid, carbon dioxide, potassium bromide, calcium hydroxide, ammonium chloride, vinegar, sodium carbonate, ammonia, sulphur dioxide.
Answer:

Class 9 Science Chapter 5 Acids, Bases and Salts Intext Questions and Answers

Question 1.
How are the following substances classified into three groups with the help of litmus?
Lemon, tamarind, baking soda, buttermilk, vinegar, orange, milk, lime, tomato, milk of magnesia, water, alum.
Answer:

Question 2.
Fill in the columns in the part of the following table:
Answer:

Question 3.
Complete the following table of the concentration of various aqueous solutions.
Answer:

Question 4.
Complete the following table of neutralization reactions and also write down the names of the acids, bases and salts in it.
Answer:

Question 5.
What are the names of the following compounds? NH₃, Na₂O, CaO.
Answer:
NH₃ : Ammonia
Na₂O : Sodium oxide
CaO : Calcium oxide

Question 6.
Into which type will you classify the above compounds, acid, base or salt?
Answer:
NH₃ : base
Na₂O : base
CaO : base

Question 7.
ive examples of monobasic, dibasic and tribasic acids.
Answer:
Monobasic acid examples: HNO₃, HCl, CH₃COOH
Dibasic acid examples: H₂SO₄, H₂CO₃
Tribasic acid examples: H₃BO₃, H₃PO₄

Question 8.
Give the three types of bases with their examples.
Answer:
Types of bases:
Monoacidic base examples : NaOH, KOH, NH₄OH
Diacidic base examples: Ca(OH)₂, Ba(OH)₂
Triacidic base examples: A(OH)₃, Fe(OH)₃

Question 9.
What are the colours of the following natural and synthetic indicators in acidic and basic solutions? Litmus, turmeric, jamun, methyl orange, phenolphthalein?
Answer:

Question 10.
On mixing the substances as shown here, what are the resulting mixtures formed by mixing the following substances called?
(a) Water and salt
(b) Water and sugar
(c) Water and sand
(d) Water and sawdust
Answer:
(a) Water and salt – Homogeneous mixture
(b) Water and sugar – Homogeneous mixture
(c) Water and sand – Heterogeneous mixture
(d) Water and sawdust – Heterogeneous mixture

Question 11.
What would be the definition of an acid and a base with reference to the neutralization reaction?
Answer:

• Acid: An acid is a substance which neutralises a base to form salt and water.
• Base: A base is a substance which neutralises an acid to form salt and water.

Answer the following questions:

Question 1.
Take aqueous solution of sodium chloride, copper sulphate, glucose, urea, dil.H₂SO₄ and dil.NaOH in a beaker and test the electrical conductivity of the solutions. Answer the given below questions.

(a) With which solutions did the bulb glow?
Answer:
Solutions with which bulb glows: Aqueous solution of NaCl, CuSO₄, H₂SO₄ and NaOH.

(b) Which solutions are electrical conductors?
Answer:
Solutions which are electrical conductors:
NaCl, CuSO₄, H₂SO₄ and NaOH.

Question 2.
During electrolysis of copper sulphate, if electric current is passed through the electrolytic cell for a long time, what change would be seen at the anode?
Answer:

• When electricity is passed for a long time through copper sulphate solution, the following reaction is seen at the anode: Anode Reaction: Cu(s) → Cu²⁺(aq) + 2e^–
• All the copper atoms will get converted into copper ions and get deposited on the cathode. This process continues till the copper anode exists.

Question 3.
Would water be a good conductor of electricity?
Answer:
Pure water is not a good conductor of electricity.

Answer the following questions:

Question 1.
(i) With which solutions did the bulb glow?
(ii) Which solutions are electrical conductors?

Answer:
(i) The bulbs glows when the wire are immersed in NaCl solution.
(ii)

Question 2.
What would be the definition of an acid and a base with reference to the neutralization reaction?
Answer:

• Acid: An acid is a substance which neutralises a base to form salt and water.
• Base: A base is a substance which neutralises an acid to form salt and water.

Question 3.
Dissolve 2g salt in 500ml pure water. Take 250 ml of this solution in a 500ml capacity beaker. Connect two electrical wires to the positive and negative terminals of a power supply. Remove the insulating cladding from about 2cm portions at the other ends of the wires. These are the two electrodes. Fill two test tubes upto the brim with the prepared dilute salt solution. Invert them on the electrodes without allowing any air to enter. Start the electric current under 6V potential difference from the power supply. Observe what happens in the test tubes after some time.
(a) Did you see the gas bubbles forming near the electrodes in the test tubes?
(b) Are these gases heavier or lighter than water?
(c) Are the volumes of the gases collected over the solution in the two test tubes the same or different?
(d) Test the solutions in the two test tubes with litmus paper, what do you see?
(e) Repeat the activity by using dilute H₂SO₄ as well as dilute NaOH as the electrolyte.
Answer:
(a) Yes, gas bubbles can be seen forming near the electrodes in the test tube.
(b) These gases are lighter than water.

(c) The volumes of gases collected over the solution in the two test tubes are different.
(d) The solution in the cathode turns red litmus blue while solution in anode turns blue litmus red.
(e) When the above experiment is repeated with dil H₂SO₄ and dil NaOH, Hydrogen gas is liberated at cathodes and oxygen gas is liberated at anode.

Answer the following questions:

Question 1.
Cut a lemon into two equal parts. Take the juice of each part into two separate beakers. Pour 10 ml of drinking water in one beaker and 20 ml in the second. Stir the solutions in both the beakers and taste them. Is there any difference in the tastes of the solutions in the two beakers? What is that difference?
Answer:

• In the above activity, the sour taste of the solutions is because of the solute, lemon juice in them.
• The quantity of the lemon juice is the same in both the solutions. Yet their tastes are different.
• The solution in the first beaker is more sour than the one in the second.
• Although the quantity of the solute is the same in both the solutions, the quantity of the solvent is different.
• Ratio of the quantity of the solute to the quantity of the resulting solution is different. This ratio is larger for the solution in the first beaker and therefore that solution tastes more sour.
• On the other hand, the proportion of the lemon juice in the total solution in the second beaker is smaller and taste is less sour.
• The taste of foodstuff depends upon the nature of the taste-giving ingredient and its proportions in the foodstuff.
• Similarly, all the properties of a solution depend on the nature of the solute and solvent and also on the proportion of the solute in a solution
• The proportions of a solute in a solution is called the concentration of the solute in the solution.

Question 2.
Take a big test tube. Choose a rubber stopper in which a gas tube can be fitted. Take a few pieces of magnesium ribbon in the test tube and add some dilute HCl to it. Take a lighted candle near the end of the gas tube and observe. What did you observe?

Answer:

• Magnesium metal reacts with dilute HCl and an inflammable gas, hydrogen, is formed.
• During this reaction, the reactive metal displaces hydrogen from the acid to release hydrogen gas.
• At the same time, the metal is converted into basic radical which combines with the acidic radical from the acid to form the salt.
  \(\mathrm{Mg}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq}) \longrightarrow} \underset{\rightarrow}{\mathrm{MgCl}_{2(\mathrm{aq})}}+\mathrm{H}_{2(\mathrm{~g})}\)

Question 3.
Take some water in a test tube and add a little red oxide (the primer used before painting iron articles) to it. Now add a small quantity of dilute HCl to it, shake the test tube and observe.
(a) Does the red oxide dissolve in water?
(b) What change takes place in the particles of red oxide on adding dilute HCl?
Answer:
(a) The chemical formula of red oxide is Fe₂O₃. It is insoluble in water.
(b) The water-insoluble red oxide reacts with HCl to produce a water-soluble salt FeCl₃.

• This gives a yellowish colour to the water.
• The following chemical equation can be written for this chemical change.
  \(\mathrm{Fe}_{2} \mathrm{O}_{3(\mathrm{~s})}+6 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow 2 \mathrm{FeCl}_{3(\mathrm{aq})}+3 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)

Question 4.
Fit a bent tube in a rubber cork. Take some lime water in a test tube and keep it handy. Take some baking soda in another test tube and add some lemon juice to it. Immediately fit the bent tube over it. Insert its other end into the lime water. Note down your observations of both the test tubes. Repeat the procedure using washing soda, vinegar and dilute HC1 properly. What do you see?
Answer:

• In this activity, when limewater comes in contact with the gas released in the form of an effervescence, it turns milky.
• This is a chemical test for carbon dioxide gas.
• When lime water turns milky, we infer that the effervescence is of CO₂.
• This gas is produced on the reaction of acids with carbonate and bicarbonate salts of metals.
• A precipitate of CaCO₃ is produced on its reaction with the lime water Ca(OH)₂.
• This reaction can be represented by the following chemical equation.
  \(\mathrm{Ca}(\mathrm{OH})_{2(\mathrm{aq})}+\mathrm{CO}_{2(\mathrm{~g})} \longrightarrow \mathrm{CaCO}_{3(\mathrm{~s})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)
• Washing soda is sodium carbonate Na2CO₃. It will react same as baking soda (NaHCO₃).
• Vinegar and HCl are acids, they do not react chemically with lemon juice.

Class 9 Science Chapter 5 Acids, Bases and Salts Additional Important Questions and Answers

Select the correct option

Question 1.
…………………. acid is present in lemon.
(a) malic acid
(b) tartaric acid
(c) citric acid
(d) butyric acid
Answer:
(c) Citric acid

Question 2.
Tamarind contains …………………. acid.
(a) Lactic acid
(b) tartaric acid
(c) matlic acid
(d) butyric acid
Answer:
(b) tartaric

Question 3.
Butter milk contains …………………. acid.
(a) butyric acid
(b) Lactic acid
(c) matlic acid
(d) citric acid
Answer:
(a) Butyricacid

Question 4.
If the basic radical is H+ the type of compound is ………………… .
(a) neutral
(b) base
(c) acid
(d) alkali
Answer:
(c) Acid

Question 5.
The name of compound NH3 is ………………… .
(a) nitric acid
(b) ammonium
(c) nitride
(d) ammonia
Answer:
(b) ammonia

Question 6.
The bases which are soluble in water are called as ………………… .
(a) indicators
(b) acids
(c) alkalis
(d) salts
Answer:
(c) alkalis

Question 7.
H₃PO₄ is a …………………. acid.
(a) monobasic
(b) tribasic
(c) tetrabasic
(d) dibasic
Answer:
(b) tribasic

Question 8.
According to pH scale pure water has a pH of ………………… .
(a) 6
(b) 7
(c) 5
(d) 8
Answer:
(b) 7

Question 9.
With reference to neutralization, metallic oxides are ………………… in nature.
(a) basic
(b) neutral
(c) acidic
(d) saline
Answer:
(a) basic

Question 10.
Molecular formula of blue vitriol is ………………… .
(a) CuSO₃ 5H₂O
(b) CuSO₄ 4H₂O
(c) CUSO₃ 4H₂O
(d) CUSO₄ 5H₂O
Answer:
(d) CUSO₄ 5H₂O

Question 11.
Molecular formula of crystalline alum is ………………… .
(a) KSO₄, AISO₄, 24H₂O
(b) K₂SO₄, ALSO₄, 24H₂O
(c) K₂SO₄, AL₂(SO₄)₃, 24H₂O
(d) KSO₄, Al₂(SO₄)₃, 24H₂O
Answer:
(c) K₂SO₄, AL₂(SO₄)₃, 24H₂O

Question 12.
Molecular formula for sodium oxide is ………………… .
(a) Na₂O
(b) NaO₂
(c) NaO
(d) Na₂O₂
Answer:
(a) Na₂O

Question 13.
H₂CO₃ is …………………. acid.
(a) monobasic
(b) dibasic
(c) tribasic
(d) tetrabasic
Answer:
(b) dibasic

Question 14.
Molecular formula of Red oxide is ………………… .
(a) Fe₂O₃
(b) CuO
(c) Fe₃O₄
(d) Na₂O
Answer:
(a) Fe₂O₃

Question 15.
The positive terminal electrode is called as ………………… .
(a) anode
(b) cathode
(c) anion
(d) cation
Answer:
(a) anode

Question 16.
…………………. produced in stomach helps in digestion.
(a) Hydrochloric acid
(b) Oxalic acid
(c) Sulphuric acid
(d) Nitric acid?
Answer:
(a) Hydrochloric acid

Question 17.
The solution turns blue litmus red, its pH is likely to be ………………… .
(a) 7
(b) 4
(c) 14
(d) 9
Answer:
(b) 4

Question 18.
An ionic compound NaCl is formed by ………………… .
(a) Na⁺ and Cl^–
(b) Na⁺ and Cl⁺
(c) Na^– and Cl^–
(d) Na^– and Cl⁺
Answer:
(a) Na⁺ and Cl^–

Question 19.
pH of strong acid is ………………… .
(a) 0
(b) 7
(c) 8
(d) 14
Answer:
(a) 0

Question 20.
HCl + NaOH → NaCl + H₂O is a …………………. reaction.
(a) neutralization
(b) crystallisation
(c) electrolysis
(d) dissociation
Answer:
(a) neutralization

Question 21.
Adding water to acid is an …………………. reaction.
(a) endothermic
(b) exothermic
(c) neutralisation
(d) crystallisation
Answer:
(b) exothermic

Find the odd one out:

(a) Rose Petal, Turmeric, Phenolphthalein, Indigo.
Answer:
Phenolphthalein is odd one out as rest are natural indicators while phenolphthalein is a synthetic indicator.

(b) Lime water, Vinegar, Acetic acid, Tartaric acid.
Answer:
Lime water is odd one out as this is basic in nature while rest are acidic.

(c) NaHCO₃, HCl, H₂SO₄, HNO₃
Answer:
NaHCO₃ is odd one out as it is base while rest are acids.

(d) Oxalic acid, Nitric acid, Citric acid, acetic acid.
Answer:
Nitric acid is odd one out as others are weak acids while Nitric acid is a strong acid.

(e) Crystalline, Liquid, Gases, Solid.
Answer:
Crystalline is odd one out as this is nature of a compound while others are physical states of compounds.

(f) Ca(OH)₂, Mg (OH)₂, NaOH, NH₄OH.
Answer:
NaOH is odd one out even though all are bases but NaOH is highly soluble in water compared to others.

Name the following:

Question 1.
Name the three types of ionic compounds.
Answer:
The three types of ionic compounds are acids, bases and salts.

Question 2.
Name the two constituents of molecule of an ionic compound.
Answer:

• Cation (positive ion/ basic radical)
• Anion (negative ion/acidic radical).

Question 3.
Name any three acids with their molecular formula.
Answer:

• Hydrochloric acid – HC1
• Sulphuric acid – H₂SO₄
• Nitric acid – HNO₃

Question 4.
Name any three bases with their molecular formula.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH
• Calcium hydroxide – Ca(OH)₂

Question 5.
Name any three salts with their molecular formula.
Answer:

• Sodium chloride – NaCl
• Potassium sulphate – K₂ SO₄
• Calcium chloride – CaCl₂

Question 6.
Name any two strong acids.
Answer:

• Hydrochloric acid – HC1
• Sulphuric acid – H₂ SO₄

Question 7.
Name any two weak acids.
Answer:

• Acetic acid – CH₃ COOH
• Carbonic acid – H₂ CO₃

Question 8.
Name any two strong bases.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 9.
Name a weak base.
Answer:
Ammonium hydroxide – NH₄OH

Question 10.
Name any two alkalis.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 11.
Name any two acids with their basicity 1 (monobasic)
Answer:

• Hydrochloric acid – HC1
• Nitric acid – HNO₃

Question 12.
Name any two acids with their basicity 2 (dibasic)
Answer:

• Sulphuric acid – H₂ SO₄
• Carbonic acid – H₂CO₃

Question 13.
Name any two acids with their basicity 3 (tribasic)
Answer:

• Boric acid – H₃BO₃
• Phosphoric acid – H₃PO₄

Question 14.
Name any two bases with their acidity 1 (monoacidic)
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 15.
Name any two bases with their acidity 2 (diacidic)
Answer:

• Calcium hydroxide – Ca(OH)₂
• Barium hydroxide – Ba(OH)₂

Question 16.
Name any two bases with their acidity 3 (triacidic)
Answer:

• Aluminium hydroxide – Al(OH)₃
• Ferric hydroxide – Fe(OH)₃

Question 17.
Name the two units to express the concentration of the solution.
Answer:

• mass of solute in grams dissolved in one litre of the solution grams per litre, (g/L).
• Number of moles of the solute dissolved in one litre of the solution. Molarity (M) of the solution.

Match the columns:

Question 1.

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 2.

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 3.

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 4.

Answer:
(1 – b),
(2 – c),
(3 – d),
(4 – a)

Question 5.

Answer:
(1-c),
(2- a),
(3 – d),
(4 – b)

State whether the following statements are true or false and if false. Correct the false statement:

(1) The separation of H and CI in HCI is in absence of water.
(2) \(\mathrm{NaOH}_{(\mathrm{s})} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Na}_{(\mathrm{aq})}^{+}+\mathrm{OH}_{(\mathrm{aq})}^{-}\)
(3) H₂SO₄ is a strong acid.
(4) NaC1 is an ionic compound.
(5) Turmeric is synthetic indicator.
(6) Metal + Dilute acid forms salt and water.
(7) Copper oxide is called red primer.
(8) Oxide of non-metal + Acid → Salt + Water.
(9) Zinc oxide reacts with sodium hydroxide to form sodium zincate.
(10) Al₂O₃ is an amphoteric oxide.
(11) Blue vitriol ZnSO₄. 7H₂O.
(12) Molecular formula for crystalline Ferrous sulphate is Fe5O₄. 5H₂O.
(13) NaCl in water does not conduct electricity.
(14) Phenolphthalein is colourless in base.
Answer:
(1) False. The separation of H⁺ and Cl^– in HC1 is in presence of water.
(2) True
(3) True
(4) True
(5) False. Turmeric is a natural indicator.
(6) False. Metal + Dilute acid forms salt and hydrogen gas.
(7) False. Iron oxide is called red primer.
(8) False. Oxide of izan-metal + Base → Salt + Wafer.
(9) True
(10) True
(11) False. Blue Vitriol is CuSO₄. 5H₂O.
(12) False. Molecular formula for crystalline Ferrous sulphate is FeSO₄. 7H₂O.
(13) False. NaCl in water conducts electricity.
(14) False, Phenolphthalein is colourless in acid and pink in base.

Define the following:

Question 1.
Acid
Answer:
An acid is a substance which on dissolving in water gives rise to H ion as the only cation. For example, HC1, H₂ SO₄, H₂CO₃.

Question 2.
Base
Answer:
A base is a substance which on dissolving in water gives rise to the OW ion as the only anion. For, NaOH, Ca(OH)₂

Question 3.
Strong Acid
Answer:
On dissolving in water, a strong acid dissociates almost completely, and the resulting aqueous solution contains mainly H ions and the concerned acidic radical. e.g. HC1, HBr, HNO₃, H₂SO₄.

Question 4.
Weak Acid
Answer:
On dissolving in water a weak acid does not dissociate completely, and the resulting aqueous solution contains H+ ion and the concerned acidic radical in small proportion along with large proportion of the undissociated molecules of the acid, e.g., H₂CO₃ (Carbonic acid), CH₃COOH (Acetic acid)

Question 5.
Strong Base
Answer:
On dissolving in water, a strong base dissociates almost completely and the resulting aqueous solution contains mainly OH ions and the concerned basic radicals, e.g. NaOH, KOH, Ca(OH)₂, Na₂O.

Question 6.
Weak Base
Answer:
On dissolving in water, a weak base does not dissociate completely and the resulting aqueous solution contains a small proportion of OH ions and the concerned basic radical along with a large proportion of undissociated molecules of the base. e.g. NH₄ OH.

Question 7.
Alkali
Answer:
The bases which are highly soluble in water are called alkali, e.g. NaOH, KOH, NH3. Here, NaOH and KOH are strong alkalis while NH₃ is a weak alkali.

Question 8.
Basicity of acids
Answer:
The number of H⁺ ions obtainable by the dissociation of one molecule of an acid is called its basicity.

Question 9.
Acidity of bases
Answer:
The number of OH ions obtainable by the dissociation of one molecule of a base is called its acidity.

Question 10.
Concentration of solute in the solution.
Answer:
The proportion of a solute in a solution is called the concentration of the solute in the solution.

Question 11.
Concentrated solution.
Answer:
When the concentration of a solute in its solution is high, it is a concentrated solution.

Question 12.
Dilute solution
Answer:
When the concentration of a solute in its solution is low, it is a dilute solution.

Question 13.
Neutralization
Answer:
A reaction in which an acid reacts with a base to form salt and water is called a neutalization reaction.
NaOH + HC1 → NaCl + H₂O
Base + Acid → Salt + Water

Question 14.
Cathode
Answer:
The electrode connected to the negative terminal of a battery by means of a conducting wire is called a cathode.

Question 15.
Anode
Answer:
The electrode connected to the positive terminal of a battery by means of a conducting wire is called an anode.

Question 16.
Cations
Answer:
Cations are positively charged ions which are attracted towards negative electrode (cathode) when electricity is passed into a solution of an ionic compound.

Question 17.
Anions
Answer:
Anions are negatively charged ions which are attracted towards the positive electrode (anode) when electricity is passed into a solution of an ionic compound.

Question 18.
Electrolytic cell
Answer:
An assembly that consists of a container with an electrolyte and the electrodes dipped in it, is called an electrolytic cell.

Question 19.
Molarity of a solution
Answer:
The number of moles of the solute dissolved in one litre of the solution is called the molarity of that solution. The molarity of a solute is indicated by writing its molecular formula inside a square bracket for example [NaCl] = 1

Question 20.
Acid – base indicators
Answer:
Some natural and synthetic dyes show two different colours in acidic and basic solution, and such dyes are acid base indicators.

Explain the following chemical reactions with the help of balanced equations:

Question 1.
Magnesium reacts with dilute hydrochloric acid.
Answer:
When magnesium reacts with dilute hydrochloric acid, it forms magnesium chloride and hydrogen gas is liberated.

Question 2.
When copper reacts with nitric acid.
Answer:
When copper reacts with nitric acid, it forms copper nitrate and hydrogen gas is liberated.

Question 3.
When ferric oxide reacts with diluted hydrochloric acid.
Answer:
When Ferric oxide reacts with diluted hydrochloric acid, it forms ferric chloride and water.

Question 4.
When calcium oxide reacts with dilute hydrochloric acid.
Answer:
When calcium oxide reacts with dilute hydrochloric acid, it forms calcium chloride and water.

Question 5.
When Magnesium oxide reacts with dilute hydrochloric acid.
Answer:
When magnesium oxide reacts with dilute hydrochloric acid, it forms magnesium chloride and water.

Question 6.
When zinc oxide reacts with dilute hydrochloric acid.
Answer:
When zinc oxide reacts with dilute hydrochloric acid, it forms zinc chloride and water.

Question 7.
When aluminium oxide reacts with hydrogen fluoride
Answer:
When aluminium oxide reacts with hydrogen fluoride, it forms Aluminium fluoride arid water.

Question 8.
When carbon dioxide reacts with sodium hydroxide.
Answer:
When carbon dioxide reacts with Sodium hydroxide, it forms Sodium carbonate and water.

Question 9.
When carbon dioxide reacts with potassium hydroxide.
Answer:
When carbon dioxide reacts with potassium hydroxide, it forms potassium carbonate and water.

Question 10.
When sulphur trioxide reacts with sodium hydroxide.
Answer:
When sulphur trioxide reacts with sodium hydroxide, it forms sodium sulphate and water.

Question 11.
When calcium hydroxide reacts with carbon dioxide.
Answer:
When calcium hydroxide reacts with carbon dioxide, it forms calcium carbonate and water.

Question 12.
When sodium carbonate reacts with hydrochloric acid.
Answer:
When sodium carbonate reacts with hydrochloric acid, it forms sodium chloride, carbon dioxide and water.

Question 13.
When sodium carbonate reacts with sulphuric acid.
Answer:
When sodium carbonate reacts with sulphuric acid, it forms sodium sulphate, carbon dioxide and water.

Question 14.
When calcium carbonate reacts with nitric acid.
Answer:
When calcium carbonate reacts with nitric acid, it forms calcium nitrate, carbon dioxide and water.

Question 15.
When potassium carbonate reacts with sulphuric acid.
Answer:
When potassium carbonate reacts with sulphuric acid, it forms potassium sulphate, carbon dioxide and water.

Question 16.
When sodium bicarbonate reacts with hydrochloric acid. OR Dilute HC1 was poured on baking soda
Answer:
When sodium bicarbonate reacts with hydrochloric acid, it forms sodium chloride, carbon dioxide and water.

Question 17.
When potassium bicarbonate reacts with nitric acid.
Answer:
When potassium bicarbonate reacts with nitric acid, it forms potassium nitrate, carbon dioxide and water.

Question 18.
When sodium bicarbonate reacts with acetic acid.
Answer:
When sodium bicarbonate reacts with acetic acid, it forms sodium acetate, carbon dioxide and water.

Question 19.
When copper sulphate is heated.
Answer:
When copper sulphate is heated it loses it’s water of crystallization to form white anhydrous copper sulphate.

Question 20.
When Ferrous sulphate is heated.
Answer:
When ferrous sulphate is heated it loses its water of crystallization to form white anhydrous ferrous sulphate.

Q.2. (B)-3. Complete the following table.

Question 1.
Complete the following table.
Answer:

Complete the following reactions.

Question 1.
Answer:

Question 2.
Metal + Dilute acid → Salt + Hydrogen
Answer:

Question 3.
Metal oxide + Dilute acid → SaIt + Water
Answer:

Question 4.
Oxide of non-metal + base → salt + water
Answer:

Question 5.
Carbonate salt of metal + dilute acid → Another salt of metal + Carbon dioxide + water
Answer:

Question 6.
Bicarbonate salt of metal + dilute acid → Another salt of metal + carbon dioxide + water
Answer:

Give scientific reasons:

Question 1.
Ionic compound NaCl has very high stability.
Answer:

• The outermost shell of both Na⁺ and Cl^– ions is a complete octet.
• An electronic configuration with a complete octet indicates a stable state.
• A molecule of NaCl has Na⁺ and Cl^– ions. An ionic bond is formed between these ions.
• The force of attraction between them is very strong as it is formed between the oppositely charged Na⁺ and Cl^– ions.
• Therefore NaCl, an ionic compound has very high stability.

Question 2.
Ionic compound dissociates while forming an aqueous solution.
Answer:

• On dissolving in water, an ionic compound forms an aqueous solution.
• In the solid state, the oppositely charged ions in the ionic compound are sitting side by side.
• When an ionic compound being to dissolve in water, the water molecules push themselves in between the ions of the compound and it separates them from each other, that is to say, an ionic compound dissociates while forming an aqueous solution.

Question 3.
Blue coloured copper sulphate crystals become colourless on heating.
Answer:

• Copper sulphate crystals are blue in colour and crystalline in form due to presence of water of crystallisation.
• Each molecule of crystalline copper sulphate contains five molecules of water of crystallisation (CuSO₄.5H₂O).
• On heating, the copper sulphate crystals lose the water of crystallisation and turns into white amorphous powder called as anhydrous copper sulphate.
• Therefore, blue coloured copper sulphate crystals become colourless on heating.

Question 4.
During electrolysis of water, a few drops of sulphuric acid are added to it.
Answer:

• Pure water is a covalent compound and hence it is a non-electrolyte and does not conduct electricity.
• When a few drops of sulphuric acid (H₂SO₄) are added to water.
• Being a strong acid it dissociates almost completely in its solution forming H⁺ cations and \(\mathrm{SO}_{4}^{2-}\) anions.
• The movement of these ions in the solution towards the respective electrodes amount to the conduction of electricity through the solution.
• Therefore, during electrolysis of water, a few drops of sulphuric acid are added to it.

Question 5.
Glucose is a non-electrolyte.
Answer:

• Glucose is a covalent compound
• It does not form any ions in its aqueous solution.
• Due to this aqueous solution of glucose does not conduct electronic current.
• Hence, glucose is a non-electrolyte.

Question 6.
Pure water is a poor conductor of electricity but aqueous solution of sodium chloride conducts electricity.
Answer:

• Pure water does not contain any free ions.
• Sodium chloride (NaCl) is an ionic compound made up of sodium cation (Na⁺) and chloride anion (Cl)
• When sodium chloride is dissolved in water , these ions dissociates in its aqueous solution. ‘
• These ions are free to move in the solution and conduct electricity.
• Therefore, pure water is a poor conductor of electricity but aqueous solution of sodium Chloride conducts electricity.

Question 7.
When carbon dioxide gas is passed through freshly prepared lime water, the limewater turns milky.
Answer:

• Limewater traditionally means a weak solution of the alkali calcium hydroxide Ca(OH)₂.
• When CO₂ is passed through limewater, it reacts with calcium hydroxide to form insoluble particulates (precipitate of calcium carbonate (CaCO₃).
• Calcium carbonate is weak basic salt and this gives a milky white precipitate.
  
• Hence, lime water turns milky when CO₂ gas is passed through it.

Q.3.1. Answer the following:

Question 1.
Write down chemical equations for
(a) Zinc oxide reacts with sodium hydroxide
(b) Aluminium oxide reacts with sodium hydroxide.
Answer:
(a) When zinc oxide reacts with sodium hydroxide, it forms sodium zincate and water

(b) When Aluminium oxide reacts with sodium hydroxide, it forms sodium aluminate and water.

Question 2.
Can we call Al₂O₃ and ZnO acidic oxides on the basis of above reactions.
Answer:

• No, because they also react with acids to form their respective salts and water.
• So, they show the properties of basic oxides also.

Question 3.
Define ‘amphoteric oxides’ and give two examples.
Answer:

• Amphoteric oxides are those oxides which react with both adds as well as bases to form their respective salts and water.
• Amphoteric oxides show the properties of both acidic oxides as well as basic oxides. ZnO and Al₂ O₃ are amphoteric oxides.?

Question 4.
Take a solution of 1g copper sulphate in 50ml water in a 100 ml capacity beaker. Use a thick plate of copper as anode and a carbon rod as cathode. Arrange the apparatus as shown in the figure and pass an electric current through the circuit for some time. Do you see any changes?
Answer:

• A thin film of copper metal is deposited on cathode which is immersed in solution. There is no change in colour of solution
• The electrons from cathode combines with Cu²⁺ ion from the solution forming Cu atoms which were then deposited on the cathode.

Q.3.5. Answer in brief:

Question 1.
What are acids, bases and salts?
Answer:

• Compounds having H⁺ as the basic radical in their molecules are called Acids.
• Compounds having OH^– as the acidic radical in their molecule are called Bases.
• Ionic compounds which have a basic radical other than H⁺ and an acidic radical other than OH^– are called salts.

Question 2.
What is an ionic bond?
Answer:

• The molecule of an ionic compound has two constituents namely cation (positive ion / basic radical) and anion (negative ion / acidic radical).
• There is a force of attraction between these ions as they are oppositely charged, and that is called the ionic bond.
• The force of attraction between one positive charge on a cation and one negative charge on an anion makes one ionic bond.

Question 3.
Give examples to show that proportions of H⁺ and OH^– ions in aqueous solution determines the properties of those solutions.
Answer:
The examples to show that proportions of H⁺ and OH^– ions in aqueous solution determines the properties of those solutions are :

• The proportions of H⁺ and OH ions divides soil into the acidic, neutral and basic, types of soil.
• It is necessary for blood, cell sap etc to have H⁺ and OH^– ions in certain definite proportions for their proper functioning.
• Fermentation carried out with the help of micro-organisms, other biochemical processes and also many chemical processes require the proportion of H⁺ and OH^– ions to be maintained within certain limits.

Question 4.
What is pH scale?
Answer:

1. In 1909, the Danish scientist Sorensen introduced a convenient new scale of expressing H⁺ ion concentration which is found to be useful in chemical and biochemical processes.
2. It is the pH scale (pH: power of hydrogen). The pH scale extends from 0 to 14. According to this scale pure water has a pH of 7. pH 7 indicates a neutral solution. This pH is the midpoint of the scale.
3. The pH of an acidic solution is less than 7 and?

Question 5.
Give the pH of following solutions.
Answer:

Question 6.
What is universal indicator? Which is the most accurate method of measuring the pH of a solution?
Answer:

• In the pH scale, the pH of solutions varies from 0 to 14 in accordance with the strength of the acid or base.
• To show these variations in pH, a universal indicator is used.
• A universal indicator shows different colours at different values of pH. A universal indicator is made by mixing several synthetic indicators in specific proportions.
• The pH of a solution can be determined by means of a universal indicator solution or the pH paper made from it.
• However, the most accurate method of measuring the pH of a solution is to use an electrical instrument called pH meter.
• In this method, pH is measured by dipping electrodes into the solution.

Answer in detail:

Question 1.
Explain the Arrhenius theory of acids and bases.
Answer:
The Swedish scientist Arrhenius put forth a theory of acids and bases in the year 1887. This theory gives definitions of acids and bases as follows:
Acid : An acid is a substance which on dissolving in water gives rise to H ion as the only cation. For example, HCl, H₂SO₄, H₂CO₃

Base: Abase is a substance which on dissolving in water gives rise to the OH ion as the only anion, For example, NaOH, Ca(OH)₂

Question 2.
Write a short note on Neutralization.
Answer:

• Take 10 ml of dilute HCl in a beaker, go on adding dilute NaOH drop by drop and record the pH.
• Stop adding the NaOH when the green colour appears on the pH paper, that is when the pH of solution becomes 7.
• Both HCl and NaOH dissociate in their aqueous solutions.
• Addition of NaOH to HCl solution is like adding a large concentration of OH ions to a large concentration of H⁺ ions.
• However water dissociates into H⁺ and OH ions to a very small extent.
• Therefore on mixing the excess OH^– ions combines with excess H⁺ ions and forms H₂O molecules which mix with solvent water.
• This change can be represented by the ionic equation shown as follows. H⁺ + Cl^– + Na⁺ + OH^– → Na⁺ + Cl^– + H₂O
• It can be observed that Na⁺ and CT ions are there on both the sides. Therefore the net ionic reaction is H⁺ + OH^– → H₂O
• As NaOH solution is added drop by drop to the HCl solution, the concentration of ff goes on decreasing due to combination with added OH ions, and that is how the pH goes on increasing.
• When enough NaOH is added to HCl, the resulting aqueous solution contains only Na⁺ and Cl^– ions, that is, NaCl, a salt, and the solvent water. The only source of H⁺ and OH^– ions in this solution is a dissociation of water.
• Therefore, this reaction is called the Neutralization reaction. The Neutralization reaction is also represented by the following simple equation.
  

Question 3.
Explain the water of Crystallization.
Answer:

• Take some crystals of blue vitriol (CuSO₄. 5H₂O) in a test tube. Heat the test tube on a low flame of a burner.
• It was observed that on heating, the crystalline structure of blue vitriol broke down to form a colourless powder and water came out.
• This water was part of the crystal structure of blue vitriol. It is called water of crystallization.
• On adding water to the white powder a solution
  
  was formed which had the same colour as the solution in the first test tube.
• From this we come to know that no chemical change has occurred in the crystals of blue vitriol due to heating.
• Losing water on heating blue vitriol, breaking down of the crystal structure, losing blue colour and regaining blue colour on adding water are all physical changes.
  
• Similarly, ferrous Sulphate crystals also contain 7 molecules of water of crystallization which are lost on heating.
• The reaction is represented as
  
• Ionic compounds are crystalline in nature. These crystals are formed as a result of definite arrangement of ions.
• In the crystals of some compounds, water molecules are also included in this arrangement.
• That is the water of crystallization. The water of crystallization is present in a definite proportion of the chemical formula of the compound.

Question 4.
Explain the conduction of electricity through solutions of ionic compounds
Answer:

1. Electrons conduct electricity through electrical wires, and ions conduct electricity through a liquid or a solution.
2. Electrons leave the battery at the negative terminal, complete the electric circuit and enter the battery at the positive terminal.
3. When there is a liquid or a solution in the circuit, two rods, wires or plates are immersed in it. These are called electrodes.
4. Electrodes are made of conducting solid. The electrode connected to negative terminal of a battery by means of a conducting wire is called a cathode and the electrode connected to the positive terminal of a battery is called anode.
5. We have seen that salts, strong acids and strong bases dissociates almost completely in their aqueous solutions.
6. Therefore the aqueous solutions of all these three contain large number of cations and anions.
7. A characteristic of liquid state is the mobility of its particles. Due to its mobility the positive charged ions of the solution are attracted to the negative electrode or cathode.
8. On the other hand, the negative charged ions of the solution are attracted to the positive electrode or anode.
9. The movement of ions in the solution towards the respective electrodes accounts to the conduction of electricity through the solution.
10. From this we can understand that those liquids or solutions which contain a large number of dissociated ions conduct electricity.
    

Balbharati Maharashtra State Board 9th Std Science Textbook Solutions

• Laws of Motion Class 9 Science Textbook Solutions
• Work and Energy Class 9 Science Textbook Solutions
• Current Electricity Class 9 Science Textbook Solutions
• Measurement of Matter Class 9 Science Textbook Solutions
• Acids, Bases and Salts Class 9 Science Textbook Solutions
• Classification of Plants Class 9 Science Textbook Solutions
• Energy Flow in an Ecosystem Class 9 Science Textbook Solutions
• Useful and Harmful Microbes Class 9 Science Textbook Solutions
• Environmental Management Class 9 Science Textbook Solutions

Std 9 Science Chapter 14 Substances in Common Use Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 14 Substances in Common Use Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 14 Substances in Common Use Question Answer Maharashtra Board

Class 9 Science Chapter 14 Substances in Common Use Textbook Questions and Answers

1. Fill in the blanks.

a. The number of molecules of water of crystallization in washing soda is …………….…. .
b. The chemical name of baking soda is …………….…. .
c. …………….…. is used in treatment of hyperthyroidism.
d. The chemical name of Teflon is …………….…. .
Answer:
a. 10
b. Sodium bicarbonate
c. Iodine -123
d. Polytetra fluoroethylene (C₂F₄)_n

2. Match the pairs

Answer:
(1 – c),
(2 – a),
(3 – d),
(4 – b)

3. Write answers to the following

a. What is meant by radioactivity?
Answer:

• Elements with a high atomic number such as uranium, thorium, radium have a property of spontaneously emitting invisible, highly penetrating and high energy radiation.
• This property is called radioactivity.
• A substance having this property is called a radioactive substance.

b. When is said to be the nucleus unstable?
Answer:

• It is the balance of protons and neutrons in a nucleus which determines whether a nucleus will be stable or unstable.
• Too many neutrons or protons upset this balance disrupting the binding energy from the strong nuclear forces making the nucleus unstable.

c. Which diseases are caused by artificial food colours?
Answer:
Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

d. Where in the industrial field is radioactivity used?
Answer:
Industrial field Radiography

• Internal cracks and voids in cast iron articles and iron solder can be detected with the help of gamma rays.
• For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera.
• This technique is used for detecting flaws in metal work.

Measurement of thickness, density and level

• It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness.
• In the manufacturing process, a radioactive substance is placed on one side and an instrument to measure radiation on the other.
• The radiation read by the measuring instrument varies with the thickness of the sheet.
• Material inside a packing can also be examined by the same technique.

Luminescent paint and radio luminescence:

• The radioactive substances radium, promethium, tritium with some phosphor are used to make certain objects visible in the dark, for example, the hands of a clock, and certain other objects.
• Krypton-85 is used in HID (High-Intensity Discharge) lamps while promethium – 147 is used in portable X-ray units as the source of beta rays.

Use in Ceramic articles:

• Luminous colours are used to decorate ceramic tiles, utensils, plates, etc.
• Earlier uranium oxide was used in these paints.

e. Write down properties of teflon.
Answer:
Properties of teflon :

• The atmosphere and chemical substances have no effect on Teflon.
• Neither water nor oil will stick to Teflon coated articles.
• High temperatures do not affect Teflon as its melting point is 327 °C.
• Teflon coated articles are easy to clean.

f. What type of colours will you use to celebrate ecofriendly Rang Panchami? Why?
Answer:

• We regularly use artificial colours on Rang Panchami.
• The red colour used on Rang Panchami is very dangerous. It contains a high proportion of mercury in it.
• This poses risks like blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores, etc.
• Therefore, it is necessary to use eco-friendly colours.
• We will prepare colours for Rang Panchami from natural resources such as beet root, flowers of flame of forest, spinach, flame tree (gulmohar) and protect your health by using these.

g. Why has the use of methods like Teflon coating become more common?
Answer:
The use of methods like Teflon coating became more common because of following properties of teflon:

• The atmosphere, rain water and chemical substances have no effect on Teflon.
• Neither water nor oil will stick to Teflon coated articles.
• High temperatures do not affect Teflon as its melting point is 327 °C.
• Teflon coated articles are easy to clean.
• Teflon is a poor conductor of electricity.

4. Give a scientific explanation

a. Bleaching powder has the odour of chlorine.
Answer:

• Bleaching powder undergoes slow decomposition due to the carbon dioxide in air and chlorine gas is released.
• Bleaching powder gets its property because of this release of chorine gas.
  

b. The hard water of a well becomes soft on adding washing soda to it.
Answer:

• The hard water from a well or a bore-well becomes soft on adding washing soda and we come to know this from the lather formed on it.
• The hardness of water is due to the presence of chlorides and sulphates of calcium and magnesium in it.
• Na₂CO₃ is added to it to soften such water and make it suitable for use.
• The reaction with Na₂CO₃ causes the formation of insoluble carbonate salts of magnesium and calcium.
  MgCl_2(aq) + Na₂CO_3(s) → MgCO_3(s) + 2 NaCl_(s)

c. Soap forms a precipitate in hard water.
Answer:

• When soap is mixed with hard water, calcium and magnesium salts of fatty acids are formed.
• These being water insoluble, they form a precipitate and that is why lather is not formed.

d. The particles of powder are given an electric charge while spraying them to form the powder coating.
Answer:

• Powder coating is a method of applying a layer harder than paint on the surface of an iron object to prevent rusting.
• In this method, a polymer resin, a pigment and some other ingredients are melt, mixed, cooled and ground into a uniform powder.
• This powder is sprayed on the polished metal surface by electrostatic spray deposition (ESD).
• In this method, the particles of the powder are given an electrostatic charge due to which a uniform layer of the powder sticks to the metal surface.
• Then the object is heated in the oven along with the coating.
• A chemical reaction occurs in the layer, resulting in the formation of long cross-linked polymeric chains.

e. The aluminium article is used as an anode in the anodising process.
Answer:

• A protective layer is formed naturally on the surface of aluminium metal by reaction with oxygen in air.
• In the anodizing process, this layer is made of the desired thickness. Anodizing is done by electrolysis.
• Dilute Sulphuric acid is taken in the electrolytic cell and the aluminium article is dipped in it as the anode.
• When an electric current is passed, hydrogen gas is released at the cathode and oxygen gas at the anode.
• A reaction with oxygen occurs and a layer of hydrated aluminium oxide is formed on the anode. Therefore, aluminium article is used as an anode in the anodizing process.

f. When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path.
Answer:
(i) When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path. This is because the radiation coming out from radioactive substance are of three types Alpha rays, Beta rays and Gamma rays.

(ii) The rays which get deviated slightly towards negatively charged plate are called alpha rays. They get deviated towards negatively charged plate because they are made of positively charged particles, called as alpha particles (He++).

(iii) The rays which get deviated substantially towards the positively charged plate are called beta rays. They get deviated towards a positively charged plate because they are made of negatively charged particles called as beta particles (e-).

(iv) The rays which do not deviate at all are called gamma rays. They are uncharged electromagnetic radiation. Hence, marks are found at three places on the photographic plate. (For diagram refer Fig. 14 .2 from Q. 4(3))

g. A certain type of ceramic tiles are fixed on the outer layer of a space shuttle.
Answer:
(i) Each shuttle is covered by more than 24,000 of the six- by six-inch advance ceramic tiles. This tiles withstand high temperatures without decomposing. They are brittle, water-resistant and electrical insulator. Most of the tiles are made of silica fibres, which are produced from high-grade sand (SiO₂).

(ii) Silica is an excellent insulator because it transports heat slowly. When the outer portion of a tile gets hot, the heat takes a long time to work its way down through the rest of the tile to the shuttle’s skin. The tiles keep the orbiter’s aluminium skin at 350 degrees or less.

(iii) The silica fibers are mixed with water and chemicals, and the mixture is poured into molds, which are zapped in microwave ovens at 2,350°C to fuse the silica fibres. Tiles are too brittle to attach to the orbiter directly.

(iv) The shuttle’s skin contracts slightly while in orbit, then expands during re-entry.

(v) In addition, the stresses of launch and re-entry cause the skin to flex and bend. Such motions could easily crack the tiles or shake them off. To keep them in place, workers glue the tiles to flexible felt-like pads, then glue the pads to the orbiter.

5. Write answers to the following

a. Write about artificial food colours, the substances used in them and their harmful effects.
Answer:
(a) Artificial food colour and substances in them.

• Food colours are mixed in most soft drinks and foodstuffs available in the market.
• These food colours are in the form of powders, gels and pastes.
• Food colours are used in domestic as well as commercial products.
• Certain colours and essences are added to ice cream, ice candies, sauce, fruit juices, cold drinks, pickles, jams and jelly.
• Food colours are often found to be added to packaged meat (chicken, mutton), chilli powder, turmeric, sweets and other similar substances so as to give them a good colour.
• Tetrazene, sunset yellow are artificial food colours used extensively.

(b) Harmful effects of artificial food colours

1. Food colours added to pickles, jam and sauce contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
2. Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

b. What is meant by water of crystallization? Give examples of salts with water of crystallization, and their uses.
Answer:
The exact number of water molecules which are chemically bonded to a molecule of a salt within a hydrated crystalline compound is called as water of crystallization are:

Some substances in our daily use which contain water of crystallization are:

• Alum (Potash alum – K₂SO₄.Al₂(SO₄)₃.24H₂O)
• Borax (Na₂B₄O₇.10H₂O)
• Epsom salt (Magnesium sulphate MgSO₄.7H₂O)
• Barium chloride (BaCl₂.2H₂O)
• Sodium sulphate (Glauber’s salt Na₂SO₄.10 H₂O)
• Blue vitriol (Copper Sulphate – CuSO₄.5H₂O)

Uses of these salts are as given below:
(i) Alum (Potash alum – K₂SO₄.Al₂(SO₄)₃.24H₂O)

• Alum is used in the process of water purification.
• Because of the property of coagulation, the solid impurities in water come together, become heavy and settle to the bottom. As a result, the impure water or muddy above becomes clear.
• Alum powder, found in the spice section of many grocery stores, may be used in pickling recipes as a preservative to maintain fruit and vegetable crispness.
• Alum is used as the acidic component of some commercial baking powders.
• Alum has been used as an after shave treatment.

(ii) Borax (Na₂B₄O₇.10H₂O)

• Borax today is used for many cleaning purposes.
• It is used to make homemade laundry detergent.
• It is added as a cleaning boost to any other detergent.
• It even keeps ants and other pests away.

(iii) Epsom salt (Magnesium sulphate MgSO₄.7H₂O)

• Epsom salt is used as a relaxing magnesium bath soak.
• To grow better vegetables – Add a tablespoon of Epsom salt to the soil below a vegetable plant to boost growth.

(iv) Barium chloride (BaCl₂.2H₂O)

• In industry, Barium chloride is mainly used in the purification of brine solution in caustic chlorine plants.
• It is also used in the manufacture of heat treatment salts.
• It is used in hardening of steel.
• It is used in the manufacture of pigments.

(v) Sodium sulphate (Glauber’s salt Na₂SO₄.10H₂O)

• In the laboratory, anhydrous Sodium sulphate is widely used as an inert drying agent, for removing traces of water from organic solutions.
• Glauber’s salt, the decahydrate, is used as a laxative.

(vi) Blue vitriol (Copper sulphate CuSO₄.5H₂O)

• Blue vitriol is used in the blood test for diagnosing anaemia.
• Slaked Time is used with blue vitriol in the Bordeaux mixture which is used as a fungicide on fruits like grapes and musk melon.

c. Write briefly about the three methods of electrolysis of sodium chloride.
Answer:

• When an electric current is passed through a saturated solution of sodium chloride (brine) it is electrolysed and hydrogen gas is released at the cathode while chlorine gas is released at the anode.
• This method is used for production of chlorine gas. In this method an important basic compound NaOH is formed in the cell.
• Chemical reaction
  2NaCl + 2H₂O → 2NaOH + Cl₂ ↑ + H₂↑
• When salt is heated to a high temperature (about 800 °C), it melts. This is called the fused state of the salt.

6. Write the uses.

a. Anodizing
b. Powder coating
c. Radioactive substances
d. Ceramic
Answer:
(a) Anodizing : Anodizing is done on aluminum cooking utensils like griddles and cookers.

(b) Powder coating : Powder coating is done on iron objects to prevent rusting. Also, on Plastic and Medium density fibre (MDF) board, to make them highly durable, hard and attractive.

(c) Radioactive substances:
(I) Industrial field:
(i) Industrial Radiography : Internal cracks and voids in cast iron articles and iron solder can be. detected with the help of gamma rays. For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera. This technique is used for detecting flaws in metal work.

(ii) Measurement of thickness, density and level: It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness. In the manufacturing process, a radioactive substance is placed on one side and an instrument to measure radiation on the other. The radiation read by the measuring instrument varies with the thickness of the sheet. Material inside a packing can also be examined by the same technique.

(iii) Luminescent paint and radioluminescence:
The radioactive substances radium, promethium, tritium with some phosphor are used to make certain objects visible in the dark, for example, the hands of a clock, and certain other objects. Krypton-85 is used in HID (High Intensity Discharge) lamps while promethium-147 is used in portable X-ray units as the source of beta rays.

Use in Ceramic articles – Luminous colours are used to decorate ceramic tiles, utensils, plates, etc. Earlier uranium oxide was used in these paints.

(II) Field of agriculture :

• The genes and chromosomes that give seeds properties like fast growth, higher productivity, etc. can be modified by means of radiation.
• The radioactive isotope cobalt-60 is used for food preservation.
• Onions, potatoes are irradiated with gamma rays from cobalt-60 to prevent their sprouting.
• Strontium-90 is used as a tracer in the research on various crops.

(III) Medical science:

• Polycythemia : The red blood cell count increases in the disease polycythemia. Phosphorus- 32 is used in its treatment.
• Bone cancer : Strontium-89, strontium-90, samarium-153 and radium-223 are used in the treatment of bone cancer.
• Hyperthyroidism : Enlargement of thyroid gland, weight loss in spite of appetite, insomnia are the symptoms of hyperthyroidism.
• It occurs due to overproduction of hormones by the thyroid gland. Iodine-123 is used in the treatment of hyperthyroidism.
• Tumour detection : Boron-10, iodine-131, cobalt-60 are used in treatment of brain tumour, while arsenic-74 is used in detection of small tumours in the body.

(d) Ceramic : Pots made by a potter, Mangalore roofing tiles, construction bricks, pottery, terracotta articles are some examples of common ceramic articles that we see around.

7. Write the harmful effects

a. Artificial dye
b. Artificial food colour
c. Radioactive substances
d. Deodorant
Answer:
(a) Artificial dye:

• Dyeing hair can have adverse effects like hair fall, damage to hair texture, burning of skin, adverse effect on eyes, etc.
• Lipstick contains a dye named carmine. It does not affect lips but causes stomach disorders.
• Excessive use of plants for making natural dyes results in deterioration of the environment.

(b) Artificial food colour:

• Food colours added to pickles, jams and sauces contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
• Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

(c) Radioactive substances :

• The central nervous system is affected by radioactive radiations.
• Hereditary defects are generated by bombardment of radiation on D.N.A in the body.
• Radioactive radiation can penetrate the skin, and causes diseases like skin cancer, leukemia.
• The radioactive pollutants created due to explosions enter the body through air and it is difficult to control them.
• The radioactive pollutants released in the sea enter the bodies of fishes and through them enter the human body.
• The radioactive paint on the watch can cause cancer.
• The radioactive isotopes strontium-90 can enter the body through plants, fruits, flowers, cereals, milk, etc. and cause diseases like bone cancer, leukemia.

(d) Deodorant:

• Aluminium – Zirconium compounds are the most harmful chemicals in the deodorant. Disorders like headache, asthma, respiratory disorders, heart disease are likely to occur without our knowledge.
• There is a possibility of various skin disorders and also skin cancer due to the aluminium chlorohydrates.

8. Write the chemical formula Bleaching powder, common salt, baking soda, washing soda
Answer:

9. Explain what you see in the following picture

Powder coating
Answer:

1. This picture shows powder coating of the given object. Powder coating is a method of applying a layer harder than paint on the surface of an iron object to prevent rusting.
2. In this method, a polymer resin, a pigment and some other ingredients are melt mixed, cooled and ground into a uniform powder.
3. This powder is sprayed on the polished metal surface by electrostatic spray deposition (ESD).
4. In this method, the particles of the powder are given an electrostatic charge due to which a uniform layer of the powder sticks to the metal surface.
5. Then the object is heated in the oven along with the coating.
6. A chemical reaction occurs in the layer, resulting in the formation of long cross-linked polymeric chains.
7. This powder coating is highly durable, hard and attractive. Powder coating can be done on plastic and medium density fibre (MDF) board in day to day use as well.

Class 9 Science Chapter 14 Substances in Common Use Intext Questions and Answers

Can you recall?

Question 1.
What are detergents?
Answer:

• Detergent is a water-soluble cleansing agent which combines with impurities and dirt to make them more soluble, and differs from soap in not forming a scum with the salts in hard water.
• Today, detergents are more likely to be a mixture of synthetic chemicals and additives cooked up in a huge chemical plant and, unlike traditional soap, they’re generally liquids rather than solids.
• Detergents are used in everything from hair shampoo and clothes, washing powder to shaving foam and stain removers.
• The most important ingredients in detergents are chemicals called surfactants – a word made from bits of the words surface-active agents.

Question 2.
What are the important substances that we use in day to day life? For what purposes do we use them?
Answer:
Some of the substances we use in our day to day life and the purpose of using them are as follows:

Toothpaste: for cleaning teeth and maintaining hygienic conditions of mouth.

Soap : for bathing and maintaining hygienic conditions of body.

Natural and artificial fibers : we wear them as clothes to protect our body and many other purposes.

Washing powder: for cleaning clothes. Vegetables, fruits and food grains : they provide us with necessary vitamins, minerals and carbohydrates required for proper functioning of body.

Water : very important for our survival and many other functions of day to day life.

Metals : for making buildings, bridges, roads, vehicles, trains, ships, airplanes, utensils etc.

Acids, bases and salts : used for various purposes, for example, Sodium chloride which is used as common salt, a very necessary ingredient of our daily food without which our food is tasteless.

Question 3.
How are the various substances in day to day use classified from the scientific point of view?
Answer:
The various substances in day to day use are classified from the scientific point of view as elements, compounds, mixtures, metals, non-metals, acids, bases and salts.

Question 4.
Which chemicals and apparatus will you use in the laboratory for making soap?
Answer:
For making soap in laboratory following chemicals and apparatus are used :
Chemicals : Vegetable oil (coconut oil, castor oil, soya bean oil etc.)
Sodium hydroxide (NaOH)
Salt (Sodium chloride NaCl)

Apparatus :
500 ml glass beaker
Burner
Flat glass tray
Knife

Soaps are essential to personal and public health. They safely remove germs, soils and other contaminants and help us to stay healthy and make our surroundings more pleasant. Soaps are made from fats and oils or their fatty acids.

Take about 20 ml of any vegetable oil (coconut oil, castor oil, soybean oil etc.) in a beaker. Put about 30 – 35 ml of NaOH in it and heat and stir the mixture till a paste is formed. Now add a little salt. Stir again and allow the mixture to cool in a flat glass tray, on cooling it solidifies. Take a knife and cut it in soap bars as per the size required.

Question 5.
What are salts?
Answer:

• Inorganic substances occur naturally in the form of salts rather than acids or bases.
• The ionic compounds which do not contain H+ and OH ions and contain only one kind of cation and anion are called simple salts.
• For example, Na₂SO₄, K₃PO₄, CaCl₂.
• The sea is said to be a rich source of salts. In fact, the sea is a rich source of several salts of various elements such as chlorine, sodium, magnesium, potassium, calcium, bromine.
• The important salts found in sea water are sodium chloride, magnesium chloride, magnesium sulphate, potassium chloride, calcium carbonate and magnesium bromide.

Answer the following questions:

Question 1.
How is it determined whether a substance is acidic, basic or neutral?
Answer:

• In the pH scale, the pH of solutions varies from 0 to 14 in accordance with the strength of the acids or base.
• The pH scale shows different colours at different values of pH. Colour from dark red to yellow or from pH value 0 to 6 indicates the substances are acidic.
• Colour from light blue to violet or from pH value 8 to 14 indicates the substances are basic.
• Green colour or pH value 7 indicates the substances are neutral.

Question 2.
A sweets shop looks attractive because of the colourful sweets displayed there. Which colours are used in these substances?
Answer:

• Food colours and essences are used in sweets to make them colourful and tasty.
• These food colour are in the form of powders, gels and pastes.
• Food colours are natural as well as artificial.
• The food colours prepared from seeds, beetroot, flowers and fruit concentrate are natural.
• Tetrazene, sunset yellow are artificial food colours used extensively.

Question 3.
Make a list of substances in day to day use in accordance with their pH value (O to 14).
Answer:

Question 4.
A doctor gives you medicines when you fall ill. What are the medicines made from?
Answer:

• Long before pure chemicals were manufactured in labs, people used plants for medicine.
• There are over a hundred active ingredients derived from plants for use as drugs and medicines.
• The emergence of synthetic chemistry in the 1800s opened up new avenues for scientific research into drugs.
• Many chemists tried to locate medically active ingredients in plants (for instance the important malaria remedy quinine), and subsequently tried to make those substances in the laboratory in order to become independent of plant supplies.
• At the same time, a new industry developed as scientists developed processes to synthesise new chemicals on a large scale.
• New production methods developed in the late 1800s and early 1900s made it easier to standardise, package and transport medicines.

Question 5.
What problems do you get after playing colours on Rang Panchami? Why?
Answer:

• After playing colours on Rang Panchami we may get problems such as risks of blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores etc.
• This is because the colours used in rang panchami specially the red colour is very dangerous.
• It contains a high proportion of mercury in it.

Question 6.
Which colours will you use to prevent the occurrence of these problems?
Answer:

• To prevent the occurrence of these problem, instead of using artificial colours, natural colours should be used.
• Natural colours are prepared from natural resouroes such as beet root, flowers of flame of forest, spinach, flame tree (gulmohar).

Question 7.
What problem do you have on painting the house and furniture?
Answer:

• On painting the house and furniture with artificial colours which are dangerous, we may get problems such as risks of blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores, etc.
• This is because the colours contain a high proportion of mercury in it.

Question 8.
What is the property of Teflon because of which it is used in non-stickware?
Answer:
Following are the properties of teflon because of which it is used in nonstick cookware.

• The atmosphere and chemical substances have no effect on Teflon.
• Neither water nor oil will stick to Teflon coated non-stickware.
• High temperatures do not affect Teflon as its melting point is 327 °C.
• Teflon coated non-stickware are easy to clean.

Answer the following questions:

Question 1.
What is the strip shown below? What is it used for?
Answer:
The strip shown is pH metre scale. It is used to determined pH of solutions.

Question 2.
Prepare saturated solutions of given salts and put 2-3 drops of the universal indicator in them and note your observations in the table below:
Answer:

Class 9 Science Chapter 14 Substances in Common Use Additional Important Questions and Answers

Select the correct option:

Question 1.
Baking soda is ………………………… .
(a) non-metallic
(b) metallic
(c) acidic
(d) basic
Answer:
(d) basic

Question 2.
During electrolysis of NaCl in the fused state ………………………… is formed at cathode.
(a) sodium
(b) oxygen
(c) oxalic acid
(d) butyric acid
Answer:
(a) sodium

Question 3.
………………………… is known as chloride of lime.
(a) Calcium carbonate
(b) Sodium bicarbonate
(c) Sodium chloride
(d) Bleaching powder
Answer:
(d) Bleaching powder

Question 4.
Salt obtained from certain type of rock is called ………………………… .
(a) hard salt
(b) rock salt
(c) stone salt
(d) pure salt
Answer:
(b) rock salt

Question 5.
The ………………………… % aqueous solution of salt is called brine.
(a) 25
(b) 60
(c) 30
(d) 50
Answer:
(a) 25

Question 6.
The molecular formula for baking soda is ………………………… .
(a) Na₂CO₃
(b) NaHCO₃
(c) Na₂SO₄
(d) NaNO₃
Answer:
(b) NaHCO₃

Question 7.
Bleaching powder is also called ………………………… .
(a) Calcium oxygen chlorine
(b) Calcium oxychloride
(c) Calcium hydroxide
(d) Calcium oxalate
Answer:
(b) Calcium oxychloride

Question 8.
NaHCO₃ is also called as ………………………… .
(a) Sodium carbonate
(b) Sodium bicarbonate
(c) Sodium carbon oxide
(d) Sodium chloride
Answer:
(b) sodium bicarbonate

Question 9.
Molecular formula for Magnesium bromide is ………………………… .
(a) MgBr
(b) Mg₂Br
(c) Mg₂Br₂
(d) MgBr₂
Answer:
(d) MgBr₂

Question 10.
The molten state of NaCl is also called as ………………………… .
(a) solid state
(b) semi-solid
(c) gaseous state
(d) fused state
Answer:
(d) fused state

Question 11.
Substance used to make hard water soft is ………………………… .
(a) Na₂CO₃.10H₂O
(b) Na₂CO₃.H₂O
(c) NaCO₃.10H₂O
(d) NaCO₃.H₂O
Answer:
(a) Na₂CO₃.10H₂O

Question 12.
The fixed number of molecules of water in alum is ………………………… .
(a) 24
(b) 10
(c) 7
(d) 2
Answer:
(a) 24

Question 13.
Chlorine gas is a strong ………………………… agent.
(a) reducing
(b) oxidising
(c) neutral
(d) acidic
Answer:
(b) oxidising

Question 14.
Bleaching powder is ………………………… in colour.
(a) brownish red
(b) yellowish-white
(c) pinkish brown
(d) greenish blue
Answer:
(b) yellowish-white

Question 15.
Soap is ………………………… in nature.
(a) acidic
(b) basic
(c) neutral
(d) fuming
Answer:
(b) basic

Question 16.
Melting point of NaCl is ………………………… .
(a) 400°C
(b) 100°C
(c) 800°C
(d) 600°C
Answer:
(c) 800°C

Question 17.
Rock salt is ………………………… in colour.
(a) black
(b) white
(c) brown
(d) blue
Answer:
(c) brown

Question 18.
Strong odour in swimming pool is due to ………………………… .
(a) chlorine gas
(b) impurities
(c) calcium carbonate
(d) calcium hydroxide
Answer:
(a) chlorine gas

Question 19.
Molecular formula of sodium bicarbonate is ………………………… .
(a) NaHCO₃
(b) Na₂HCO₃
(c) Na₂HCO₂
(d) NaHCO₂
Answer:
(a) NaHCO₃

Question 20.
Soap is ………………………… in nature.
(a) radioactive
(b) natural
(c) acidic
(d) basic
Answer:
(d) basic

Question 21.
The molecular formula for Magnesium bromide is ………………………… .
(а) MgBr
(b) MgBr₂
(c) Mg₂Br₂
(d) Mg₂Br
Answer:
(b) MgBr₂

Fill in the blanks and rewrite the complete statements:

(1) 25% of NaCl is known as
(2) gas is released when bleaching powder is added to water.
(3) Washing soda is as it absorbs moisture if left exposed to air.
(4) is used to make hard water soft.
(5) Molecular formula for Alum is
(6) is used in blood test for diagnosing anaemia.
(7) High grade of and are used as raw material to manufacture bathing soap.
(8) Pickles, jams and sauce contain small quantities of and
(9) Excessive consumption of foods with added food colours leads to diseases like
(10) Melting point of Teflon is
(11) Anodizing is done by
(12) The red blood cell count increases in the disease
(13) Magnesium sulphate (MgS04.7H20) is also called
Answer:
(1) Brine
(2) Chlorine
(3) hygroscopic
(4) Na₂CO₃ (Washing soda)
(5) K₂SO₄.Al₂(SO)₃.24H₂O
(6) Blue Vitriol
(7) fats, oils
(8) lead, mercury
(9) ADHD (Attention Deficit Hyperactivity Disorder)
(10) 327°C
(11) Electrolysis
(12) Polycythemia
(13) Epsom salt
(14) Soap

State whether the following statements are true or false. Correct the false statements.
(1) Bleaching powder is used in preparation of chloroform which is used as an anaesthetic.
(2) On addition of universal indicator the colour of table salt changes to pink.
(3) Borax is Na₂B₄O₇.9H₂O.
(4) Boron -10 is used to cure bone cancer.
(5) Clinical deo contains 20 to 25% of aluminium.
(6) NaHCO₃ is sodium carbonate.
(7) Soap is acidic in nature.
(8) Baking powder is neutral in nature.
(9) POP is crystalline in nature.
(10) pH value of universal indicator is 0 – 7.
(11) Sodium chloride is formed by neutralization reaction between sodium hydroxide and calcium carbonate.
(12) Boiling point of NaCl is 800 °C.
(13) Molten state of NaCl is also called as solid state.
(14) Mineral halite is an example of Rock Salt.
(15) Sodium bicarbonate is used to reduce acidity.
(16) Bleaching powder is also called as chloride of lime.
(17) Bleaching powder is obtained by reaction of chlorine gas with slaked lime.
(18) Bleaching powder available in market is classified on the basis of colour.
(19) The hard water becomes soft on adding baking soda (NaHCO₃)
Answer:
(1) True
(2) False. On addition of universal indicator the colour of table salt changes to green.
(3) False. Borax is Na₂B₄O₇.9H₂O
(4) False. Boron – 10 is used in treatment of brain tumour.
(5) True
(6) False. NaHCO₃ is sodium bicarbonate.
(7) False. Soap is basic in nature.
(8) False. Baking powder is basic in nature.
(9) False. POP is amorphous in nature.
(10) False. pH value of universal indicator is 0 -14.
(11) False. Sodium chloride is formed by a neutralization reaction between sodium hydroxide and hydrochloric acid.
(12) False. Melting point of NaCl is 800°C.
(13) False. Molten state of NaCl is also called as fused state.
(14) True
(15) True
(16) True
(17) True
(18) False. Bleaching powder available in market is classified on the basis of percentage of chlorine present in it.
(19) False. Hard water becomes soft on adding washing soda (Na₂CO₃.10H₂O)

Name the following:

Question 1.
Important salts found in sea water.
Answer:
Magnesium chloride, Potassium chloride

Question 2.
Chemical used in preparation of breads and cakes to make them soft.
Answer:
Sodium bicarbonate

Question 3.
Gas liberated when bleaching powder is added to CO₂ gas.
Answer:
Chlorine (Cl₂) gas.

Question 4.
Salt used in refining petroleum
Answer:
Sodium carbonate (Na₂CO₃)

Question 5.
Chemical formula of bleaching powder
Answer:
CaOCl₂

Question 6.
The chemical formula of Sodium hydrogen carbonate.
Answer:
NaHCO₃

Question 7.
Nature of soap.
Answer:
Basic

Question 8.
Molecular formula for Magnesium bromide
Answer:
MgBr₂

Question 9.
Melting point of NaCl
Answer:
800 °C

Question 10.
Two examples of Rock Salt
Answer:
Mineral halite and Himalayan rock salt.

Question 11.
Uses of sodium bicarbonate
Answer:
To prepare breads, cakes and dhokla

Question 12.
Constituents of baking powder.
Answer:
Baking soda and mild acid (tartaric acid)

Question 13.
Substance used to make hard water soft.
Answer:
Washing soda i.e. Na₂CO₃.10H₂O.

Question 14.
Radioactive isotopes used in treatment of bone cancer.
Answer:
Strontium – 89, Strontium – 90, Samarium -153, Radium – 223

Question 15.
Use of Strontium 89 and strontium 90.
Answer:
Treatment of bone cancer.

Select the odd man out:

Question 1.
Sodium sulphate, Barium chloride, Magnesium sulphate, Bleaching powder.
Answer:
Bleaching powder, all others are crystalline salt with water of crystallization while bleaching powder is not.

Question 2.
Strontium – 89, Strontium – 90, Radium – 223, Iodine -123.
Answer:
Iodine -123, it is used to cure hyperthyroidism while others are used to cure bone cancer.

Question 3.
Soap, Toothpaste, Baking soda, Curd.
Answer:
Curd, it is acidic in nature while others are basic in nature.

Question 4.
Na₂CO₃.10H₂O, Na₂SO₄.10H₂O, BaCl₂.2H₂O, CaOCl₂
Answer:
CaOCl₂, it is amorphous in nature while rest are crystalline in nature.

Question 5.
Boron-10, Iodine – 131, Cobalt – 60, Iodine – 123.
Answer:
Iodine -123, it is used in hyperthyroidism while rest are used in treatment of brain tumour.

Question 6.
Na₂SO₄, K₃PO₄, MgBr₂, HCl.
Answer:
HCl, rest all are salts but HCl is an acid.

Write the correlated terms:

(1) Washing Powder : Basic :: Milk : ……………………………
(2) Na₂SO₄: Sodium sulphate :: K₃PO₄ : ……………………………
(3) CaOCl₂: Calcium Oxychloride : : NaHCO₃ : ……………………………
(4) Borax : 10H₂O : : Alum : ……………………………
(5) Sodium Sulphate : Na₂SO₄.10H₂O : : Magnesium Sulphate : ……………………………
(6) Bathing soap : High grades fats and oils :: Washing soap : ……………………………
(7) Radium – 23 : Bone cancer :: Phosphorus – 32 : ……………………………
(8) Iodine -123 : Hyperthyroidism :: Iodine -131 : ……………………………
(9) Clinical deo : 20-25% of aluminium : : Antiperspirant deo : of aluminium chlorohydrate : ……………………………
(10) Sodium carbonate : Na₂CO₃ : : Sodium bicarbonate : ……………………………
(11) Curd : Acidic : : Soap : ……………………………
(12) Calcium Carbonate : CaCO₃ : : Magnesium bromide : ……………………………
(13) Baking Soda : NaHCO₃ : : Washing Soda : ……………………………
(14) Baking Soda : Breads and Cakes : : Washing Soda : ……………………………
(15) Borax : Na₂B₄O₇.10H₂O : : Alum : ……………………………
Answer:
(1) Acidic
(2) Potassium phosphate
(3) Sodium hydrogen carbonate
(4) 24H₂O
(5) MgSO₄.7H₂O
(6) Low-grade fats and oils
(7) Polycythemia
(8) Tumour detection
(9) 15%
(10) NaHCO.
(11) Basic
(12) MgBr₂
(13) Na2CO₃.10H₂O
(14) Hard water soft
(15) K₂SO₄.Al₂(SO₄)₃.24H₂O

Match the columns:

Question 1.

Answer:
(1 – c),
(2 – d),
(3 – b),
(4 – a)

Question 2.

Answer:
(1 – d),
(2 – a),
(3 – b),
(4 -c)

Give scientific reasons:

Question 1.
Baking soda is used while making cakes.
Answer:

• Baking soda is chemically known as sodium bicarbonate.
• On heating, sodium bicarbonate decomposes to form sodium carbonate, water and carbon dioxide (CO,).
• The carbon dioxide produced is released due to which the cake becomes soft and spongy.
• Hence, baking soda is used to make cake spongy and soft.

Question 2.
Baking soda is used to reduce acidity in the stomach.
Answer:

• Baking soda is used as a medicine (antacid). When it is taken, it undergoes hydrolysis to give sodium hydroxide in the stomach. Thus, sodium hydroxide neutralizes the hydrochloric acid produced by gastric juice and gives relief to the patient from acidity.
  

Question 3.
Tap water and water in swimming pool has a typical strong odour in the rainy season.
Answer:

• Tap water and water in swimming pool has a typical strong odour in the rainy season, it is the odour of the chlorine gas that is used to destroy the microbes in the water.
• Chlorine gas is a strong oxidizing agent and therefore, it has a strong disinfecting as well as bleaching action.
• Chlorine is inconvenient to handle because of its gaseous state. Instead, the solid bleaching powder which has the same effect is more convenient to use.
• Bleaching powder undergoes slow decomposition due to the carbon dioxide in air and chlorine gas is released. Bleaching powder gets its property because of this release of chlorine gas.
  

Question 4.
Sodium carbonate is added to hard water to make it soft.
Answer:

• The hardness of water is due to the presence of chlorides and sulphates of calcium and magnesium in it.
• Na₂CO₃ is added to it to soften such water and make it suitable for use.
• The reaction with Na₂CO₃ causes the formation of insoluble carbonate salts of magnesium and calcium thus making the water soft.
  

Question 5.
Alum is used in the process of water purification.
Answer:

• Alum is used in the process of water purification because of property of coagulation.
• The solid impurities in water come together, become heavy and settle to the bottom.
• As a result, the water above becomes clear.

Question 6.
Overconsumption of artificial food colours should be avoided?
Answer:

• The overconsumption of artificial food colours should be avoided because they can be detrimental to health.
• Food colours added to pickles, jam and sauce contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
• Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

Question 7.
Artificial colours in Rang Panchami should be used cautiously.
Answer:

• We regularly use artificial colours on Rang Panchami.
• The red colour used on Rang Panchami is very dangerous. It contains a high proportion of mercury in it.
• This poses risks like blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores etc.
• Therefore, it is necessary that artificial colours are used cautiously.

Question 8.
There are various brands of bleaching powder in the market.
Answer:

• When bleaching powder comes in contact with air, it reacts with carbon dioxide to form calcium carbonate and releases chlorine gas. CaOCl₂ + CO₂ → CaCO₃ + Cl₂ ↑ (from air)
• This generated chlorine is known as “available chlorine.”
• On the basis of the percentage of “available chlorine” various brands of bleaching powder are available in the market.

Question 9.
We use anodized cooking utensils like griddles and cookers.
Answer:

• Anodizing is process of forming a protective rayer of hydrated aluminium oxide on utensils.
• Due to anodizing, the surface of the cooking utensils become non-standing, non-toxic and non-reactive with the ingredients of the foot.
• These utensils get heated faster and withstand high heat.
• Also the amount of butter, ghee or oil used to cook food in these type of utensils is neglible.
• These utensils are tough, durable and resistant to corrosion.
• Hence, we use anodized cooking utensils like gridders and cookers.

Explain the following chemical reactions with the help of balanced equations :

Question 1.
Sodium hydroxide reacts with dilute Hydrochloric acid.
Answer:
When Sodium hydroxide reacts with dilute Hydrochloric acid, it forms sodium chloride and water.
This is a neutralization reaction.

Question 2.
When an electric current is passed through a saturated solution of sodium chloride (brine)
Answer:
When an electric current is passed through a saturated solution of sodium chloride (brine) it is electrolysed and hydrogen gas is released at the cathode while chlorine gas is released at the anode. Also, an important basic compound NaOH is formed in the cell.

Question 3.
Baking soda (Sodium hydrogen carbonate) reacts with dilute hydrochloric acid.
Answer:
When Sodium bicarbonate (Sodium hydrogen carbonate) reacts with dilute hydrochloric acid, it gives sodium chloride, water and carbon dioxide gas is liberated.

Question 4.
Bleaching powder is exposed to air.
Answer:
When bleaching powder is exposed to air, it undergoes slow decomposition due to the carbon dioxide in air and chlorine gas is released.

Question 5.
When dry slaked lime reacts with chlorine gas.
Answer:
When dry slaked lime reacts with chlorine gas, it gives bleaching powder.

Question 6.
Bleaching powder reacts with dilute sulphuric acid.
Answer:
Dilute sulphuric acid reacts rapidly with bleaching powder to form calcium sulphate and release chlorine gas completely.

Question 7.
Bleaching powder reacts with dilute hydrochloric acid.
Answer:
Dilute hydrochloric acid reacts rapidly with bleaching powder to form Calcium chloride and release chlorine gas completely.

Question 8.
Sodium carbonate reacts with magnesium chloride.
Answer:
When Sodium carbonate reacts with magnesium chloride, it forms insoluble magnesium carbonate and sodium chloride. This reaction is used to make hard water soft.

Question 9.
Crystalline sodium carbonate is exposed to air.
Answer:
When crystalline sodium carbonate is exposed to air it loses its water of crystallization readily and a white powder is obtained. This powder is called washing soda.

Question 10.
Sodium carbonate reacts with sulphuric acid.
Answer:
When sodium carbonate reacts with sulphuric acid it forms sodium sulphate, water and carbon dioxide gas is liberated.

Distinguish between;

Question 1.
Washing soda and Baking soda
Answer:

Question 2.
Bathing soap and Washing soap
Answer:

Answer the following:

Question 1.
Give the properties and uses of Sodium bicarbonate.
Answer:
Properties and uses of sodium bicarbonate

• (i) NaHCO₂ reacts with moist litmus paper and red litmus turns blue which means that it is basic in nature.
• (ii) It is used to make bread, cake, dhokla.
• (iii) Being basic in nature it is used to reduce acidity in the stomach.
• (iv) NaHCO₃ is used to make the active substance CO₂ in the fire extinguisher.
• (v) Baking soda is used to clean an oven.

Question 2.
Give the properties and uses of washing soda.
Answer:
Properties and uses of washing soda :

• Washing soda is a whitish and odourless powder at room temperature.
• Litmus has a blue colour in its aqueous solution.
• It is hygroscopic, that is, it absorbs moisture if left exposed to air.
• It is used mainly for washing clothes.
• Sodium carbonate is used in the glass and paper industry and also in refining of petrol.

Question 3.
Name some substances in our daily use which contain water of crystallization.
Answer:

• Alum (Potash alum – K₂SO₄.Al₂(SO₄)₃.24H₂O)
• Borax (Na₂B₄O₇.10H₂O)
• Epsom salt (Magnesium sulphate MgSO₄.7H₂O)
• Barium chloride (BaCl₂.2H₂O)
• Sodium sulphate (Glauber’s salt Na₂SO₄.10H₂O)

Question 4.
Give the uses of radioactive isotopes in the measurement of thickness, density and level.
Answer:
Measurement of thickness, density and level:

• It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness.
• In the manufacturing process, a radioactive substance is placed on one side and an instrument to measure radiation on the other.
• The radiation read by the measuring instrument varies with the thickness of the sheet.
• Material inside a packing can also be examined by the same technique.

Question 5.
Give the uses of radioactive isotopes in Luminescent paint and radioluminescence.
Answer:
Luminescent paint and radioluminescence:

• The radioactive substances radium, promethium, tritium with some phosphour are used to make certain objects visible in the dark, for example, the hands of a clock, and certain other objects.
• Krypton-85 is used in HID (High Intensity Discharge) lamps while promethium-147 is used in portable X-ray units as the source of beta rays.

Question 6.
Give the uses of radioactive isotopes in Field of agriculture.
Answer:
Field of agriculture:

• The genes and chromosomes that give seeds properties like fast growth, higher productivity, etc. can be modified by means of radiation.
• The radioactive isotope cobalt-60 is used for food preservation.
• Onions, potatoes are irradiated with gamma rays from cobalt-60 to prevent their sprouting.
• Strontium-90 is used as a tracer in the research on various crops.

Question 7.
Give the uses of dyes.
Answer:
Uses of dyes :

• They are used for colouring cloth and hair.
• Fluorescent colours are used to make street boards that are visible at night.
• Dyes are used to polish leather shoes, purses and chappals.

Question 8.
What are the adverse effects of dyes?
Answer:
Adverse effects dyes :

• Dyeing hair can have adverse effects like hair fall, damage to hair texture, burning of skin, adverse effect on eyes, etc.
• Lipstick contains a dye named carmine. It does not affect lips but causes stomach disorders.
• Excessive use of plants for making natural dyes results in deterioration of the environment.

Question 9.
Give the uses of teflon.
Answer:
Uses of teflon :

• Teflon is a poor conductor of electricity. Therefore, Teflon clad wires and parts are used in high technology electronic instruments.
• It is used for making non-stick kitchenware.
• The coloured metal sheets of two-wheelers and four-wheelers are given a Teflon coating to protect them from damage due to high temperature and rain.

Question 10.
What is ceramic? Give examples.
Answer:

• Ceramic is a heat resistant substance formed by kneading an inorganic substance in water and then shaping it and hardening it by heating.
• Pots made by a potter, Mangalore roofing tiles, construction bricks, pottery, terracotta articles are some examples of common ceramic articles that we see around.

Question 11.
Give the uses of ceramics.
Answer:

• Ceramics can withstand high temperatures without decomposing. Ceramic is brittle, water-resistant and an electrical insulator.
• Therefore, it is used in electrical instruments, for coating the interior of a kiln, the outer surfaces of ships and blades of jet engines.
• A certain type of ceramic tiles are fixed on the outer layer of a space shuttle. Some types of ceramics are used as superconductors.

Question 12.
What is brine? What happens when ^th of this solution is evaporated?
Answer:

• The 25% aqueous solution of salt is called saturated brine.
• When th of this solution is evaporated the dissolved salt gets crystallized and salt gets separated from the solution.

Question 13.
What is baking soda? Give its chemical name and molecular formula.
Answer:

• Baking soda is a white non-crystalline powder.
• Its chemical name is sodium hydrogen carbonate or sodium bicarbonate and its molecular formula is NaHC03.

Question 14.
Give two uses of Blue vitriol.
Answer:

• Blue vitriol is used in the blood test for diagnosing anaemia.
• Bordeaux mixture which is a mixture of slaked lime and blue vitriol is used as a fungicide on fruits like grapes and musk melon.

Question 15.
What is radioactivity and what are radioactive substances?
Answer:

• Elements with a high atomic number such as uranium, thorium, radium have a property of spontaneously emitting invisible, highly penetrating and high energy radiation. This property is called radioactivity.
• A substance having this property is called a radioactive substance.

Question 16.
What can you say about the uses of radioactive isotopes?
Answer:

• It is a misconception that radioactive elements are used only for making an atom bomb.
• Radioactive isotopes are used in various fields such as scientific research, agriculture, industry, medicine, etc.
• Radioactive substances are used in two ways.
• By using the radiation alone.
• By using the radioactive element itself.

Question 17.
Give the uses of radioactive isotopes in Radiography.
Answer:

• Internal cracks and voids in cast iron articles and iron solder can be detected with the help of gamma rays.
• For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera.
• This technique is used for detecting flaws in metalwork.

Question 18.
Give the uses of radioactive isotopes in ceramic articles.
Answer:

• Luminous colours are used to decorate ceramic tiles, utensils, plates, etc.
• Earlier uranium oxide was used in these paints.

Question 19.
What is a dye?
Answer:
The coloured substance which on applying to an article, imparts that colour to the article, is called a dye

Question 20.
What is done to fix a dye on the cloth ?
Answer:

• A mordant is to be used to fix the colour after dyeing a cloth.
• A mordant is a chemical binding agent that adheres well to both the fibers and the dye.

Question 21.
What is Teflon? Give its chemical name.
Answer:

• Teflon is the polymer of tetrafluoroethylene.
• Its chemical name is polytetrafluoroethylene (C₂F₄)_n

Question 22.
What is powder coating? Why is it done?
Answer:

• Powder coating is a method of applying a layer harder than paint on the surface of plastic, medium density fibre (MDF).
• Board and iron object to make them attractive, durable and to prevent rustihg respectively.

Question 23.
Give the properties of ceramics.
Answer:

• Ceramics can withstand high temperatures without decomposing.
• Ceramic is brittle, water resistant and an electrical insulator.

Question 24.
How is bone china made? How is it different from porcelain?
Answer:

• Bone china is made by adding some ash of animal bones in the mixture of china clay, feldspar and fine silica while making porcelain.
• This ceramic is harder than porcelain.

Question 25.
What compounds are used instead of clay for making advanced ceramic?
Answer:
Oxides like Alumina (Al₂O₃), Zirconia (ZrO₂) Silica (SiO₂) and some other compounds like silicon carbide (SiC), boron carbide (B₄C) are used instead of clay for making advanced ceramic.

Question 26.

What is sintering?
Answer:

• Advanced ceramics requires a temperature of 1600 to 1800 °C and an oxygen-free atmosphere for firing.
• This process is called sintering.

Write short notes on :

Question 1.
Chernobyl disaster.
Answer:

• On 26th April 1986, the graphite reactor in the Chernobyl atomic power plant exploded, and suddenly the radioactive isotopes and radiation came out.
• Due to this episode, radioactive isotopes entered the human body through water and land and caused genetic disorders.
• These got carried further into the next generation.
• Thyroid disorders increased in children as well as adults.
• As a result, the incidence of throat diseases is greater there than in other places.

Question 2.
Food colours.
Answer:

• Food colours are mixed in most soft drinks and foodstuffs available in the market.
• These food colours are in the form of powders, gels and pastes.
• Food colours are used in domestic as well as commercial products.
• Certain colours and essences are added to ice cream, ice candies, sauces, fruit juices, cold drinks, pickles, jams and jellies.
• Food colours are often found to be added to packaged meat (chicken, mutton), chilli powder, turmeric, sweets and other similar substances so as to give them a good colour.
• Food colours are natural as well as artificial.
• The food colours prepared from seeds, beetroot, flowers and fruit concentrate are natural.
• Tetrazene, sunset yellow are artificial food colours used extensively.
• However, over-consumption of artificial food colours can be detrimental to health. Therefore, usage of natural food colours is always good.

Question 3.
Anodizing.
Answer:

• A protective layer is formed naturally on the surface of aluminium metal by reaction with oxygen in air.
• In the anodizing process, this layer can be made of the desired thickness.
• Anodizing is done by electrolysis.
• Dilute sulphuric acid is taken in the electrolytic cell and the aluminium article is dipped in it as the anode.
• When an electric current is passed, hydrogen gas is released at the cathode and oxygen gas at the anode.
• A reaction with oxygen occurs and a layer of hydrated aluminium oxide is formed on the anode, i.e. the aluminium article.
• This layer can be made attractive by adding colour in the cell during electrolysis.

Answer the following questions:

Question 1.
What are salts? Give their source.
Answer:

• The ionic compounds which do not contain H+ and OH ions and contain only one kind of cation and anion are called simple salts.
• For example, Na₂SO₄, K₃PO₄, CaCl₂.
• The sea is said to be a rich source of salts of various elements such as chlorine, sodium, magnesium, potassium, calcium, bromine.
• The important salts found in sea water are:
  (a) Sodium chloride
  (b) Magnesium chloride
  (c) Magnesium sulphate
  (d) Potassium chloride
  (e) Calcium carbonate
  (f) Magnesium bromide

Question 2.
Which are the three kinds of salts depending on their pH value? How are they formed?
Answer:
The three kinds of salts depending on their pH value are:

Neutral salts:
Salt is neutral when its pH value is 7. Such a salt is made from a strong acid and a strong base.

Acidic salts:
The pH value of a salt made from a strong acid and a weak base is less than 7 and it is acidic.

Basic salts:
The pH value of a salt made from a weak acid and strong base is more than 7 and it is basic.

Question 3.
Which is the most used salt? What is its chemical name? How is it formed?
Answer:

• Table salt, or common salt, which gives a salty taste to food, is the most used of all salts.
• Its chemical name is Sodium chloride.
• Sodium chloride is formed by a neutralization reaction between sodium hydroxide and hydrochloric acid.
• Chemical reaction
• This is a neutral salt and the pH value of its aqueous solution is 7.

Question 4.
How is bleaching powder obtained?
Answer:

• Bleaching powder is obtained by the reaction of chlorine gas with slaked lime.
• Chemical reaction

Question 5.
How is hard water from well converted to soft water?
Answer:

• The hard water from a well or a bore-well becomes soft on adding washing soda and we come to know this from the lather formed on it.
• The hardness of water is due to the presence of chlorides and sulphates of calcium and magnesium in it.
• Na₂CO₃ is added to it to soften such water and make it suitable for use.
• The reaction with Na₂CO₃ causes the formation of insoluble carbonate salts of magnesium and calcium.
• Chemical reaction
  MgCl_2(aq) + Na₂CO_3(s) → MgCO_3(s) + 2NaCl_(s) Magnesium Sodium Magnesium Sodium chloride carbonate carbonate chloride

Question 6.
How is washing soda obtained from sodium carbonate?
Answer:

• Sodium carbonate is a water soluble salt of sodium.
• Crystalline sodium carbonate, on keeping, loses its water of crystallization readily and a white powder is obtained.
• This powder is called washing soda.
• Chemical reaction

Question 7.
How is soap prepared? Why it does not form lather with hard water?
Answer:

• When oil or animal fat is boiled with an aqueous solution of sodium or potassium hydroxide, sodium or potassium salts of carboxylic acids (fatty acids) are formed.
• These salts are called soap.
• When soap is mixed with hard water, calcium and magnesium salts of fatty acids are formed.
• These being water insoluble, they form a precipitate and that is why lather is not formed.

Question 8.
What are the harmful effects of artificial food colours?
Answer:

• Food colours added to pickles, jams and sauces contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
• Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

Question 9.
Which is the main source of colour for preparing a natural dye?
Answer:

• Plants are the main source of colour for preparing a natural dye.
• Roots, leaves, flowers, bark, fruits, seeds, fungus and pistils are used for making dyes.
• In Kashmir a very good dye is made from saffron, which is used to dye fibers from which saris, shawls and dresses are made.
• These are very costly. The use of henna leaves to colour hair is safe for health.

Question 10.
How are artificial colours harmful to us?
Answer:

• We regularly use artificial colours on Rang Panchami.
• The red colour used on Rang Panchami is very dangerous.
• It contains a high proportion of mercury in it.
• This poses risks like blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores, etc.
• Therefore, it is necessary that artificial colours are used cautiously.

Question 11.
What are the harmful effects of deodorants?
Answer:

• Aluminium – Zirconium compounds are the most harmful chemicals in deodorants. Disorders like headache, asthma, respiratory disorders, heart disease are likely to occur without our knowledge.
• There is a possibility of various skin disorders and also skin cancer due to the aluminium chlorohydrates.

Question 12.
How is a ceramic article made?
Answer:

• When clay is kneaded in water, shaped and then fired in a kiln at a temperature of 1000 to 1150 °C, a porous ceramic is formed.
• To overcome the porosity, the fired object is covered with finely ground glass powder suspended in water (glaze) and is then fired again. As a result, the surface of the ceramic becomes shiny and its porosity disappears.

Question 13.
What is porcelain? How is it made?
Answer:

1. Porcelain is a hard, translucent and white coloured ceramic. It is made by using the white clay called kaolin, found in China. Glass, granite and the mineral feldspar is mixed with kaolin and kneaded with water.
2. The resulting mixture is shaped and fired in a kiln at a temperature of 1200 to 1450 °C. On firing again after glazing, beautiful articles of porcelain are obtained.

Answer the following questions:

Question 1.
What are the constituents of baking powder? Where is the baking powder used?
Answer:

• Baking powder consist of 30% sodium bicarbonate, 5-12% monocalcium phosphate and 21-26% sodium aluminium sulphate.
• Baking powder is a leavening agent and is used for increasing the volume and lightening the texture of baked goods.

Question 2.
Take a piece of coloured cloth. Put some saturated solution of bleaching powder on a small part and observe what changes take place in the colour of the cloth.
Answer:
When bleaching powder is added to a piece of coloured cloth, the fabric looses its colour due to the oxidising reaction of the chlorine present in the bleaching powder.

Answer in detail:

Question 1.
Give the properties and uses of Sodium chloride.
Answer:
Properties and uses of sodium chloride:

• Common salt is a colourless and crystalline ionic compound. There is no water of crystallization in its crystalline structure.
• It is a neutral salt, salty in taste.
• This compound is used for the production of salts like Na₂CO₃, NaHCO₃.
• When an electric current is passed through a saturated solution of sodium chloride (brine), it is electrolysed and hydrogen gas is released at the cathode while chlorine gas is released at the anode.
• This method is used for production of chlorine gas. In this method an important basic compound NaOH is formed in the cell.
  2NaCl + 2H₂O → 2NaOH + Cl₂↑ + H₂↑
• When salt is heated to a high temperature (about 800 °C), it melts. This is called the fused state of the salt.
• When fused salt is electrolysed, chlorine gas is released at the anode and liquid sodium metal, at the cathode.

Question 2.
Give the properties and uses of Bleaching Powder.
Answer:
Properties and uses bleaching powder:

• Bleaching powder is a yellowish-white coloured solid substance.
• Its chemical name is Calcium oxychloride.
• It has a strong odour of chlorine gas.
• It is used for disinfection of drinking water at the water works and the water in the swimming pool.
• It is used for bleaching of cloth.
• It is used for disinfection by the road side and garbage sites.
• Dilute sulphuric acid and dilute hydrochloric acid react rapidly with bleaching powder to release chlorine gas completely.
  CaOCl₂ + H₂SO₄ → CaSO₄ + Cl₂ ↑ + H₂O CaOCl₂ + 2HCl → CaCl₂ + Cl₂ ↑ + H₂O
• Calcium oxychloride reacts slowly with carbon dioxide to form calcium carbonate and chlorine.
  CaOCl₂ + CO₂ → CaCOs + Cl₂ ↑

Question 3.
Explain with neat labelled diagram the nature of radioactive radiation.

Answer:

• When radioactive radiations are allowed to pass through two oppositely charged plates they get separated. This method was introduced by Rutherford in 1902.
• Rutherford and Willard studied the radiation emitted by radioactive substances.
• For this purpose, the rays were allowed to pass through an electrical field and a photographic plate was held in their path.
• It was found that the radiation was divided into three types.
• One type of radiation deviated slightly towards the negatively charged plate, while the second type of radiation deviated substantially towards the positively charged plate.
• However, the third type of radiation did not deviate at all in the electrical field.
• The rays which deviated slightly toward negatively charged plate are called alpha rays.
• Those which deviate substantially towards the positively charged plate are called beta rays and those which did not deviate at all are called gamma rays.

Question 4.
Give the characteristics of alpha, beta and gamma rays.
Answer:
Characteristics of alpha, beta and gamma rays are as given in the table.

Question 5.
Give the uses of radioactive isotopes in Medical science.
Answer:
Medical science:

• Polycythemia: The red blood cell count increases in the disease polycythemia. Phosphorus- 32 is used in its treatment.
• Bone cancer: Strontium-89, strontium-90, samarium-153 and radium-223 are used in the treatment of bone cancer.
• Hyperthyroidism: Enlargement of thyroid gland, weight loss in spite of appetite, insomnia are the symptoms of hyperthyroidism.
• It occurs due to overproduction of hormones by the thyroid gland. Iodine-123 is used in the treatment of hyperthyroidism.
• Tumour detection: Boron-10, iodine-131, cobalt-60 are used in the treatment of brain tumour, while arsenic-74 is used in detection of small tumours in the body.

Question 6.
What are the hazards of radioactive substances and radiation?
Answer:

• The central nervous system is affected by radioactive radiations.
• Hereditary defects are generated by bombardment of radiation on D.N.A in the body.
• Radioactive radiation can penetrate the skin, and causes diseases like skin cancer, leukemia.
• The radiative pollutants created due to explosions enter the body through air and it is difficult to control them.
• The radioactive pollutants released in the sea enter the bodies of fishes and through them enter the human body.
• The radioactive paint on the watch can cause cancer.
• The radioactive isotopes strontium-90 can enter the body through plants, fruits, flowers, cereals, milk, etc. and cause diseases like bone cancer, leukemia.

Question 7.
Why are deodorant used? Give their types and content.
Answer:

• Body odour is caused by the bacterial decomposition of the sweat. A deodorant is used to prevent this odour.
• Deodorants contain parabens (methyl, ethyl, propyl, benzyl and butyl) and also alcohol in large proportions. Aluminium compounds and silica are also used.
• Types of deodorants are :
  (a) Ordinary deo: It contains a smaller proportion of aluminium. It decreases the odour of the sweat.
  (b) Antiperspirant deo : This decreases the extent of sweating. It contains about 15% of aluminium chlorohydrate. It clogs the sweat pores on the skin.
  (c) Clinical deo : Some people sweat heavily and it has harmful effects on the skin. Clinical deo is meant for such people. It contains 20 to 25% aluminium. It is used during the night.

Question 8.
Explain how powder coating is done.
Answer:

• Powder coating is a method of applying a layer harder than paint on the surface of an iron object to prevent rusting.
• In this method, a polymer resin, a pigment and some other ingredients are melt, mixed, cooled and ground into a uniform powder.
• This powder is sprayed on the polished metal surface by electrostatic spray deposition (ESD).
• In this method, the particles of the powder are given an electrostatic charge due to which a uniform layer of the powder sticks to the metal surface.
• Then the object is heated in the oven along with the coating.
• A chemical reaction occurs in the layer, resulting in the formation of long cross-linked polymeric chains.
• This powder coating is highly durable, hard and attractive.
• Powder coating can be done on plastic and medium density fibre (MDF) board in day to day use as well.

Balbharati Maharashtra State Board 9th Std Science Textbook Solutions 

• Information Communication Technology (ICT) Class 9 Science Textbook Solutions
• Reflection of Light Class 9 Science Textbook Solutions
• Study of Sound Class 9 Science Textbook Solutions
• Carbon: An Important Element Class 9 Science Textbook Solutions
• Substances in Common Use Class 9 Science Textbook Solutions
• Life Processes in Living Organisms Class 9 Science Textbook Solutions
• Heredity and Variation Class 9 Science Textbook Solutions
• Introduction to Biotechnology Class 9 Science Textbook Solutions
• Observing Space: Telescopes Class 9 Science Textbook Solutions

Std 9 Science Chapter 1 Laws of Motion Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 1 Laws of Motion Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 1 Laws of Motion Question Answer Maharashtra Board

Class 9 Science Chapter 1 Laws of Motion Textbook Questions and Answers

1. Match the first column with appropriate entries in the second and third columns and remake the table.

2. Clarify the differences

A. Distance and displacement
Answer:

B. Uniform and non-uniform motion.
Answer:

3. Complete the following table.

4. Complete the sentences and explain them.

a. The minimum distance between the start and finish points of the motion of an object is called the ……….. of the object.
b. Deceleration is ………………………. acceleration
c. When an object is in uniform circular motion, its ………………………. changes at every point.
d. During collision ………………………. remains constant.
e. The working of a rocket depends on Newton’s ………………………. law of motion.

5. Give scientific reasons.

a. When an object falls freely to the ground, its acceleration is uniform.
Answer:

• When the body falls freely to the ground, there are equal changes in velocity of the body in equal intervals of time.
• Thus the acceleration of the body is constant, and it possesses uniform acceleration.

b. Even though the magnitudes of action force and reaction force are equal and their directions are opposite, their effects do not get cancelled.
Answer:

• Action and reaction forces act on different bodies.
• They don’t act on the same body, hence they cannot cancel each other’s effect.
• Hence, even though the magnitudes of action force and reaction force are equal, they do not cancel each other.

c. It is easier to stop a tennis ball as compared to a cricket ball, when both are traveling with the same velocity.
Answer:

• Momentum of an object depends on its mass as well as its velocity.
• Cricket ball is heavier than a tennis ball. Although they are thrown with the same velocity, cricket ball has more momentum than a tennis ball.
• The force required to stop a cricket ball is more than a tennis ball.
• Hence it is easier to stop a tennis ball than a cricket ball moving with same velocity.

d. The velocity of an object at rest is considered to be uniform.
Answer:

• When a body is at rest there is no change in velocity.
• A body with constant velocity is said to be in uniform motion.
• Hence, the state of rest is an example of uniform motion.

6. Take 5 examples from your surroundings and give an explanation based on Newton’s laws of motion.

7. Solve the following examples.

a) An object moves 18 m in the first 3 s, 22 m in the next 3 s and 14 m in the last 3 s. What is its average speed? (Ans: 6 m/s)
Answer:
Given:
Total distance (d) = 18 + 22 + 14 = 54 m
Total time taken (t) = 3 + 3 + 3 = 9 sec
To find:
Average speed = ?

The object moves with an average speed of 6 m/s.

b) An object of mass 16 kg is moving with an acceleration of 3 m/s². Calculate the applied force. If the same force is applied on an object of mass 24 kg, how much will be the acceleration? (Ans: 48 N, 2 m/s²)
Answer: