Category: Class 7

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 3 Properties of Natural Resources Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 3 Properties of Natural Resources

Class 7 Science Chapter 3 Properties of Natural Resources Textbook Questions and Answers

Fill in the blanks with the appropriate term.

Question 1.
The capacity of air to hold moisture depends upon the …………… of the air.
Answer:
temperature

Question 2.
Water does not have a …………… but has definite ………… and ………. .
Answer:
shape, volume, mass

Question 3.
While freezing, the ………….. of water is lowered.
Answer:
density

Question 4.
…………….. soil has pH 7.
Answer:
neutral

2. Why is the said that –

Question a.
Air is a homogeneous mixture of various gases.
Answer:

1. Air is made of oxygen, nitrogen, carbondioxide, water vapour and dust particles.
2. All these are in different proportions. Therefore air is a mixture.

Question b.
Water is a universal solvent.
Answer:

1. Water dissolves more substances than any other liquid. It dissolves solids, other liquids and even gases in it. Therefore, it is called as Universal solvent.
2. Water is used as a solvent in factories, laboratories, foodstuffs and in various types of biological processes occurring in the body such as digestion, excretion, etc.

Question c.
There is no alternative to water for cleaning purposes.
Answer:
Water is a universal solvent. It dissolves more substances than any other liquid so there is no alternative to water for cleaning purposes.

3. What will happen if……

Question a.
The amount of water vapour in the air increases.
Answer:
We feel the dampness or the humidity.

Question b.
Only one crop is grown repeatedly in the soil.
Answer:
The fertility of the soil decreases.

4. With whom should I pair up? 

Question a.

Column ‘A’	Column ‘B’
1. Air	a. Excretion
2. Water	b. Scattering of light
3. Soil	c. Plasticity

Answer:

Column ‘A’	Column ‘B’
1. Air	b. Scattering of light
2. Water	a. Excretion
3. Soil	c. Plasticity

5. State whether the following statements are true or false.

Question a.
Sandy soil has low capacity for holding water.
Answer:
True

Question b.
Sea water is a bad conductor of electricity.
Answer:
False. Sea water is a good conductor of electricity

Question c.
The substance in which a solute dissolves is called a solvent.
Answer:
True

Question d.
The pressure exerted by air is called atmospheric pressure.
Answer:
True

6. Explain the picture in your own words. 

Question a.
Explain the picture in your own words.

Answer:

• Diagram (a): Water is filled in the crack.
• Diagram (b): Water in the crack turns to ice due to decrease in temperature. When it turns to ice the volume increases and it expands. Due to expansion, the size of crack widens more than in diagram (a).

 7. Write answers to the following questions in your own words. 

Question a.
How is light scattered by the air?
Answer:
Air is a mixture of very fine particles of some gases, dust, smoke and moisture. When rays of light fall on these minute particles, the particles spread the light in all the directions. This natural phenomenon is called scattering of light.

Question b
Explain the various properties of water.
Answer:
Various properties of water are as follows:

1. It is a fluid substance because it can flow.
2. It does not have its own shape, it takes the shape of a container in which it is kept.
3. It has a definite volume.
4. It is a transparent liquid and it has no colour.
5. It is tasteless and odourless.
6. It is a universal solvent.

Question c.
Why is the density of seawater is more than that of rainwater?
Answer:
Seawater has many minerals dissolved in it as compared to rainwater. So due to more dissolved salts, density of seawater is more than that of rainwater.

Question d.
What is the importance of good soil structure?
Answer:
The fertility of soil depends upon soil structure. So importance of good soil structure is as follows: (a) Roots get sufficient supply of oxygen, (b) Water drainage is good therefore the roots of plants grow well.

Question e.
What are the various uses of soil?
Answer:
The uses of soil are as follows:
Plant conservation: To help plants grow. Water conservation: Soil holds water. As a result, by means of bunds and lakes, we can get water for use throughout the year.
Plasticity: (a) Soil can be given any required shape. This property of soil is called plasticity, (b) Because of its plasticity, we can use it to make articles of a variety of shapes, (c) These articles can be baked to make them hard, (d) Water storage earthen pots, earthen lamps, idols, bricks etc. are articles made from soil.

Question f.
What is the need and importance of soil testing from the point of view of farmers?
Answer:

1. The properties of the various ingredients of soil can be determined by soil testing.
2. During soil testing, the soil is examined for colour, texture and the proportion of organic matter in it.
3. Soil is tested to find out if there is a deficiency of any ingredients and to decide what measures should be taken to remove the deficiency. These information would enable the farmers to maintain the fertility of the soil.

Question g.
What is the importance of air in transmission of sound?
Answer:

1. Air is useful as a medium for the transmission of sound. Density of the air changes with temperature.
2. If the density of air increases, we can hear the sound more loud and clear.

Question h.
Why should a glass bottle completely filled with water never be kept in a freezer?
Answer:

1. Due to anomalous behaviour of water, when you cool water below 4°C, the volume of the water increases.
2. Therefore when the glass bottle completely filled with water is kept in a freezer, water expands on cooling and its volume increases so glass bottle breaks.
3. To avoid this, completely filled bottle is never kept in a freezer.

Project:

Question a.
Visit a soil testing laboratory. Learn the process of soil testing and share it with others.

Class 7 Science Chapter 3 Properties of Natural Resources Important Questions and Answers

Fill in the blanks with the appropriate term.

Question 1.
Air is a …………… of gases.
Answer:
mixture

Question 2.
Atmospheric pressure is the …………… in all the directions.
Answer:
same

Question 3.
…………… is used to measure atmospheric pressure.
Answer:
Barometer

Question 4.
As we go higher the sea level and the atmospheric pressure …………… .
Answer:
decreases

Question 5.
Pressure of air …………… when its velocity …………… .
Answer:
increases, decreases

Question 6.
…………… an effect of the difference in air pressure.
Answer:
Wind

Question 7.
The level of …………… in the air is determined by its capacity to hold water vapour.
Answer:
humidity

Question 8.
When the temperature of air is low, its capacity to hold the vapour is …………… .
Answer:
less

Question 9.
Air is useful as a …………… for the transmission of sound.
Answer:
medium

Question 10.
Water is a …………… substance.
Answer:
fluid

Question 11.
Ice is …………… than water.
Answer:
lighter

Question 12.
Density of ice is …………… than that of water.
Answer:
less

Question 13.
The space occupied by a substance is its …………… .
Answer:
volume

Question 14.
The storage of matter in a substance is its …………… .
Answer:
mass

Question 15.
The density of water is maximum at …………… °C.
Answer:
4°C

Question 16.
The substance in which the solute dissolves is called …………… .
Answer:
solvent

Question 17.
The particles of sandy soil are made of the mineral called …………… .
Answer:
silicon dioxide (quartz)

Question 18.
…………… soil has a highest water holding capacity.
Answer:
clay

Question 19.
…………… soil is red in colour.
Answer:
Terracotta

Question 20.
…………… soil is used in cosmetics.
Answer:
Multani

Question 21.
…………… is celebrated as World Soil Day.
Answer:
5th December

Question 22.
The excess of water vapour during the night or dawn is transformed into ………….. .
Answer:
dew

Question 23.
Under ordinary conditions atmospheric pressure at sea level is …………… Newtons per square mater.
Answer:
101400

Question 24.
Swedish Scientist …………… put forth the important principle that the pressure of air decreases when its velocity increases.
Answer:
Daniel Bernoulli

Question 25.
When rays of light fall on fine particles of air, the particles spread light in all the directions, this is called …………… of light.
Answer:
Scattering

Question 26.
…………… soil is easy to plough but less fertile.
Answer:
Sandy

Say whether true or false, correct and rewrite the false statements.

Question 1.
Terracotta soil is white in colour.
Answer:
False. Terracotta soil is red in colour

Question 2.
The fertility of soil depends upon soil structure.
Answer:
True

Question 3.
Multani soil is used to make statues and idols.
Answer:
False. Shadu soil is used to make statues and idols

Question 4.
Clay soil has the maximum proportion of small particles.
Answer:
True

Question 5.
Silt soil is not as ploughable as sandy soil.
Answer:
True

Question 6.
The colour of soil near land surface is darker than the colour of the lower layers.
Answer:
True

Question 7.
Kerosene is a universal solvent.
Answer:
False. Water is an universal solvent

Question 8.
The density of substance is the inter-relation between the volume and mass of a substance.
Answer:
True

Question 9.
Water is lighter than ice.
Answer:
False. Ice is lighter than water

Question 10.
Rotation of crops decreases the fertility of the soil.
Answer:
False. Rotation of crop increases the fertility of the soil.

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
1. Concept of pH	a. pH higher than 7.5
2. Acidic Soil	b. pH 6.5 – 7.5
3. Neutral Soil	c. pH less than 6.5
4. Alkaline Soil	d. Sorensen

Answer:

Column ‘A’	Column ‘B’
1. Concept of pH	d. Sorensen
2. Acidic Soil	c. pH less than 6.5
3. Neutral Soil	b. pH 6.5 – 7.5
4. Alkaline Soil	a. pH higher than 7.5

Write short answers.

Question 1.
What is atmospheric pressure?
Answer:
The molecules of the gases in the air are in constant motion. When these molecules strike a body, they create pressure on that body. This pressure of air is called atmospheric pressure.

Question 2.
What is Bernoulli’s principle?
Answer:
Bernoulli’s principle is that the pressure of air ‘ decreases when its velocity increases while the pressure of air increases when its velocity decreases.

Give scientific reasons.

Question 1.
When the piston of a syringe is released, it is immediately pushed in.
Answer:

1. On pulling the piston of a syringe with the inlet hole of the syringe closed, more space becomes available to the air in the syringe, and it becomes rarified.
2. As a result, the pressure of the air in the syringe is lowered.
3. Comparatively the pressure of the outside air is very high. So when the pulled out piston is A released, it is immediately pushed in.

Question 2.
Water droplets are seen on the outer surface of a glass having ice cubes in it.
Answer:

1. Due to the ice cubes in the glass, the air surrounding the glass cools down.
2. As the water vapour in this air cools down, it condenses and gets transformed into water.
3. It is this water that collects on the outer surface of the glass.

Question 3.
Early morning dew drops are found on the grass.
Answer:

1. During the dawn (early morning) when the temperature of air is low, its capacity to hold the vapour is less.
2. At such times, the excess vapour is transformed into water droplets and we call them as dew drops.

Question 4.
During the afternoon we feel that the air is dry.
Answer:

1. In the afternoon, when the temperature of the air is high, the capacity of the air to hold the moisture also increases.
2. Then, compared to its full capacity to hold water the proportion of moisture in the air is less and we feel that the air is dry.

Question 5.
Earth’s surface remains warm and suitable for the living world on the earth.
Answer:

1. The earth receives energy from the sun. This energy is reflected by the earth in the form of heat.
2. The constituents of air surrounding the earth, such as water vapour, carbon dioxide, absorb a part of this heat and give it to the other constituents of air.
3. So the Earth’s surface remains warm and suitable for the living world on the earth.

Question 6.
We can hear the whistle of a distant train clearly early in the morning in winter.
Answer:

1. The density of air changes due to change in its temperature.
2. In winter, temperature is low so the density of the air is more. So we can hear the whistle of a distant train clearly early in the morning in winter.

Question 7.
Ice floats on water.
Answer:

1. When water freezes means it transforms into the soild state therefore its volume increases.
2. When volume increases its density decreases
3. Therefore, density of ice is less than the water, so ice floats on water.

Question 8.
In cold countries aquatic animals remain alive even after the rivers or lakes freeze in water.
Answer:
1. Due to anomalous behaviour of water, in cold countries when water gets cool and turn to ice, its volume increases, so its density decreases
2. Due to less density ice floats on water.
3.  (a) Ice is a bad conductor of heat and electricity, (b) It doesn’t allow outside heat to go from the ice to water so water temperature below the ice doesn’t change, (c) It remains as water so aquatic animals remain alive even after the rivers or lakes freeze in winter.

Question 9.
It is easier to swim in the sea than in a well or a lake.
Answer:

1. Sea water is saline. It contains salt whereas it is not so in well or a lake water.
2. Due to salts dissolved in sea water, density of sea water is more, so the swijnmer will not sink.
3. Hence, it is easier to swim in the sea than in a well or a lake.

Question 10.
Sandy soil is less fertile.
Answer:

1. Sandy soil is made up of large particles and these particles of sandy soil are made of the mineral called silicon dioxide.
2. These particles do not dissolve in water therefore soil has very little capacity to supply nutrients, so sandy soil is less fertile.

Question 11.
China clay is used for making crockery.
Answer:
China clay is used for making crockery because on heating, this clay acquires a glaze and hardness. It can be moulded into any shape and being a bad conductor of heat, it is easy to handle.

Answer the following:

Question 1.
Write the properties of air.
Answer:

1. Air is a mixture of gases.
2. Air has mass and volume.
3. It spreads in all directions.
4. It exerts pressure.
5. It is colourless.

Question 2.
Name the tests for finding out the characteristic of soil. Describe any one method of it.
Answer:
There are two tests for finding out the characteristics of soil: (1) pH (2) electrical conductivity tests.
1. pH tests: The Danish scientist Sorensen put forth the concept of pH, based on the concentration of hydrogen ions. To determine the pH of soil, a mixture of water and soil in the proportion of 1 : 2 is taken and tested using several indicators.
Accordingly, soil may be found to be one of the following types.

• Acidic soil – pH less than 6.5
• Neutral soil – pH 6.5 – 7.5
• Alkaline soil – pH higher than 7.5

2. By Electrical conductivity tests we come to know how many nutrients are present in the soil.

Question 3.
Write the causes of diminished soil fertility.
Answer:
Following are the causes of diminished soil fertility.

1. Soil pH less than 6 or higher than 8.
2. Low proportion of organic matter.
3. No proper drainage of water.
4. Repeated cultivation of the same crop.
5. Continuous use of saline water.
6. Excessive use of chemical fertilizers and pesticides.

Question 4.
Which crops reduce the fertility of soil and Which crops increase the fertility of soil?
Answer:
Wheat reduces the fertility of soil and leguminous crops like peanut, moong, moth bean, pea, lentil, Bengal gram, soyabean increase the fertility of soil.

Question 5.
Name and explain some useful types of soil.
Answer:
Following are some useful types of soil.

1. China clay (Kaolin): (a) It is white in colour, (b) It is used to make crockery, bathroom tiles, tanks, laboratory apparatus, masks, jars etc.
2. Shadu soil: (a) It is whitish in colour, (b) It is used for making statues and idols.
3. Terracotta soil: (a) This soil is red in colour, (b) Decorative articles and pots used for growing plants are made from this soil.
4. Multani soil: This soil is used in cosmetics.

Question 6.
Explain the types of soil on the basis of its texture.
Answer:
There are 3 types of soil on the basis of its texture.
1. Sandy soil: (a) Large particles are high in sandy soil, (b) Water drains rapidly through sandy soil, (c) It is easy to plough this soil, (d) It is less fertile because the particles of sandy soil are made of the mineral called silicon dioxide (quartz), (e) These particles do not dissolve in water and therefore the soil has very little capacity to supply dissolved nutrients.

2. Silt soil: (a) The particles of silt soil are of medium size, (b) Silt soil is not as ploughable as sandy soil but is much more ploughable than clay soil, (c) This soil contains a large proportion of organic materials, (d) Its capacity to supply nutrients is much greater, (e) Silt soil is also called sedimentary soil.

3. Clay soil: (a) The proportion of small particles is maximum, (b) The particles of clay soil feel smooth to touch, (c) Clay soil has a high water holding capacity.

Explain the given picture in your own words.

Question 1.

Answer:
1. The potato will sink in water as potato’s density is more than water.
2. This is the effect of density. The potato will float in salt solution as the density of salt solution is more than potato. The density of the water becomes greater due to the dissolved salt. That is why it is easier to swim in sea than in a well or a lake.

Can you tell?

Answer the following questions.

Question 1.
What change takes place in a balloon on filling air in it?
Answer:
On filling air in balloon, the shape of the balloon changes. Its size increases due to expansion.

Question 2.
Why is it easier to swim in the sea than in a well or a lake?
Answer:

1. Sea water is salty due to minerals in it. Whereas it is absent in well or a lake water.
2. Due to presence of salts, density of seawater is more than well or lake water, so it is easier to swim in the sea than in a well or lake.

Use your brain power!

Answer the following questions.

Question 1.
What is the effect of increased temperature on the pressure of air?
Answer:
Condition for closed environment:

1. When the temperature increases, the pressure of air also increases.
2. For example, as the air warms up, the molecules in the air become more active.
3. They use up more individual space even though there is same number of molecules. T1 s causes an increase in the air pressure.

Question 2.
Dip an uncorked inverted empty bottle in a slanting position into the water in a wide container. What do you observe?

Answer:

1. When an uncorked inverted empty bottle is kept slanting in the water container bubbling sound will be heard.
2. Air bubbles come out from the empty bottle and water enters the bottle.
3. Empty bottle is actually not empty but it is occupied by air.
4. When this air comes out, its place is taken by water. This shows that air occupies space.

Question 3.
In cold countries how do aquatic animals remain alive even after the rivers or lakes freeze in winter.
Answer:

1. Due to anomalous behaviour of water, in cold countries, water changes to ice.
2. Due to this change, its volume increases and density decreases. So ice floats on water.
3. Ice is a bad conductor of heat so it doesn’t allow heat to go inside so the water below ice remains as it is. So aquatic animals remain alive even after the rivers or lakes freeze in winter.

Question 4.
Why is it difficult to plough clay soil?
Answer:
It is difficult to plough clay soil because in clay soil the proportion of small particles is maximum. The particles of clay soil feel smooth to touch and has high water holding capacity, making it very difficult to penetrate through it.

Question 5.
Why is it easy to plough sandy soil?
Answer:

1. Sandy soil has large sized particles. It has weak structure due to less organic matter and large spaces between them.
2. The water also drains quickly through it making it dry and allows the plough to penetrate through it.

Question 6.
What is the water holding capacity of silt soil?
Answer:
Silt occurs as a deposit in riverbeds. The size of silt particles is between those of sand and clay. This soil also has humus in it which makes it the best soil to hold the right amount of water.

Question 7.
Which soil is suitable for cultivation? Why?
Answer:
The silt soil is suitable for cultivation.

1. The particles of silt soil is of medium size.
2. Silt soil is much more ploughable than clayey soil.
3. It contains large proportions of organic material.
4. This helps the soil in retention of water for a proper amount of time and makes it suitable for crops to grow.

Balbharti Maharashtra State Board Class 7 English Solutions Chapter 1.4 The King’s Choice Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 English Solutions Chapter 1.4 The King’s Choice

Class 7 English Chapter 1.4 The King’s Choice Textbook Questions and Answers

1. Write a character sketch of each of the animals. Write about their actions and thoughts and the qualities that emerge through

Question 1.
Write a character sketch of each of the animals. Write about their actions and thoughts and the qualities that emerge through
Answer:
1. Lion: Lion was big and strong and very fierce. All the other animals in the forest called him king. The king promised other animals to give them food and protection. Whenever the king roared other animals stood in awe. Whenever he took a walk, others followed him. The lion was king also very responsible. When he had his meal, he left remains for other. So they always had enough to eat.
2. Fox: He was wise and clever creature and adviser of lion king. The fox took an oath of loyalty to the king.
3. Leopard: He was watchful and swift of foot, and a body of lion king.
4. Vulture: He was bird and can fly high in sky and a messager of lion.

2. Using your imagination, write more sentences in the same pattern:
(a) But the more the lion had, the more he wanted.
(b) Whenever he took a walk, they followed him.
(c) To be king is good. But to be kind is better.

Question a.
Using your imagination, write more sentences in the same pattern:
(a) But the more the lion had, the more he wanted.
(b) Whenever he took a walk, they followed him.
(c) To be king is good. But to be kind is better.
Answer:

1. The more you quieten the mind, the more restless it becomes.
2. Whenever I speak, he interrupts me.
3. It is nice to be important. But it is more important to be nice.
4. To live well on earth is good. But to leave well is better.

3. Turn the story into a play as a group activity and present the scenes in the classroom.

Question 1.
Turn the story into a play as a group activity and present the scenes in the classroom.
Answer:
(Curtain opens) The lion is seen pacing back and forth in deep thought.

• Lion: Hmmm, I think it’s time I’ve courtiers for myself. (Calls his guards.) Tell the fox, the leopard and the vulture to meet me at once.
• Guard: Yes, Your Majesty! (Enter of fox, leopard and the vulture)
• Fox, Leopard, Vulture: Our salute to the king of kings! (all bow down)
• Lion: Mr. Fox, you are known for your wisdom. You shall be my advisor from now on.
• Mr. Fox: (elated) As you wish, Your Majesty!
• Lion: And you…. Mr. Leopard, I am impressed by your alertness. You are swift of foot too. You shall be my bodyguard.
• Mr. Leopard: (humbly) I shall be happy to serve you, Your Majesty!
• Lion: (gesturing) And dear Vulture, you fly high above. I appoint you as my messenger.
• Mr. Vulture: I am honoured, Your Majesty! (One day the vulture enters all excited)
• Mr. Vulture: O great king! I have seen a camel in the desert not far away. I think it will be a good idea for you to taste camel meat.
• Lion: (looking at his other advisers) What do you say? (Mr. Fox & Mr. Leopard not wanting to show ignorance)
• Mr. Fox & Mr. Leopard: We don’t mind. But since the vulture has suggested let him lead the way. We shall humbly follow. (All set off on a journey to the forest. It’s hot and the sun is shining brightly.)
• King: Oh! It’s too hot to bear. My paws are burning.
• Mr. Vulture: (flying high above in cooler air) Your Majesty! The desert is close by. We shall reach in some time.
• King: (not able to bear the pain) Stop! We shall return.
• Mr. Vulture: (in thought) If we return, there will be nothing for us to eat as I will not be able to eat the king. I must stop him from returning. “Your Majesty! If you want we shall rest”.
• Mr. Fox: O king! We are far away from the forest. Let us continue towards the desert.
• King: I cannot walk anymore.
• Mr. Leopard: (thinking to himself) I wish I could run away from here.
• Fox: Let me ask for help, (leaps towards the desert)
  (In the desert)…

4. This story takes an unexpected turn when the lion decides to spare the camel’s life. Choose any fable, story that you like and rewrite it giving it an unexpected turn.

Question 1.
This story takes an unexpected turn when the lion decides to spare the camel’s life. Choose any fable, story that you like and rewrite it giving it an unexpected turn.
Answer:
A ‘friend’ is a position in one’s heart and not the court. A courtier works for money. There is self-interest involved whereas a friend is a far more selfless relation in which one does not expect anything in return. It is a relationship in which friendship itself is the only reward.

5. Talk about the good qualities of any one person you do not like. (You need not name the person.)

Question 1.
Talk about the good qualities of any one person you do not like.
Answer:
I do not like my benchmate in my class as she is very untidy and comes shabbily dressed. However, there are many good qualities in her that I admire. She is an extremely polite girl. I have seen her go out of her way to help my other classmates. Also, she is very regular in her studies besides being a voracious reader. A habit that I long to imbibe in myself.

6. Language Study: Common nouns-i: Some things, animals, etc., that is, some nouns can be counted. They are called countable nouns. Some common nouns stand for something that cannot be counted. They are called uncountable nouns. Countable nouns have two forms. A noun that shows one person or thing, etc. is said to be in the singular. For example, ‘boy’, ‘girl’, ‘dog’, ‘tree’, ‘chair. A noun that shows more than one person or thing, etc. is said to be in the plural. For example, ‘boys’, ‘girls’, ‘dogs’, ‘trees’, ‘chairs’.

Note the expressions ‘a slice of bread’, ‘strands of hair’, ‘two glasses of water’, ‘a cup of milk’ and ‘a bit of fun!’. Here, we do not say ‘breads’, ‘hairs’, ‘waters’, ‘milks’, ‘funs’, etc.

Question 1.
Find five countable nouns from the passage and write their singular and plural forms.
Answer:

1. life – lives
2. friend – friends
3. messenger – messengers
4. gift – gifts
5. creature – creatures

Question 2.
List the units that we use to measure the following: water, milk, distance, weight.
Answer:

• • water – litres
  • milk – litres
  • distance – centimetre, metre, kilometre
  • weight – grams, kilograms

Class 7 English Chapter 1.4 The King’s Choice Additional Important Questions and Answers

Answer the following questions:

Question 1.
What qualities are necessary in the following? Why?
Answer:
1. King: A king should be just and kind. His justice will instill faith towards him in his subjects and his kindness will help him win their hearts. A king should not demand respect instead it should be earned with his qualities and virtues.

2. Adviser: An adviser must be very wise and foresighted. He must weigh the pros and cons of a decision and only then advise the king to go ahead with it. This is also because once the decision is taken it cannot be reverted and fate of the entire kingdom largely depends on these decisions.

3. Bodyguard: A bodyguard of a king must be his shadow. Extremely vigilant and alert, the bodyguard should be able to sense trouble and mischief as the king’s life can be in danger if he lacks these qualities. He should not hesitate to risk his life to save the king if required. This also demands physical strength and spirit.

4. Messenger: A messenger should be very quick at carrying messages as sometimes the messages are so important and urgent that any loss of time may cause great harm to the kingdom. Moreover, the messenger should be very faithful and keep the messages of the king confidential. This will safeguard the kingdom from enemies. Also, the messenger should remember that he represents the king himself, hence should be very trustworthy.

Question 2.
Write the oath that each of the courtier must have taken.
Answer:
1. Oath taken by the advisor (Fox):
I, Mr. Fox, do hereby solemnly swear that I will remain loyal to my king and the kingdom and to the best of my ability advise the king on matters of administration in order to preserve, protect and defend the kingdom.

2. Oath taken by the messenger (Vulture):
I, Mr. Vulture, do hereby solemnly swear that I will remain loyal to my king and this great kingdom and will to the best of my ability deliver messages as and when required. In doing so I shall not alter the messages, keeping them confidential in the best interest of my kingdom in order to preserve, protect and defend it.

3. Oath taken by the bodyguard (Leopard):
I, Mr. Leopard, do hereby solemnly swear that I shall always be with the king like his shadow and will to the best of my ability protect, guard and defend the king and in doing so with loyalty I shall not hesitate to lay down my life in the general good of my beloved land.

Question 3.
Why was the vulture told to lead the way?
Answer:
The vulture had suggested that the lion should eat the camel it had seen in the desert. As, neither the lion nor the fox, nor the leopard had ever seen a camel and besides, as the fox and leopard didn’t want the vulture to appear wiser than them, they asked the vulture to lead as it was his idea.

Question 4.
Why had the lion never seen a camel?
Answer:
The lion stayed in the forest and a camel lives in a desert. So the lion had never seen a camel.

Question 5.
What advice did the fox and the leopard give? Was it based on good and sound thinking?
Answer:
The fox and the leopard advised the king to set off on a camel hunt. This advice was not based on good and sound thinking as they were accustomed to walking in the forest under shady trees and the desert would not provide them this comfort. They didn’t want to appear foolish and ignorant and so the advice.

Question 6.
Do you think the vulture was enjoying the search?
Answer:
Yes, as the vulture was flying high up in the cooler air, it was enjoying the search.

Question 7.
Do you think the king’s decision to go back was right?
Answer:
No, I don’t think the king’s decision to go back was right as he had already walked a long distance not only risking his life but that of his courtiers as well. He could have rested and then continued.

Question 8.
Can you guess the plan the fox had thought of?
Answer:
The fox had planned to trick the camel, and use him as a means of transport to go to their forest, kill him and have a feast.

Question 9.
Why does the fox address the camel as friend camel?
Answer:
The fox addressed the camel as ‘friend camel’ to make him believe that he is his well-wisher so that the camel does not see through his wicked intentions.

Question 10.
What qualities of the courtiers emerge in this part of the story when they were in the desert?
Answer:
The lion king comes across as someone who had leapt before looking what he was landing into. He himself didn’t know how he would return to the forest but commanded that they should stop right there. Not a very thoughtful and far sighted king. The vulture appears to be self-centred and greedy. He was only interested in eating the camel. The leopard, though a bodyguard, was a coward who wanted to run away. However, the fox comes across as a problem-solver who rescues everyone from the situation with his wit.

Question 11.
The fox, the leopard and the vulture have the same thought about the camel. Why is it so?
Answer:
By sparing the camel and not eating it, the king had spoilt the plan of the fox, vulture and the leopard. As they had similar interests, they had the same thought about the camel. The animals were all tired and hungry and realised that the camel would make a large meal. The camel being simple minded would not suspect this play and they could easily have a feast and satiate their hunger by fooling him. They were now irritated with their plans having been failed.

Question 12.
Did you expect the lion to be kind to the camel? Do you think his decision was right?
Answer:
No, I didn’t expect the lion to be kind to the camel who was his prey. Yes, I think the lion’s decision was right as he was thankful to the camel for saving their lives by carrying them back to the forest. His decision was a mark of gratitude towards the camel.

Answer in one sentence.

Question 1.
Why did the king appoint the leopard as his bodyguard?
Answer:
The king appointed the leopard as his bodyguard as he was watchful and swift on his feet.

Question 2.
What did the lion’s courtiers do when he went hunting?
Answer:
When the lion king went hunting, the courtiers found animals for him to kill.

Question 3.
How does the vulture describe the camel to the lion king?
Answer:
The vulture describes the camel as a lone animal in the desert who was big and fat.

Question 4.
Why couldn’t the lion walk any further?
Answer:
The lion could not walk any further as the hot sand had burned his paws.

Question 5.
What does the fox tell the camel?
Answer:
The fox tells that the camel that the lion king had killed his master and it was now free. The lion king, therefore, had invited it to live at his court.

Question 6.
On what condition did the camel agree to serve the lion?
Answer:
The camel agreed to serve the lion in return for a home at his court.

Question 7.
Why were the courtiers shocked to listen to the lion king’s decision?
Answer:
The courtiers were shocked to listen to the lion king’s decision as they had risked their lives to eat the camel’s meat but the king had now decided to spare it.

Reading Skills, Vocabulary and Grammar

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
Complete the web
Answer:

Question 2.
Who said to whom
Question i.
“A king must have a court”
Answer:
The king thought to himself.

Question ii.
“I want you to be my adviser”
Answer:
The king said the above sentence to the fox.

Question iii.
“I want you to be my bodyguard”
Answer:
The king said the above sentence to the leopard.

Question iv.
“You are to be my messenger”
Answer:
The king said the above sentence to the vulture.

Complex Factual Questions:

Question 1.
Why must a king have a court?
Answer:
A king must have a court for the smooth functioning of his kingdom. Besides, the king cannot do everything on his own so, by delegating work to his courtiers, the king can assure that various departments in his kingdom are serving his subjects well.

Question 2.
How is the human administration similar to that of what we read in the passage?
Answer:
Just as we have different portfolios the Lion king also gave responsibilities to his courtiers. For example the fox who is very wise and clever and we too have a council of ministers who advice the Prime Minister; just like the leopard who is watchful and swift, we too have the defence system in our country and like their vulture who is a messenger we too have the ministry of communication and technology.

Question 3.
What is the oath of loyalty?
Answer:
An oath of loyalty is a pledge one takes acknowledging one’s duty and faithfulness towards one’s country or a king.

Vocabulary:

Question 1.
Give the meanings of the following words.
Answer:

• courtiers – people who attend the royal court
• adviser – the one who advises
• bodyguard – a person employed to protect somebody
• loyal – faithful towards a person or an organisation.

Grammar:

Question 1.
Pick out the Subject and Predicate from the following sentences.
1. They brought him gifts from every corner of the forest.
2. The lion called a leopard to his side.
3. The fox, the vulture and the leopard took an oath of loyalty to the king.
4. The three courtiers never opposed the king.
Answer:

Subject	Predicate
1. They	brought him gifts from every corner of the forest.
2. The lion	called a leopard to his side.
3. The fox, the vulture and the leopard	took an oath of loyalty to the king.
4. The three courtiers	never opposed the king.

Question 2.
Identify any 4 common nouns from the above passage.
Answer:
king, forest, fox, leopard, animals

Question 3.
Add the question tag for the following sentences.

1. He called a fox to his side.
2. You are to be my messenger.
3. The king promised to give them food and protection.
4. He was big and strong and very fierce.

Answer:

1. He called a fox to his side, didn’t he?
2. You are to be my messenger, aren’t you?
3. The king promised to give them food and protection, didn’t he?
4. He was big and strong and very fierce, wasn’t he?

Question 4.
Give the adjective forms for the following.

1. protection
2. loyalty
3. watch
4. thought

Answer:

1. protective, protected
2. loyal
3. watchful
4. thoughtful

Question 5.
Complete the table using the singular or plural forms of the nouns.
Answer:

Singular	Plural
1. apple	apples
2. book	books
3. class	classes
4. photo	photos
5. life	lives
6. woman	women
7. mouse	mice
8. child	children
9. deer	deer
10. country	countries

Question 6.
Find five countable nouns from the passage and write their singular and plural forms.
Answer:

Singular	Plural
1. king	kings
2. animal	animals
3. gift	gifts
4. fox	foxes
5. bird	birds

Read the following passage and do the activities.

Simple Factual Questions:

Question 1.
State whether the following statements are true or false.
1. The lion ordered his courtiers to eat the camel.
2. The vulture, fox and the leopard offer themselves to the lion king.
Answer:
1. False
2. True

Complex Factual Questions:

Question 1.
Were the courtiers being loyal to their king?
Answer:
No, the courtiers were not being loyal to their king as by getting the camel killed by the lion they would force the lion king to go against his own promise of protecting the camel thereby spoiling the king’s image.

Question 2.
What qualities of the camel are seen in his speech?
Answer:
The camel comes across as very humble and loyal character. He knows very well that he could not be of much use to the lion in the forest. Moreover, he is willing to lay down his life for the sake of his king which means that he is extremely selfless.

Question 3.
Why did the lion laugh to see the courtiers go?
Answer:
The lion laughed to see the courtiers go because he knew they were unfaithful courtiers and were only with him to serve their own selfish motives. He had been successful in driving them away without pronouncing a cruel judgment against them.

Question 4.
Why did the king offer his friendship to the camel?
Answer:
The king realized that his courtiers were unfaithful. In contrast, the camel was loyal and good. So, he offered friendship to the camel.

Question 5.
Explain the lines “To be king is good. But to be kind is better”.
Answer:
The king through the lines “To be king is good, but to be kind is better” wants to say that as a king he demanded respect but couldn’t win loyal friends or courtiers. But by being kind to the camel he not only gained respect but also won a true friend.

Vocabulary:

Question
Give homophones for the following words.
(a) accept
(b) seen
Answer:
(a) except
(b) scene

Grammar:

Question 2.
Away flew the vulture.
(Separate the subject and predicate.)
Answer:
The vulture – subject, flew away – predicate

Question 3.
They were never seen in the forest again.
(Add a question tag)
Answer:
They were never seen in the forest again, were they?

Question 4.
What qualities of the lion king impresses you the most? Why?
Answer:
The lion king was very witty and wise. He had the skill of teaching his wicked and cunning courtiers a lesson without being cruel to them. He also had the quality of distinguishing between the faithful and the unfaithful. These qualities of the lion king impress me the most.

Language Study:

Do as directed.

Question 1.
The king promised to give them food and protection. (Rewrite using ‘Not only… but also’.)
Answer:
The king promised to give them not only food but also protection. The king not only promised to give them food, but also protection.

Question 2.
Let us go back to the forest.
(State the kind of sentence.)
Answer:
Imperative sentence.

Question 3.
They did not want the vulture to seem wiser than them. (Iden tify the degree of comparison.)
Answer:
Comparative degree.

Question 4.
All the other animals in the forest called him king.
(Rewrite beginning with ‘He was’.)
Answer:
He was called king by all the other animals in the forest.

Question 5.
“Our king, the lion, has killed your master” said the fox.
(Change into indirect speech.)
Answer:
The fox informed that their king, the lion, had killed his master.

Question 6.
Make sentences using phrases/idioms.
Answer:

• To set off – We packed our bags and set off on a nature trail.
• To keep (yourself) from – My grandmother is 70 years old. But that does not keep her from enjoying treks.

Question 7.
Complete the table.
Answer:

Noun	Verb	Adjective
friendship	befriend	friendly
life	live	lively
thought	think	thoughtful
protection	protect	protective
strength	strengthen	strong

Writing Skills:

Question 1.
Choose any fable, story that you like and rewrite it giving it an unexpected turn.
Answer:
The Thirsts Crow
One hot day, a thirsty crow flew all across the plains in search of water. It had taken him more time than he thought and he felt weak. Losing all hope, he flew down to see if there was water kept outside the houses by the lonely street.

To his delight, he found a jug with water outside a small hut. But, the jug had very little water and it’s neck was too narrow for his head to be put in. He tried picking up the jug but in vain. Finally, he saw some pebbles and decided that if he dropped the pebbles, into the jug the water level would rise and he would be able to quench his thirst. But the crow had no patience to throw each pebble in one by one and wait for water level to rise slowly.

He saw a big stone lying by the side of the jug. He thought to himself, “if I put this big stone inside the jug, the level of water will rise at once”.

In his heart he felt proud about himself for this brilliant idea. So in desperation, he took the big stone and threw it in the jug. But to his disappointment, the stone hit the base of the earthen jug so hard that the jug broke into pieces. All the water from the jug spread all over the place. The crow tried to drink but before he could do so the thirsty earth had soaked in most of it.
Moral: Haste makes waste.

The King’s Choice Summary in English

The folk tale ‘The King’s Choice’ highlights the importance of virtues such as loyalty and kindness. The lion king in the story proves that a king’s might and majesty may win him some untrue and fake followers but kindness alone can give him the gift of faithful friends. On the other hand, the faithful camel’s character underlines the age old maxim, ‘Loyalty always pays’.

Paraphrase:

The story takes us to a forest where the lion king appoints the fox, the vulture and the leopard as his courtiers. However, the vulture due to his selfish and greedy motive of eating up the lion king lures him into going to the desert to eat camel meat. Other courtiers also follow.

When the king and his companions get tired of walking in the scorching sun, the fox comes to their rescue. He, through his wit and craftiness, befriends the camel and tricks him into believing that the king wanted to befriend him. The innocent camel appears before the king and carries the trio back to the forest on his back.

Filled with gratitude towards the camel on saving his life, the king decides to spare him and gives him his protection. Although the three courtiers are unhappy with the decision, they keep quiet.

However, after few days, unable to go hunting, the lion summons his courtiers and orders them to bring him food. The cunning fox once again holds a meeting and they plan to compel the king to eat the camel. But there is a twist in the story, the camel is safe once again due to its loyalty and the betrayers are compelled to flee. Thus, the king outsmarts his crafty and unfaithful courtiers and repays the camel for his loyalty with his kindness.

Glossary:

1. fierce (adj) – physically violent and frightening
2. swift (adj) – quick
3. watchful (adj) – alert and vigilant
4. oath (n) – promise or vow
5. awe (n) – respect and fear
6. remains (n) – the parts left over after other parts have been removed
7. lone (adj) – only one
8. vulture (n) – a large bird of prey
9. paws (n) – an animal’s foot
10. feast (n) – a large meal, typically eaten during celebrations
11. risked (v) – put in danger
12. grateful (adj) – thankful

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 12 The Muscular System and Digestive System in Human Beings Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 12 The Muscular System and Digestive System in Human Beings

Class 7 Science Chapter 12 The Muscular System and Digestive System in Human Beings Textbook Questions and Answers

1. Fill in the blanks with the right word from the brackets:

Question a.
The process of digestion starts from the ………….. (stomach, mouth).
Answer:
mouth

Question b.
Eyelids have …………… muscles. (voluntary, involuntary)
Answer:
involuntary

Question c.
……………. is not a function of muscular system. (production of blood cell, performing movement)
Answer:
Production of blood cells

Question d.
Muscles of the heart are …………….. . (ordinary muscles, cardiac muscles)
Answer:
cardiac muscles

Question e.
Pushing forward the food that has been chewed is the function of the …………… . (stomach, oesophagus)
Answer:
Oesophagus.

2. Find a match for me.

Question a.

Column ‘A’	Column B’
1. Cardiac muscle	a. Always functions in pairs
2. Are brought about by muscle	b. We never feel tired
3. Pepsin	c. Uncontrolled and painful contraction of muscles
4. Cramps	d. Chewing movement of the jaw
5. Skeletal muscles	e. Enzymes of the gastric juice

3. Who is telling a lie?

Question a.

Organ	Statement
1. Tongue	a. My taste buds can tell only a sweet taste.
2. Liver	b. I am the largest gland in the body.
3. Large intestine	c. I am 7.5 metre long.
4. Appendix	d. Digestion is impossible without me
5. Lung	e. I play an important role in excretion.

Answer:

1. Lie. My taste buds can tell all tastes – sweet sour, bitter.
2. Truth.
3. Lie. It is 1.5 metre long.
4. Truth.
5. Lung → Lie. It plays important role in breathing.

4. Give reasons.

Question 1.
Food becomes acidic in the stomach.
Answer:

1. The gastric glands of stomach secrete gastric juice.
2. Food that has entered stomach is churned.
3. Three components of gastric juice namely hydrochloric acid, pepsin and mucus are mixed with food here and the food becomes acidic.

Question 2.
Cardiac muscles are said to be involuntary muscles.
Answer:

1. Cardiac muscles are found in the heart.
2. These muscles bring about the contraction and relaxation (beating) of the heart.
3. Their movement is involuntary.
4. Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute. They do not depend upon our will.
5. Beating is carried out in their own fixed manner.

So cardiac muscles are said to be involuntary muscles.

Question 3.
Intoxicating substances should not be consumed.
Answer:

1. Physical health is important for our organ system to function properly.
2. But harmful habits like smoking, chewing of tobacco, drinking alcohol affect our health adversely.
3. If we consume any tobacco products, the mouth, pharynx, alimentary canal, and other organs of the digestive system cannot function properly.
4. It causes problems like vomiting, nausea, and headache.
5. Tobacco particles stick to teeth, gums, and skin of the mouth cavity and slowly cause injury to those parts resulting in their dysfunction.
6. This causes swelling of the gums and pain when moving the jaws.
7. The pharynx and intestine become inflamed it progress into cancer leading to death.

Question 4.
Your muscles should be strong and efficient.
Answer:
Muscles are bundles of fibres that can contract and relax as required.

1. The action of muscles is necessary for all kinds of movements from the small movements of eyelid to those that demand great strength when chopping wood with an axe.
2. We use muscles for various movements like talking laughing, walking, jumping, throwing etc.
3. Therefore our muscles should be strong and efficient to do our day today work well and smooth functioning of life processes.

5. Answer the following. 

Question a.
How many types of muscles are there? Which are those types?
Answer:
Muscles are bundles of fibres that can contract and relax as required. There are three types of muscles.

• Skeletal muscles.
• Heart or cardiac muscles.
• Smooth muscles.

1. Skeletal muscles: (a) Skeletal muscles work with bones, the two ends of each of these muscles are attached to two different bones. (b) They are responsible for holding the bones of the skeleton together and giving shape to our body, (c) Skeletal muscles permits movement of t the body and maintain the posture of the body. (d) Skeletal muscle is voluntary e.g. muscles in our arms and legs are voluntary muscles, their action depends upon our will. That’s why they are called voluntary muscles.

2. Heart or cardiac muscles: (a) Heart or cardiac muscles bring about the contraction and relaxation (beating) of the heart. (b) Their movement is involuntary, (c) Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute, (d) Cardiac muscle is found in heart.

3. Smooth muscles: (a) These muscles are present in the internal organs other than the heart, e.g. muscles of the stomach, intestine, blood vessels, uterus etc. (b)Their movements are involuntary and slow, (c) They are not according to our will. (d) Various vital functions of our body such as digestion, respiration and movement of food material of which we remain quite unaware, are carried out by these special muscles.

Question b.
What causes the problem of acidity? What is its effect on the body?
Answer:

1. Stress is the main cause of acidity.
2. Hectic lifestyle and stress can lead to unhealthy or irregular meals, not good for digestion process, and this may cause acidity.
3. Other reasons are eating spicy food, drinking too much alcohol, missing meals, an empty stomach may lead to acidity.
4. Acidity leads to stomach upset, burning sensation in chest and stomach, constriction of blood vessels, weight gain, obesity, cardiovascular damage.

Question c.
Name the different types of teeth. What is the function of each type?
Answer:
There are four types of teeth, namely incisors, canines, pre-molars, and molars.
Each tooth is covered by a hard substance called enamel. Enamel is made up of calcium salt.
The process of digestion begins with the function of the teeth in the mouth.
1. Incisors: (a) These come in first 6-months of age. Incisors are the eight teeth in the front and centre four on top and four on bottom, (b) They are sharp and blade like for cutting food. e.g. for biting an apple, (c) We use them to take first bite of food.

2. Canines: (a) These are strong and pointed, sharpest of all for tearing food. e.g. to tear off a piece of tough meat, (b) They play important role in digestion of food, (c) They appear between 11 and 20 months of age.

3. Pre-molar: Pre molar share features of both canines and molars. (a) You can use them for grinding and chewing food. So that it becomes semi-liquid helping to gulp down the throat easily, (b) They are situated at each side of your mouth in deep settings, (c) They appear at the age of 10 years.

4. Molar: (a) These are broad and flat on top for crushing and grinding food. e.g. to grind up nutmeats. (b) Two teeth above and two teeth below, they appear at the age 11-13 years. (c) Molars are more prone to germ attack because of their remote location in our mouth.
So we should keep them clean.

6. Sketch and label a diagram of the digestive system and describe it in your own words.

Question a.
Sketch and label a diagram of the digestive system and describe it in your own words.
Answer:

1. Conversion of food into a soluble form and its absorption into the blood is called digestion.
2. The digestive system consists of the alimentary canal and digestive glands.
3. The total length of alimentary canal is about 9 metres.
4. Its main parts are the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
5. The salivary glands, liver, pancreas are the digestive glands connected to the alimentary canal.
6. Different organs of the digestive system perform the function of digestion.
7. There are different stages in the process of digestion of food.
8. The process of digestion begins with the function of the teeth in the mouth, food is chewed into small pieces.
9. There are four types of teeth, incisors, canines, pre-molars and molars.
10. Saliva in the mouth contains enzymes, ptyalin, or amylase. It converts starch into maltose.

a. Oesophagus:

1. It is a tube leading from the pharynx to the stomach,
2. It pushes the food towards the stomach.

b. Stomach:

1. The large sac like part of the alimentary canal is called the stomach.
2. Food that has entered is churned.
3. The gastric glands of stomach secrete gastric juice which contain hydrochloric acid, pepsin and mucus.
4. They mix with food and food becomes acidic.
5. Mainly proteins are digested in stomach.
6. Due to the churning and actions of gastric juice, food become a semi-solid slurry which is pushed into the small intestine.

c. Small intestine: (6m long)

1. Bile secreted by liver mixes with food in small intestine,
2. Most of the digestion and absorption of food takes place here.

d. Large intestine: (1.5m long) only water is absorbed in the large intestine. Undigested remain is thrown out of the body through the anus.

Project:

Question 1.
Make charts about maintaining good health.

Question 2.
Design a power point presentation about the digestive system and present it in the class.

Class 7 Science Chapter 12 The Muscular System and Digestive System in Human Beings Important Questions and Answers

Choose and write the correct word.

Question 1.
The structure that connects bones to the muscles is the ………………….. .
(a) ligament
(b) tendon
(c) fascicle
(d) skin
Answer:
(b) tendon

Question 2.
………………….. is not performed by muscles.
(a) Motion
(b) Excretion
(c) Maintenance of posture
(d) Heat production
Answer:
(d) Heat production

Question 3.
Approximately ………………….. skeletal muscles are there in the human body.
(a) 1000
(b) 600
(c) 100
(d) 60
Answer:
(b) 600

Question 4.
Most of the fat digestion occurs in ………………….. .
(a) rectum
(b) stomach
(c) small intestine
(d) large intestine
Answer:
(c) small intestine

Question 5.
Protein digestion is accomplished in ………………….. .
(a) stomach
(b) ileum
(c) rectum
(d) duodenum
Answer:
(b) ileum

Question 6.
The main function of the muscular system is ………………….. .
(a) excretion
(b) digestion
(c)movement
(d) contraction
Answer:
(c)movement

Question 7.
The largest muscle of our body is in the ………………….. .
(a) arm
(b) face
(c) thigh
(d) None
Answer:
(c) thigh

State whether True or False. Correct the false statement and rewrite:

Question 1.
Saliva is mixed with food in the mouth.
Answer:
True.

Question 2.
Gastric juice makes food alkaline.
Answer:
False. Gastric juice makes food acidic.

Question 3.
Pancreas is the largest gland in the body.
Answer:
False. Liver is the largest gland in the body.

Question 4.
Food becomes acidic in stomach.
Answer:
True

Question 5.
Cardiac muscles are said to be voluntary muscles.
Answer:
False. Cardiac muscles are involuntary.

Question 6.
Muscles contribute 60% of the weight of a healthy adult human body.
Answer:
False. Muscles contribute almost 40% of the weight of a healthy adult human body.

Question 7.
There are about 30 muscles in the human face.
Answer:
True

Question 8.
Muscles in our arms and legs have involuntary muscles.
Answer:
False. Muscles in our arm and legs are voluntary muscles.

Question 9.
Functions of organs like stomach, intestine, heart are carried out by voluntary muscles.
Answer:
False. Functions of these organs are carried out by involuntary muscles.

Question 10.
Smooth muscles are involuntary muscles.
Answer:
True.

Question 11.
The digestive function of the liver is to produce bile.
Answer:
True.

Question 12.
The muscular tissue has the ability to contract or shorten.
Answer:
True.

Find a match for me.

Question 1.

Column A’	Column B’
1. Salivary gland	a. Making food acidic
2. Liver	b. Regulation of sugar level
3. Pancreas	c. Digestion of carbohydrates
4. Stomach	d. Digestion of protein, fats, carbohydrate

Answer:

Column A’	Column B’
1. Salivary gland	c. Digestion of carbohydrates
2. Liver	d. Digestion of protein, fats, carbohydrate
3. Pancreas	b. Regulation of sugar level
4. Stomach	a. Making food acidic

Question 2.

Column ‘A’	Column B’
1. Saliva	a. Gastric juice
2. Juice in mouth	b. Bile
3. Juice produced by stomach	c. Ptyalin
4. Juice stored by gall bladder	d. Lubricates food

Answer:

Column ‘A’	Column B’
1. Saliva	d. Lubricates food
2. Juice in mouth	c. Ptyalin
3. Juice produced by stomach	a. Gastric juice
4. Juice stored by gall bladder	b. Bile

Question 4.

Column ‘A’	Column B’
1. Cardiac muscle	a. Inside of organs like stomach
2. Skeletal muscle	b. Found in heart
3. Smooth muscle	c. Attached to bones

Answer:

Column ‘A’	Column B’
1. Cardiac muscle	b. Found in heart
2. Skeletal muscle	c. Attached to bones
3. Smooth muscle	a. Inside of organs like stomach

Find the odd man out:

Question 1.
Stomach, esophagus, liver, small intestine, rectum
Answer:
Liver which is a gland and others are parts of digestive tract.

Question 2.
Saliva, bile, pancreatic juice, gastric juice chyme
Answer:
Chyme, it is a liquid food others are digestive juices.

Name the following:

Question 1.
Gastric juices in stomach
Answer:
Hydrochloric acid, Pepsin, Mucus.

Question 2.
Juices secreted by liver
Answer:
Bile.

Question 3.
Pancreatic juices.
Answer:
Trypsin, Lipase, Amylase.

Question 4.
Salivary gland secretion.
Answer:
Saliva

Question 5.
Enzyme present in saliva.
Answer:
Ptyalin or Amylase.

Question 6.
Types of muscles.
Answer:
Skeletal, Cardiac and Smooth muscles.

Question 7.
Study of muscles.
Answer:
Myology

Give scientific reason:

Question 1.
Skeletal muscles give shape to our body.
Answer:

1. Skeletal muscles are voluntary muscles. The two ends of each of these muscles are attached to two different bones.
2. Muscles of the arms and legs are skeletal muscles.
3. They are responsible for holding the bones of the skeleton together and giving shape to our body.

Question 2.
The process of digestion begins in the mouth.
Answer:

1. The process of digestion begins with the function of the teeth.
2. There are 4 types of teeth – incisors, canines, pre-molar, and molar.
3. They are responsible for grinding the food.
4. Saliva present in the mouth mixes with the food and makes it soft.
5. An enzyme present in saliva called ptyalin amylase converts starch into maltose. Thus, the process of digestion begins in the mouth.

Question 3.
Metabolic processes are impossible without enzymes.
Answer:

1. Enzymes are substances secreted’ in the body of an organism which bring about specific chemical reactions.
2. Enzymes are specific type of proteins. They are most active at normal body temperature.
3. Digestion enzymes of the digestive system bring about changes in the food material.
4. Food is digested with the help of enzymes and converted into more soluble and simple form.

Write short notes on:

Question 1.
Voluntary muscles
Answer:

1. Working with our hands, walking, eating are functions that depend upon our will.
2. Muscles used in these actions are called voluntary muscles, e.g. skeletal muscles are voluntary muscles.

Question 2.
Involuntary muscles
Answer:

1. Various processes like breathing, blood circulation, digestion are vital function, essential for life.
2. They do not depend upon our will.
3. The muscles of organs which carry out these involuntary functions are called involuntary muscles.
4. Functions of organs like the stomach, intestine, heart are carried out in their own fixed manner by involuntary muscles, e.g. cardiac muscle present in heart, smooth muscles in lining of stomach, small intestine, blood vessel, uterus.

Question 3.
Muscle and its types
Answer:
There are three types of muscles in body

1. Skeletal Muscles
2. Cardiac Muscles
3. Smooth Muscles

Question 4.
Digestive glands
Answer:
The salivary glands, liver and pancreas are the digestive glands connected to the alimentary canal.
1. Salivary glands: (a) Saliva is produced in the salivary glands in the mouth cavity, located in front of the ears, below the tongue, (b) It is carried to the mouth via ducts, (c) It is mixed with food during the process of chewing.

2. Saliva: contains an enzyme called Ptyalin or salivary amylase. Ptyalin convdrtfe starch into a sugar called maltose.

3. Liver: (a) The liver is the largest gland in the body, (b) Main function is storage of glucose, (c) The digestive juice secreted by the liver is bile, (d) Bile is carried into small intestine, it mixes with food and helps in digestion of fats.

4. Pancreas: The pancreas secretes the pancreatic juice that contains various enzymes

• Trypsin → converts proteins into amino acids.
• Lipase → converts fats into fatty acids, glycerol
• Amylase → converts complex carbohydrate into simple sugar

Question 5.
Enzymes
Answer:
Enzymes are substances secreted in the body an organism which bring about specific chemical reactions.

1. Metabolic processes are impossible without enzymes.
2. Digestive exzymes of the digestive system bring about changes in the find material.
3. They break down the food into simple form.
4. They are a type of protein.
5. Saliva contain pytalin which converts starch into maltose.
   • Trypsin: Convert proteins into amino acids.
   • Lipase: Convert fats into fatty acid.
   • Amylase: Converts complex carbohydrates into simple sugar.

Question 6.
Draw the structure of the different layers of the tooth.
Answer:

Differentiate between:

Question 1.
Voluntary and Involuntary muscles.
Answer:

Voluntary muscle	Involuntary muscle
1. Voluntary muscle means you can control it consciously.	1. Involuntary muscles are controlled by your subconscious. You have no control over them.
2. Skeletal muscles are voluntary muscles.	2. Cardiac muscles and smooth muscles are involuntary muscles.
3. Muscles in our arms and legs are voluntary muscles.	3. Muscles in heart, stomach, blood vessel, intestine are involuntary muscles.

Question 2.
Skeletal muscle and Cardiac muscle.
Answer:

Skeletal muscle	Cardiac muscle
1. Skeletal muscles are voluntary muscles.	1. Cardiac muscles are involuntary muscles.
2. Muscles in our arms and legs are voluntary muscles.	2. Muscles in heart, stomach, blood vessel, intestine are involuntary muscles.
3. They hold bones of the skeleton together and gives shapes to our body.	3. They bring about contraction and relaxation of heart.

Answer the following:

Question 1.
What is meant by organ system?
Answer:

1. There are different structural organizational levels in living organism.
2. Cells → tissues → organ → organ system → organism
3. Different organs together form one organ system.

Question 2.
How are the bones in our body joined to each other?
Answer:
Skeleted muscles join two bones with the help of tendons.

Can you tell?

Answer the following questions:

Question 1.
What is the mutual relationship between muscles and bones?
Answer:

1. Muscles are firmly attached to bones by means of tendons.
2. When muscles contract there is movement at the joint and there is pull on tendon which in turn pull on the bones to which they are attached.

Question 2.
Are the muscles of the different organs in our body identical?
Answer:
No, muscles of the different organs are not identical, some are voluntary, some are involuntary.

Question 3.
How do muscles perform their functions?
Answer:

1. Muscles in our body always work in groups.
2. When some muscles contract other muscles of the same group relax.
3. This is how muscles help in proper performance of the various functions of own body.

Answer the following questions:

Question 1.
Which parts of our body are made up only of muscles?
Answer:
Tongue, heart, stomach, liver, pancreas, intestines are made up of only muscles.

Question 2.
What would happen if the cardiac muscles do not move?
Answer:

1. Cardiac muscles cause our heart to relax and contract continuously at a rate of about 70 times per minute.
2. These muscles bring about the contraction and relaxation (beating) of the heart.
3. If the cardiac muscles do not move, heart will stop beating, and will not pump blood to other parts of the body and person will die.

Question 3.
Food enters the stomach and the stomach muscles do not move.
Answer:

1. Smooth muscles are present in the lining of stomach.
2. Their movement is responsible for churning of food.
3. If the muscles do not move, food will not be digested.

Question 4.
During digestion does all the food that we have eaten get converted into useful nutritive substances?
Answer:

1. During digestion not all the food is converted into useful nutritive substance, only whatever nutrients we obtain by digestion of food gets absorbed into the blood in small intestine.
2. Undigested remains of the food enters the large intestine and thrown out of the body through the anus.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 8 Static Electricity Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 8 Static Electricity

Class 7 Science Chapter 8 Static Electricity Textbook Questions and Answers

1. Choose the correct option and fill in the blanks.
(always repulsion, always attraction, displacement of negative charge, displacement of positive charge, atom, molecule, steel, copper, plastic, inflated balloon, charged object, gold)

Question a.
There is ………….. between like charges.
Answer:
always repulsion

Question b.
…………. is responsible for generation of electric charge in an object.
Answer:
displacement of negative charge

Question c.
A lightning conductor is made of a ……………… strip.
Answer:
copper

Question d.
……………… does not get electrically charged easily by rubbing.
Answer:
Steel

Question e.
There is …………………. when opposite electric charges come near each other.
Answer:
always attraction

Question f.
A ……………… canbe detected with an electroscope.
Answer:
charged object

2. Explain why it is not safe to go out with an umbrella when there is heavy raine lightning or thunder.

Question a.
Explain why it is not safe to go out with an umbrella when there is heavy raine lightning or thunder.
Answer:
Large amount of charges get built up in the clouds in rainy and stormy weather.

1. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
2. Wire of umbrella is made up of metal and cloth is made up of synthetic material.
3. If lightning strikes, then umbrella catches it and there are chances of fire and it would be dangerous.
4. So it is not safe to go out with an umbrella when there is heavy rain.

3. Answer in your own words.

Question a.
How will you protect yourself from lightning?
Answer:

1. To protect from the lightning, we have to put lightning conductor on high rise buildings,
2. we should not stand under a tree in rainy and stormy weather.
3. We should not go out with an umbrella in heavy rain, lightning or thunder.

Question b.
How are charges generated?
Answer:

1. Friction causes a charge to develop, because on rubbing, some negative particles are transferred from one substance to the other and the later develops a negative charge.
2. The substance from which particles are removed lose negative charge and hence, it develops a positive charge.

Question c.
In the lightning conductor, what provision is made for spreading the electricity into the ground?
Answer:

1. The lightning conductor, consists of a long i copper strip with one end forked. This end is ‘ at the highest part of the building.
2. The other end of the strip is connected to a plate of cast iron.
3. A pit is dug in the ground, coal and salt are filled into the pit and the iron plate is placed upright in the pit.
4. There is also a provision for pouring water into it.
5. This helps to spread the electric charge quickly into the ground.

Question d.
Why do farmers stick an iron staff into the ground while working in the field in rainy conditions?
Answer:

1. Large amount of charges get built up in the clouds in rainy and stormy weather.
2. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
3. Due to iron staff, the charges will be conducted to the earth through iron metal and spread quickly into the ground.
4. This way farmers are saved from lighting strike.

Question e.
Why is lightning not seen every day during the rainy season?
Answer:

1. When air and clouds rub against each other in the sky the upper part of some clouds becomes positively charged and the lower side become negatively charged.
2. When this negative charge at the bottom of the cloud becomes much larger than the charge on the ground, it starts flowing towards the ground in stages, but this doesn’t happen every day. So lightning is not seen every day during the rainy season.

4. What are the characteristics of a static electric charge?

Question a.
What are the characteristics of a static electric charge?
Answer:
Following are the characteristics of a static electric charge.

1. The electric charge generated by friction is called frictional electricity. This charge is produced only at the place of friction, hence it is called static electricity.
2. It remains on the object for a short duration.
3. The charges of static electricity are absorbed in moist air.
4. An electrically charged object attracts another object which has no electric charge.
5. Like charges repel each other.
6. Unlike charges attract each other.
7. Repulsion is the sure test of the existence of a static charge.

5. What is the damage caused by lightning? How will you ereate awareness to prevent it?

Question a.
What is the damage caused by lightning? How will you ereate awareness to prevent it?
Answer:
Due to lightning great damage can occur.

1. It may cause fire.
2. Person on whom lightning strikes may die also.
3. It causes more temperature than sun.

Awareness to prevent it:

1. Guide the people to install lightning conductor on tall buildings.
2. Do not stand on open ground, below a tree, or on a high location during the thunder storms.
3. Do not use plugged in electrical appliances.
4. Do not stand near an electric pole, telephone pole or a tower.
5. Stay in pucca house made of brick and cement.
6. Stand on only wood, a plastic sheet or sack of jute.

Project:

Question a.
Make an electroscope yourself by using a thin aluminium foil and check which substances become electrically charged.

Class 7 Science Chapter 8 Static Electricity Important Questions and Answers

1. Choose the correct option and fill in the blanks.
(always repulsion, always attraction, displacement of negative charge, displacement of positive charge, atom, molecule, steel, copper, plastic, inflated balloon, charged object, gold)

Question 1.
named the electric charges as positive charge and negative charge.
Answer:
Benjamin Franklin

Question 2.
Each atom contains a stationary charge and moving charges.
Answer:
positive, negative

Question 3.
Each atom is electrically
Answer:
neutral

Question 4.
Amber is called in the Greek language.
Answer:
electron

Question 5.
The charges of electricity are absorbed in moist air.
Answer:
static

Question 6.
Electrically charged objects uncharged objects.
Answer:
attract

Question 7.
is used as a test for identifying an electrically charged object.
Answer:
Repulsion

Question 8.
The property of amber to attract things was named electricity by in 1646 AD.
Answer:
Thomas Brown

Question 9.
The electric charge generated by stays only as long as the charged object is near to it.
Answer:
induction

Question 10.
A simple device is used to detect the electric charge on an object.
Answer:
gold leaf electroscope

Question 11.
Lightning is a form of
Answer:
electric charge

Question 12.
The gas protects us from the harmful ultra violet rays coming from the sun.
Answer:
ozone

Question 13.
The is a device used for protection from a lightning strike.
Answer:
lightning conductor

Question 14.
Due to the energy of the lightning, the oxygen in the air is converted into
Answer:
ozone

2. Match the columns:

Question a.

Column ‘A’	Column ‘B’
1. Like charges	a. gold leaf electroscope
2. Unlike charges	b. lightning conductor
3. Copper strip	c. attraction
4. Gold leaves.	d. repulsion

Answer:

Column ‘A’	Column ‘B’
1. Like charges	d. repulsion
2. Unlike charges	c. attraction
3. Copper strip	b. lightning conductor
4. Gold leaves.	a. gold leaf electroscope

Say whether true or false, correct and rewrite the false statement:

Question 1.
Charges cannot be transferred from one body to another.
Answer:
False. Charges can be transferred from one body to another

Question 2.
The word ‘electricity.’ came from the word ‘Elektron’.
Answer:
True

Question 3.
When an inflated balloon is rubbed on silk, it develops a charge.
Answer:
True

Question 4.
An ebonite rod rubbed on woollen cloth develops a positive charge.
Answer:
False. An ebonite rod rubbed on woollen cloth develops a negative charge

Question 5.
A glass rod rubbed on woollen cloth develops a negative charge.
Answer:
False. A glass rod rubbed on woollen cloth develops a positive charge

Question 6.
If the leaves of the electroscope spread only a little, the charge on them is less.
Answer:
True

Question 7.
An atom may have either a positive or a negative charge.
Answer:
False. An atom does not have any charge

Question 8.
When two substances are rubbed on each other, like charges are developed on each.
Answer:
False. When two substances are rubbed on each other unlike charges are developed on each

Question 9.
High rise buildings have lightning conductors.
Answer:
True

Question 10.
It is dangerous to stand under a tree in rainy and stormy weather.
Answer:
True

Give scientific reasons:

Question 1.
Ordinarily, an atom does not have any charge.
Answer:

1. Every atom contains smaller particles with either positive or negative charge.
2. As the number of positively and negatively charged particles in an atom is equal, they neutralize each other.
3. As a result the atom has no charge.

Question 2.
Charge cannot be developed on a copper rod.
Answer:
Charge cannot be developed on a copper rod because only certain pairs of substances give rise to electric charge, on rubbing.

Question 3.
High rise buildings have lightning conductors.
Answer:

1. High rise buildings are prone to lightning strikes during the monsoon.
2. When lightning strikes, a tremendous electric charge is transferred to the earth, which may damage the tall buildings.
3. To prevent this, high rise buildings have a forked metal rod, called a lightning conductor fitted on the top of the building.
4. The lower end of this rod is buried inside the earth.
5. If lightening strikes, the electric charge passes through this conductor and goes in to the earth. In this way the building is saved from damage.

Question 4.
It is dangerous to stand under a tree in rainy and stormy weather.
Answer:

1. Large amount of charges get built up in the clouds in rainy and storming weather.
2. Sometimes these charges are transferred to the earth in the form of a bolt of lightning.
3. Generally lightning strikes tall buildings and trees. If lightning strikes a tree then either the tree may fall or it may catch fire.
4. In both cases this would be dangerous for anyone standing under the tree, hence it is dangerous to stand under a tree in rainy and stormy weather.

Question 5.
Repulsion is a test used for identifying an electrically charged object.
Answer:

1. When a charged object is brought near a neutral object, it gets attracted when two oppositely charged objects are brought close, they get attracted. Therefore, attraction is not a test.
2. But when two like charges are brought close only then repulsion takes place.
3. Therefore, repulsion is the sure test for identifying an electrically charged object.

Question 6.
Mustard seeds when shaken vigorously in a glass bottle stick to the sides of the bottle.
Answer:
When seeds are shaken they get electrically charged and therefore they stick to the neutral walls of the glass.

Answer the following:

Question 1.
Why is the charge developed due to friction called static electric charge?
Answer:
The charge developed due to friction is called 1 static electric charge because the charge remains still on the object.

Question 2.
Why does the charge developed by induction disappear quickly?
Answer:
The charge developed by induction disappears quickly because it is very weak.

Question 3.
Why do the leaves of a gold leaf electroscope fly apart when a charged body touches its disc?
Answer:
The leaves of a gold leaf electroscope fly apart when a charged body touches its disc because like charges develop on both the leaves and hence they repel each other.

Draw a neat labelled diagram of Gold leaf electroscope and describe it.

Answer:

1. This is a simple device to detect the electric charge on object.
2. It consists of a copper rod which has a metal disc at the upper end and two thin gold leaves at the other.
3. The rod is placed in a bottle so that the disc is above the bottle.
4. When an uncharged object is taken near the disc, the leaves remain closed.
5. When a charged object is taken near the disc, both the leaves are charged by the same electric charge, and repel each other.
6. When we touch the disc with our hand, the leaves collapse because the charge in the leaves goes into the earth through our body, and the leaves get discharged.

Use your brainpower:

Question 1.
Do all the objects get charged by rubbing?
Answer:
No. Only certain pairs of substances get charged on rubbing.

Question 2.
Why does a charged balloon stick to a wall?
Answer:
A charged balloon stick to a wall because there is always attraction between a charged object and an uncharged object.

Question 3.
Can we use leaves of some other metal instead of gold, in the electroscope? Which properties must that metal have?
Answer:
We can use other metals than gold in gold leaf electroscope.

1. Only thing is that metal should be malleable and good conductor of electricity.
2. But the best is gold only because we can make extremely thin leaves of gold so even very small charge also can be detected.

Question 4.
What kind of damage is caused by a lightning strike?
Answer:
Due to lightning strike, great damage can occur. It may cause forest fire and burn down things. Person on whom lightning strikes may die. It causes more temperature than sun.

Question 5.
What measures will you take to prevent the damage caused by lightning?
Answer:
Following measures can be taken to prevent the damage caused by lightning:

1. Always put lightning conductor on tall buildings.
2. Do not stand on open ground, below a tree or near the electric or telephone pole during rain/ thunder storms.
3. Do not lean on wired fences.
4. Do not use plugged in electrical appliances.
5. Do not swim during thunder storms.
6. Stay in a pucca house with lightning conductor fitted on it.

Question 6.
Why is the upper end of the lighting conductor pointed?
Answer:

1. The pointed end makes it possible to increase the electric field near the point. The electric field set up at pointed end is high.
2. If the discharge of cloud occurs it would be easily passed through the lightening conductor to the ground and damage to the building is averted.

Question 7.
Why is coal and salt added to the pit in the ground?
Answer:
Coal and salt is filled in the pit and also there is a provision for pouring water into it. This helps to spread electric charge quickly into ground and prevent damage.

Observe the given diagram and answer the questions given.

Question a.
Name the phenomenon happening in the diagram and define it
Answer:
Phenomenon happening is static electricity.
When certain objects are rubbed against each other, they produce an electric charge on their surface at the place of friction. This is due to electrons which remain for a short time. This is called static electricity.

Question b.
What do you observe in “b” and “c” part of the diagram?
Answer:
In ‘b’, we observe attraction between the charged balloon and the uncharged aluminium ball. In ‘c’, we observe that the charge has been transferred to the aluminium ball and due to the same (like) charge, repulsion is observed.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 14 Elements, Compounds and Mixtures Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 14 Elements, Compounds and Mixtures

Class 7 Science Chapter 14 Elements, Compounds and Mixtures Textbook Questions and Answers

1. Who are my companions?

Question a.

Column ‘A’	Column B’
1. Stainless steel	a. Non-metal
2. Silver	b. Compound
3. Bhajani mixture for milling	c. Mixture
4. Salt	d. Element
5. Coal	e. Alloy
6. Hydrogen	f. Metal

Answer:

Column ‘A’	Column B’
1. Stainless steel	e. Alloy
2. Silver	f. Metal
3. Bhajani mixture for milling	c. Mixture
4. Salt	b. Compound
5. Coal	a. Non-metal
6. Hydrogen	d. Element

2. Write the names of elements from the following symbols:
Zn, Cd, Xe, Br, Ti, Cu, Fe, Si, Ir, Pt.

Question a.
Write the names of elements from the following symbols:
Zn, Cd, Xe, Br, Ti, Cu, Fe, Si, Ir, Pt.
Answer:

Symbol	Element
Zn	Zinc
Cd	Cadmium
Xe	Xenon
Br	Bromine
Ti	Titanium
Cu	Copper
Fe	Iron
Si	Silicon
Ir	Iridium
Pt	Platinum

3. What are the molecular formulae of the following compounds?
(Hydrochloric acid, Sulphuric acid, Sodium chloride, Glucose, Methane)

Question a.
What are the molecular formulae of the following compounds?
(Hydrochloric acid, Sulphuric acid, Sodium chloride, Glucose, Methane)
Answer:

• Hydrochloric acid → HCl
• Sulphuric acid → H₂SO₄
• Sodium Chloride → NaCl
• Glucose → C₆H₁₂O₆
• Methane → CH₄
• Water → H₂O
• Carbon dioxide → CO₂
• Sucrose (sugar) → C₁₂H₂₂O₁₁

4. Give scientific reasons:

Question a.
Buttermilk is churned to get butter.
Answer:

1. Churning is the process of shaking up buttermilk to make butter.
2. Butter is essentially the fat of milk.
3. Churning physically agitates the cream until it ruptures the membrane surrounding milk fat
4. Fat droplets can join with each other to form clumps of fat.

Question b.
In Chromatography the ingredients of a mixture rise up to a limited height when water rises up to the upper end of the paper.
Answer:
In Chromatography two properties of substances are used, (a) They are the stability of the substances in the solvent that moves up. The ability of the substance to stick to the stationary filter paper, (b) So all the components of the mixture do not rise all the way to the upper end of the filter paper but remain behind at limited heights.

Question c.
A wet cloth is wrapped around a water storage container in summer.
Answer:
A wet cloth will absorb the heat from the surroundings and it will keep the water in the container, cool for a longer time.

5. Explain the difference.

Question a.
Metals and Non-metals
Answer:

Metals	Non-metals
1. Metals are good conductors of heat and electricity.	1. Non-metals are poor conductors of heat and electricity.
2. Metals are solids at room temperature except for mercury.	2. Non-metals exists in all three states.
3. Metals are lustrous, (shiny)	3. Non-metals are not lustrous, (dull appearance) except graphite.
4. Metals are malleable (can be hammered into sheets)	4. Non-metals are brittle, not malleable.
5. Metals are ductile, can be drawn into wire.	5. Non-metals are not ductile.
6. Metals are very hard and strong.	6. Non-metals are brittle, will break down into pieces except diamond.

Question b.
Mixture and Compound
Answer:

Mixture	Compound
1. The different substances are not chemically joined together to form a mixture but mixed physically.	1. A compound is formed when two or more elements chemically combine together e.g. H2O → chemical formula of water.
2. Each substance in the mixture retains its own properties	2. Compound has fixed properties.
3. Mixtures are impure substances.	3. Compounds are pure substances.
4. Substances from the mixture can easily be separated by physical methods.	4. The constituents of a compound can be separated only by chemical methods.
5. The constituents of a mixture are present in varying proportions.	5. The constituents of a compound are present in fixed proportion.

Question c.
Atoms and Molecules
Answer:

Atoms	Molecules
1. An atom is the fundamental part of matter.	1. A molecule is a group of chemically bonded atoms.
2. Atoms are basic building blocks of matter.	2. Molecule is the smallest unit of a chemical compound
3. It is foundation of molecules.	3. It is foundation of chemical compound.

Question d.
Separation by distillation and Separation by separating funnel
Answer:

Separation by distillation	Separation by separating funnel
1. Distillation is used for purification of impure liquids, for separating liquid and solids (Separation of mixture containing two miscible liquids) e.g. to separate salt and water from saltwater.	1. This procedure is used for separating two liquids e.g. separating oil and water, (two immiscible liquids)

6. Write answers to the following questions in your own words.

Question a.
How are the components of mixture separated by simple methods?
Answer:
1. Component of mixtures are separated by straining, filtering, sifting, picking, sorting, winnowing, combing with a magnet and sublimation.
2. In a mixture, the constituent substances do not lose their identity, they can be separated easily by physical methods.
a. Sedimentation: (i) It is a process of separating an insoluble solid from a liquid in which it is suspended, by allowing it to settle to the bottom of the container, e.g. Muddy water contains heavier particles like sand and soil, (ii) Leave this muddy water undisturbed for some time, (iii) The heavier soil and sand particles settle down and the clear upper water is poured out by decantation.

b. Filtration: It is used for separating insoluble solids from a liquid, e.g. mixture of chalk and water is poured through a filter paper in a funnel while the water gets

collected in the beaker below, chalk is retained in the filter paper.

c. Evaporation: It is used for recovering dissolved solid substances from solutions by evaporation e.g. sugar can be recovered from sugar-water.

d. Distillation: It is a process of heating a solution containing soluble solids to form vapours of the liquid and then cooling the vapours to get the liquid back. e.g. A mixture of common salt and water is taken in distillation flask and heated. Steam rises up and comes out into condenser.

e. Sublimation: It is a process in which some solids on heating are transformed directly to vapour without passing through the liquid state, (i) It is used to separate a mixture of solids. The vapours are cooled separately, (ii) Used to separate ammonium chloride, iodine, camphor and sulphur from any mixture.

f. Magnetic separation: A mixture with iron fillings as one of the components can be separated using magnet to attract the iron particles away from the mixture.

Question b.
Which elements (metals, non-metals) compounds and mixtures do we use in our day to day life?
Answer:
Elements – non-metal

• Oxygen, nitrogen → present in air
• Hydrogen → present in water
• Silicon → in memory card
• Lithium → to make batteries
• Neon → in neon signs/lights
• Sulphur → used in water treatment, agricultural pesticides

Elements – metals

• Calcium → in milk
• Silver, gold → used in jewellery
• Aluminium, copper, iron → Kitchen vessels
• Mercury → in thermometer
• Copper → electric wires

Compounds:

• Sodium chloride → table salt
• Sodium carbonate → washing soda
• Sodium bicarbonate → baking soda
• Sodium hypochloride → bleaching powder
• Sodium hydroxide, Potassium hydroxide → in making soaps
• Calcium oxide, Calcium hydroxide → in white washing the buildings.
• Hydrochloric acid → in cleaning toilets
• Sucrose → sugar used in cooking and baking.

Mixtures:

• Bhel → mixture of puffed rice, sev, groundnuts, lemon juice
• Concrete → mixture of cement, sand and rocks
• Salad → mixture of onion, cucumber, tomato, lettuce, etc.
  Sherbet and saltwater are also mixtures.

Question c.
In everyday life, where and for what purpose do we use centrifugation?
Answer:
Centrifugation: It is a process which involves application of centrifugal force.
1. It is used in industrial and laboratory settings. It is used for separation of fluids, gas or liquid based on density. In centrifugation mixture is separated through spinning and the solid settles to the bottom and the solution is clear.

2. Best example of centrifugal force is working of washing machine when it dries the clothes. The wet clothes are moving in circular path and a force acts on water particles in clothes and this force pulls water all outer side. Force involved is centrifugal force which removes the water from the clothes and clothes are dried in this way.

3. Cream separation: When the machine moves, the rod set inside milk moves and milk is pressurised and solid part from this milk goes outside due to centrifugal force and this solid part is cream. In this way the cream is separated from the milk.

Question d.
Where are methods of separation by distillation and by separating funnel used?
Answer:
1. Distillation: It is the process of separating the components or substances from a compound. It is a process of heating a solution containing soluble solids to form vapours of the liquid and then cooling the vapours to get the liquid back.
Distillation method is used in the following:

• to separate components of air into oxygen, nitrogen, argon, etc.
• to separate salt from saltwater.
• to purify impure liquids.
• to prepare distilled water.

2. Separating funnel: When a mixture of two immiscible liquids is left undisturbed, two layers are clearly seen to have formed, (a) The heavier of the liquids remain below and the lighter liquid floats on it. (b) So two liquids in a mixture can be separated by making use of this property, e.g.

• to separate kerosene and water.
• to separate oil and water.

Question e.
Which precaution will you take while using the methods of distillation and separation by separating funnel?
Answer:
In using distillation:

1. Allow sufficient space to work in, working area should be well lit and well ventilated to prevent the accumulation of alcoholic vapours.
2. Keep a fire extinguisher handy.
3. There should be no obstruction in the piping that could cause pressure build-up in the stills and cause it to burst.

In using separating funnel:

1. Stopper should be tightly fitted so that the solution does not leak out when the separating funnel is inverted.
2. Never throw any layer away until you are absolutely sure that you isolated the final product.

Project:

Question a.
Visit a jaggery or a sugar factory. Obtain information about the methods that are used to separate the components of the mixture while making jaggery or sugar. Present it in the class.

Class 7 Science Chapter 14 Elements, Compounds and Mixtures Important Questions and Answers

Fill in the blanks and rewrite the sentences:

Question 1.
………………, ……………….. and are three states of matter.
Answer:
Solid, liquid, gaseous

Question 2.
Molecules in ……………….. phase of matter are tightly packed together.
Answer:
solid

Question 3.
A ……………….. has a definite volume, but not a definite shape, it takes the shape of its container.
Answer:
liquid

Question 4.
The temperature at which a liquid becomes a solid is called ……………….. .
Answer:
freezing point

Question 5.
Anything that takes up space and has mass is called ……………….. .
Answer:
matter

Question 6.
A ……………….. has no definite shape and no definite volume.
Answer:
Gas

Question 7.
The amount of space that matter occupies is called ……………….. .
Answer:
volume

Question 8.
A ……………….. has a definite shape and definite volume.
Answer:
solid

Question 9.
When a liquid is heated it will ……………….. .
Answer:
expand

Question 10.
A ……………….. is formed by mixing different elements or compounds.
Answer:
mixture

Question 11.
The substance formed by a chemical combination of two or more elements is called a ……………….. .
Answer:
compound

Question 12.
The elements that show some properties of metals and non-metals are called ……………….. .
Answer:
metalloids

Question 13.
Elements are generally classified into ……………….. and ……………….. .
Answer:
metal, non-metals

Question 14.
The smallest particles of substances are called ……………….. .
Answer:
molecules

Question 15.
To date, scientists have discovered ……………….. elements and of these ……………….. elements occur in nature.
Answer:
118, 92

Question 16.
……………….. was the first scientist to use symbols for elements.
Answer:
Berzelius

Question 17.
Symbol for Tungsten is and it is ……………….. and it is derived from its German name ……………….. .
Answer:
W, Wolfram

Question 18.
22-carat gold is an ……………….. of gold.
Answer:
alloy

Question 19.
……………….. of a compound is a short form of its name written using symbols of its constituent elements.
Answer:
Molecular formula

Question 20.
For separating insoluble particles of blood (blood cells) from its liquid part (plasma), ……………….. method is used.
Answer:
centrifugation

Give scientific reason.

Question 1.
Saltwater is a mixture.
Answer:

1. The salt and water are mixed to give saltwater and can both be separated.
2. It can be separated by boiling saltwater.
3. Water can be obtained by condensation whereas the salt will be leftover.
4. As the salt and water do not react chemically and they are separated by simple processes therefore saltwater is called a mixture.

Question 2.
Classify the following substances according to their properties
(water, thermocol, soil, iron, coal, paper, rubber, copper, coir, plastic)
Answer:

Metals	Mixtures	Compounds
Copper, Iron	Soil, Thermocol	Paper, Coir, Plastic, Rubber, Water

Can you tell?

Answer the following questions:

Question 1.
What are objects made of?
Answer:
An object is made of a certain substance, (i) The term matter is also used as a synonym of substance, (ii) Object is made of matter.

Question 2.
What are these articles of everyday use made of?
Answer:

• Electric wire → copper-metal
• Kitchen utensils → stainless steel, Brass-alloy (aluminium-metal).
• Nails → iron-metal
• Tables, chairs → wood, plastic
• Sugar → sucrose
• Window panes → glass
• Salt → NaCl (Sodium chloride) it is a compound.

Question 3.
What do the short-forms Dr, H.M., AC, Adv., C.M., DC stand for?
Answer:
Short forms of Dr. – Doctor, H.M. – Headmaster, AC – Air conditioner, Adv – Advance, C.M. – Chief Minister, DC – Direct current

Question 4.
Which metals do we use in day-to-day life?
Answer:

• Gold and silver → used in jewellery, computer and solar cells
• Iron, copper, aluminium → used to make utensils
• Copper → used in electrical gadgets
• Tungsten → used in electric bulbs.
• Zinc → for coating on iron to prevent rusting
• Tin → for coating on copper and brass vessels
• Iron → nails, agricultural equipments, in construction of buildings, to make steel

Question 5.
Are metals elements?
Answer:
Yes, metals are elements.

Question 6.
Which element helps combustion?
Answer:
Oxygen helps combustion.

Question 7.
Does water help combustion?
Answer:

1. Water is formed by a combination of hydrogen and oxygen but does not help combustion.
2. It is used to extinguish a fire.

Question 8.
What are the mixtures used in everyday life?
Answer:
Oil and water, lemon juice and sherbet, bhel, honey and tea, milk and chocolate, coffee and cream, salt and water, smog (smoke + fog) air (oxygen + nitrogen), salad, milk.

Question 9.
Are all mixtures useful to us?
Answer:
No, adulterated foodstuff is also a kind of mixture and it is not useful. It is harmful, because when an unwanted and harmful substance is mixed with another substance the resulting mixture no longer remains useful.

Question 10.
How will you separate each component from a mixture of semolina, salt and iron filings?
Answer:

1. If a magnet is moved through this mixture all iron filings will stick to the magnet, remove them.
2. Add water to the remaining mixture, all salt will dissolve and then filter through filter paper.
3. Samolina will settle in filter paper.
4. The filtrate will be saltwater and salt can be separated by evaporation or distillation.

Use your brainpower!

Answer the following questions:

Question 1.
In day to day life we come across many things in our surroundings. We touch them, we study their properties. Are all these things made from only one kind of matter or from more than one kind of matters?
Answer:

1. Things are made from only one kind of matter or may be made from more than one kind of matter.
2. When a matter is made up of only one type of atoms it is called an element.
3. We find many elements in our surroundings.
4. But we also see many substances which are made up of two or more elements they are called compounds.
5. Also we see many substances which are formed by physically mixing two or more elements, they are called mixtures.

Question 2.
Classify the following according to the nature of matter in them – whether it is made from one kind of matter or from more than one kind of matter, and whether it is in solid, liquid or gaseous state: an engraved idol, gold, milk, water, a plank, concrete, salt, soil, coal, smoke, sherbet, cooked khichadi, steam.
Answer:

Question 3.
Which of the following are mixtures?
(water, sharbet, iron, steel, coal, air, salt, copper, brass, soil)
Answer:
Mixtures: sherbet, steel, air, brass and soil

Question 4.
Which elements are present in air?
Answer:
Nearly all of the earth’s atmosphere is made up of gases → Nitrogen, Oxygen, Carbon dioxide, Argon and Neon, Helium and Krypton.

Question 5.
Is carbon dioxide an element?
Answer:
No, carbon dioxide is a compound. A molecule of the compound CO₂ contains one atom of the element carbon and two atoms of the element oxygen.

Question 6.
What are the properties of elements due to?
Answer:
Properties of elements are due to molecules present in it. The molecules are made of one or more atoms which are exactly alike. The mass and volume of atoms of different elements are different.

Question 7.
Are the atoms of different elements similar or dissimilar?
Answer:
The atoms of different elements are dissimilar.

Question 8.
Is the water that falls from clouds naturally pure?
Answer:

1. Any form of water that falls from the clouds is known as precipitation. Several forms → rain, snow, hail stones.
2. Yes, it is pure as water vapours condense to form rain.
3. The same process is used in distillation to obtain the purest water.

Question 9.
Which properties of a liquid are seen in the distillation method?
Answer:
Liquid when boiled turns into gaseous state (e.g. water vapours) and on cooling it condenses to liquid.

Question 10.
For what purposes is distilled water used?
Answer:
Distilled water is used in pharmacy as a solvent, in photography to wash the negatives, in laboratory experiments and in cleaning medical tools.

Answer the following questions:

Question 1.a.
Take a piece of chalk and keep on dividing it in to smaller pieces, what will happen?
Answer:
We will get very tiny particles of chalk.

Question b.
Wipe a drop of ink with a handkerchief what effect does it have on the cloth of the handkerchief?
Answer:
The cloth will absorb the ink drop and cloth will have a stain mark on it.

Question c.
What happens when the lid of a bottle of perfume is opened?
Answer:
The molecules of perfume move out of the bottle and collide with other molecules in the air and eventually perfume spreads throughout the room.

Question 2.
Fill water in a spray pump, spray the water and observe the spray.
Answer:
When we spray the water, spray is composed of small particles of water. They are very tiny that we can not see them.

Question 3.
Take water in a tea pot and cover it, heat the water to a boil. What do you see on the inside of the lid?
Answer:

1.  When we boil the water in a tea pot it boils and changes into gaseous state.
2. We find vapours (steam) but when we cover it with a lid, the water vapour cools down, condenses into liquid. So we find water droplets on the inside of the lid.

Question 4.a.
Take sugar in a test tube and heat the test tube. Observe what happens. What remains behind?
Answer:
When a test tube containing sugar is heated, the sugar melts and then it loses water leaving behind a black substance. This black substance is carbon.
Sugar is sucrose, a molecule of sugar is composed of 12 atoms of carbon, 22 atoms of hydrogen and 11 atoms of oxygen. (C₁₂H₂₂O₁₁).

1. Sugar is a compound made from these three elements carbon, hydrogen, oxygen.
2. It is a Carbohydrate.

Question b.
Using tongs hold a magnesium ribbon in a flame and observe what changes took place?
Answer:
When a magnesium ribbon is ignited, light and heat are produced. Magnesium reacts chemically with oxygen in the air
2Mg_(s) + O_2(g) → 2MgO_(s)
Magnesium oxide is produced.

Question c.
What does the name carbon dioxide imply – how many and which elements is this substance made of?
Answer:

1. Carbon dioxide is a compound. It is a tasteless, odourless gas. It is a natural product of respiration.
2. Plants use this to produce food.
3. Humans breath out the CO₂.

[A molecule of the compound carbon dioxide contains one atom of the element carbon and two atoms of the element oxygen.]

Question d.
Which of these are compound, which are elements?
Answer:

• Water → compound H₂O (hydrogen + oxygen), Oxygen → Element
• Carbon dioxide → compound CO₂ (Carbon + Oxygen)

Question e.
What is the smallest particle of a compound called?
Answer:
The smallest particle of a compound is called molecule.

Question 5.
From the internet or reference books obtain information about elements and prepare a table according to the format given below:
Answer:

Question 6.
Some methods of separating the components of a mixture.

Answer:

1. Winnowing
2. Filteration
3. Hand picking
4. Churning
5. Sieving

Question 7.
What is a molecular formula?
Answer:
Like an element, a compound is also written in an abridged form. A molecule of a compound is formed by a chemical combination of atoms of two or more elements. Therefore a molecular formula is used to represent a compound. Molecular formula of a compound is a short form of its name written with the help of the symbols of constituent elements and the number of their respective atoms, e.g.: Nael – Sodium chloride.

Question 8.
Collect information and prepare table:

Write short notes on:

Question a.
Atoms
Answer:
Atoms are basic building blocks of matter. Desk, chair, air are made up of atoms.

Question b.
Compounds
Answer:
1. A compound is a pure substance that contains two or more elements. Compounds are chemical combination of elements with properties that are different from the elements that formed them.
2. Substance is a compound only if its molecules are made up of atoms of different types e.g. Water, one molecule of water is made of two atoms of hydrogen and one atom of oxygen.

Question c.
Mixtures
Answer:

1. A mixture is two or more elements or compounds which are combined physically but no chemical reaction occurs.
2. This means you can separate them again, e.g. air, brass.

Question 9.
Write short notes on:
(1) Distillation (2) Sublimation (3) Magnetic separation (4) Sedimentation (5) Filtration (6) Evaporation
Answer:
1. Distillation: It is a process of heating a solution containing soluble solids to form vapours of the liquid and then cooling the vapours to get the liquid back. e.g. A mixture of common salt and water is taken in distillation flask and heated. Steam rises up and comes out into condenser.

2. Sublimation: It is a process in which some solids on heating are transformed directly to vapour without passing through the liquid state, (i) It is used to separate a mixture of solids. The vapours are cooled separately, (ii) Used to separate ammonium chloride, iodine, camphor and sulphur from any mixture.

3. Magnetic separation: A mixture with iron fillings as one of the components can be separated using magnet to attract the iron particles away from the mixture.

4. Sedimentation: (i) It is a process of separating an insoluble solid from a liquid in which it is suspended, by allowing it to settle to the bottom of the container, e.g. Muddy water contains heavier particles like sand and soil, (ii) Leave this muddy water undisturbed for some time, (iii) The heavier soil and sand particles settle down and the clear upper water is poured out by decantation.

5. Filtration: It is used for separating insoluble solids from a liquid, e.g. mixture of chalk and water is poured through a filter paper in a funnel while the water gets collected in the beaker below, chalk is retained in the filter paper.

6. Evaporation: It is used for recovering dissolved solid substances from solutions by evaporation e.g. sugar can be recovered from sugar-water.

Question 10.
Name the method you will use to separate the following mixtures:

1. Cream from buttermilk.
2. Mud from muddy water.
3. Stones from grains.
4. Tea leaves from boiled tea.
5. Salt from water.
6. Kerosene and water.
7. Blood cells and plasma.
8. Ink from water

Answer:

1. Churning
2. Sedimentation and decantation
3. hand picking
4. filtration
5. distillation
6. separating funnel
7. Centrifugation
8. Chromatography

Question 11.
Draw the experimental setup of weperation using separating funnel:
Answer:

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 19 Properties of a Magnetic Field Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 19 Properties of a Magnetic Field

Class 7 Science Chapter 19 Properties of a Magnetic Field Textbook Questions and Answers

1. Write the appropriate terms in the blanks:

Question a.
The alloys called …………. and …………. are used for making industrial magnets.
Answer:
alnico, Nipermag

Question b.
A magnetic field can pass through ………… and …………. .
Answer:
cardboard, bottle

Question c.
The intensity of a magnetic field is indicated by the lines of …………. .
Answer:
force

Question d.
The real test of a magnet is ……………… .
Answer:
repulsion

2. With whom should I pair up?

Question a.

Column ‘A’	Column ‘B’
1. Compass	a. The highest magnetic force
2. Door of a cupboard	b. Like poles
3. Repulsion	c. A magnet
4. Magnetic pole	d. A magnetic needle

Answer:

Column ‘A’	Column ‘B’
1. Compass	d. A magnetic needle
2. Door of a cupboard	c. A magnet
3. Repulsion	b. Like poles
4. Magnetic pole	a. The highest magnetic force

3. Write answers to the following questions:

Question a.
Distinguish between the two methods of making artificial magnets
Answer:

Single touch method	Double touch method
1. In this method, one magnet is used to magnetise the steel bar.	1. In this method, two magnets are used to magnetise the steel bar.
2. In this method, the magnet is dragged from one end of the steel bar to another end.	2. In this method, two magnets are dragged from the middle of the steel bar to the opposite directions.
3. As only one magnet is used to induce magnetism, this method is called single touch method.	3. As two bar magnets are used to induce magnetism, this method is called double-touch method.
4. The magnetism created by this method is of low strength and lasts for a short time.	4. The magnetism created by this method is of high strength and lasts for a longer time.

Question b.
Which substances are used for making electromagnets?
Answer:
The substances used for making electromagnets are, an iron nail, insulated copper wire, one or more batteries and a pair of wire strippers.

Question c.
Write a note on magnetic field
Answer:

1. The region around a magnet where the magnetic force acts on an object is called a magnetic field.
2. The magnetic field around a magnet can be shown by means of magnetic lines of force.
3. The intensity of the magnetic field can be obtained from the number of lines of force.
4. The intensity of a magnetic field is low where the lines of force are sparse and the intensity is high where the lines of force are concentrated.
5. A magnetic field is the magnetic effect of electric currents and magnetic materials.
6. The magnetic field at any given point is specified by both the direction and the magnitude.
7. Magnetic fields are produced by electric current.

Question d.
Why is a magnetic needle used in a compass?
Answer:

1. The magnetic compass is the most familiar compass type.
2. It functions as a pointer to magnetic ‘north’ the local magnetic meridian, because the magnetized needle at its heart aligns itself with the horizontal component of the earth’s magnetic field.
3. A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal direction.

Question e.
Explain with the help of a diagram how the intensity and direction of the magnetic field of a bar magnet can be determined.
Answer:

1. The region around a magnet where the magnetic force acts on an object is called a magnetic field.
2. The magnetic field around a magnet can be shown by means of magnetic lines of force.
3. The intensity of the magnetic field can be obtained from the number of lines of force.
4. The intensity of a magnetic field is low where the lines of force are sparse and the intensity is high where the lines of force are concentrated.
5. A magnetic field is the magnetic effect of electric currents and magnetic materials.
6. The magnetic field at any given point is specified by both the direction and the magnitude.
7. Magnetic fields are produced by electric current.

4. Give detailed information about how the merchants of olden times used a magnet while travelling.

Question a.
Give detailed information about how the merchants of olden times used a magnet while travelling.
Answer:

1. The merchants of older times used a magnet whose north-south side was known.
2. When the magnet is freely suspended, the north pole of the magnet settles in the direction of the geographic north pole of the earth.
3. This is how the merchants come to know the directions while travelling.
4. The idea for using loadstone in a compass first appeared in China.
5. The first compass were made of loadstone, a naturally magnetised ore of iron.
6. The Chinese used “south pointing spoon” which when thrown upon the ground comes to rest pointing at the south.
7. Then the transition was made from loadstone spoons to iron needles.
8. In the medieval period a magnetic needle in the shape of a fish, floating in the bowl of water was used as a compass, pointing south.
9. It was called floating compass.
10. In the twentieth century, liquid filled magnetic compass began to appear.
11. There is a lesser known compass called dry mariners compass.

Project:

Question a.
Obtain information about the function of metal detectors.

Class 7 Science Chapter 19 Properties of a Magnetic Field Important Questions and Answers

Write the appropriate terms in the blanks:

Question 1.
The magnetic lines of force always run from the north pole to the ……………. .
Answer:
south pole

Question 2.
The unit of magnetic field strength is …………….. .
Answer:
A/M (Amperes per metre)

Question 3.
The earth behaves like a giant ………… .
Answer:
barmagnet

Question 4.
The ……………. properties of magnetic field was proposed by scientist
Answer:
Michael Faraday

Question 5.
The region around a magnet where the magnetic force acts on an object is called the …………. .
Answer:
magnetic field

Question 6.
The ……………. of the magnetic field can be obtained from the number of lines of force.
Answer:
strength

Question 7.
The function of the metal detector is based on ………… .
Answer:
electromagnets

Question 8.
The magnetism is ………….. in the case of an electromagnet.
Answer:
temporary

Match the following:

Question 1.

Column ‘A’	Column ‘B’
1. Iron, nickel, cobalt	a. Electromagnet
2. Doorbell magnet	b. Permanent magnet
3. Nickel, cobalt, aluminium	c. Iron, nickel, titanium, aluminium
4. Cupboard magnet	d. Magnetic metals
5. Lodestone	e. Mariner’s compass
6. Nipermag	f. Alnico

Answer:

Column ‘A’	Column ‘B’
1. Iron, nickel, cobalt	d. Magnetic metals
2. Doorbell magnet	a. Electromagnet
3. Nickel, cobalt, aluminium	f. Alnico
4. Cupboard magnet	b. Permanent magnet
5. Lodestone	e. Mariner’s compass
6. Nipermag	c. Iron, nickel, titanium, aluminium

Write True or False correct and rewrite the false statements:

Question 1.
Material alnico is a mixture of aluminium, nickel and iron.
Answer:
False. Alnico is an alloy of aluminium, nickel and cobalt

Question 2.
Nipermag is alloy of iron, nickel, cobalt.
Answer:
False. Nipermag is an alloy of iron, nickel, aluminium and titanium

Question 3.
The magnetic force is concentrated at the centre of the magnet.
Answer:
False. The magnetic force is concentrated at the poles of the magnet.

Question 4.
Magnetism of electromagnet is permanent.
Answer:
False. Magnetism of electromagnet is temporary

Question 5.
Like poles attract each other and unlike poles repel each other.
Answer:
False. Like poles repel each other and unlike poles attract each other

Question 6.
Two poles of a magnet cannot be separated from each other.
Answer:
True.

Answer in one or two sentences:

Question 1.
In which direction does a freely suspended magnet settle?
Answer:
The north pole of a freely suspended magnet settles in the direction of the geographic north pole of the earth. It settles in north-south direction.

Question 2.
Write any two functions of metal detectors.
Answer:

1. Metal detectors are used in very important places like an airport, bus station, certain temples and buildings to inspect those who are entering these places.
2. To detect very precious articles.

Question 3.
Which magnetic poles attract each other?
Answer:
Opposite magnetic poles attract each other.

Question 4.
What metals are used for making magnets?
Answer:

1. Magnets are made from alloys of iron, cobalt and nickel.
2. Nipermag is an alloy made up of iron, nickel, aluminium and titanium whereas alnico is an alloy made up of aluminium, nickel and cobalt.

Give scientific reasons:

Question 1.
Earth is called as a gigantic magnet.
Answer:

1. The earth is called as a gigantic magnet because north pole of a freely suspended magnet always settles in the direction of the geographic north pole of the earth.
2. It means that the South pole of some gigantic magnet must be near the geographic north pole of that magnet, near the geographic south pole of the earth.
3. Gilbert inferred from this that the earth itself is a gigantic magnet.

Question 2.
A bar magnet kept on the cardboard arranges the iron fillings in line.
Answer:

1. A bar magnet kept on the cardboard arranges the iron fillings in line because of the ‘magnetic lines of force’.
2. These magnetic lines gauge the intensity of the bar magnet.
3. The intensity of the magnetic field is low where the lines of force are sparse and the intensity is high where the lines of force are concentrated.
4. Therefore, the iron fillings arrange themselves according to intensity of the magnetic lines of force.

Write short note on:

Question 1.
Functions of metal detector.
Answer:

1. A metal detector is an electronic instrument which detects the presence of metals nearby.
2. The function of these machines is based on electromagnets.
3. Metal detectors are useful for finding metal inclusions hidden within objects, or metal objects buried underground.
4. They often consist of a handheld unit with a sensor probe which can be swept over the ground or other objects.
5. Metal detectors in the food manufacturing industry are used to detect and eliminate threats of metal contaminants in food.
6. Metal detectors are used in very important places like an airport, bus station, temples, hospitals, railway stations, theaters, malls.
7. They are used for inspection of persons entering these places.
8. In geology, these machines are used to detect the presence and quantity of metals.

Question 2.
Write down the characteristics of magnets.
Answer:

1. A freely suspended magnet settles in the north- south direction always.
2. Magnets attract objects of iron, cobalt and nickel.
3. The force of attraction of a magnet is greater at its poles than in the middle.
4. Like poles of two magnets repel each other.
5. Opposite poles of two magnets attract each other.
6. If a bar magnet is suspended by a thread and if it is free to rotate its south pole will move towards the north pole of the earth.

Question 3.
Characteristic of magnetic lines of force
Answer:

1. Magnetic lines of force start from the north pole and end at the south pole.
2. They are continuous through the body of magnet. These are imaginary lines.
3. Magnetic lines of force can pass through iron more easily than air
4. The number of magnetic lines force determines the strength of the magnetic field at a particular point.
5. Two magnetic lines of force do not intersect each other.
6. They contract longitudinally and expand laterally.

Can you tell?

Answer the following questions:

Question 1.
Why does freely suspended magnet always settle in the north-south direction?
Answer:

1. Gilbert gave a scientific explanation that earth itself is a gigantic magnet.
2. The north pole of a freely suspended magnet settles in the direction of the geographic north pole of the earth since unlike poles attract.
3. It means that the south pole of some gigantic magnet must be near the geographic north pole of the earth.
4. In other words, the thing we call Earth’s geographic north pole is actually the south pole of the magnet inside the earth.
5. That is why a freely suspended magnet always settles in geographic north-south attracted by opposite poles of the earth as a great magnet.

Question 2.
Which magnetic poles attract each other?
Answer:
Opposite magnet poles attract each other.

Question 3.
Which pole of a spherical magnet will get attracted towards the south pole of the bar magnet?
Answer:
The north pole of the spherical magnet will get attracted towards the south pole of the bar magnet.

Question 4.
Why does a bar magnet kept at a distance doesn’t attract pins?
Answer:

1. The region around the magnet where the magnetic force acts is known as the magnetic field.
2. It has its influence over a certain distance where these magnetic lines of force act.
3. As these pins are outside this area of influence, a bar magnet does not attract those pins which are at a distance.

Question 5.
What is an electromagnet?
Answer:

1. A soft metal core made into a magnet by the passage of electric current through a coil surrounding it is called an electromagnet.
2. An electromagnet is a magnet in which the magnetic field is produced by electricity.
3. The strength of an electromagnet can easily be changed by changing the amount of electric current that flows through it.
4. The poles of an electromagnet can even be reversed by reversing the flow of electricity.
5. An electromagnet works because an electric current produces a magnetic field.
6. The magnetic field produced by electric current forms circles around the electric current.
7. The magnetic field disappears when the current is turned off.

Question 6.
How can an electromagnet be made?
Answer:

1. It is easy to make an electromagnet. To make an electromagnet we needs an iron nail of 10 cm length 1 metre long insulated copper wire, a battery cell, pins.
2. Neatly wrap some insulated copper wire around an iron nail.
3. The more wires you wrap around the nail, the stronger will be the electromagnet.
4. Attach a battery to the wire, an electric current will begin to flow and the iron nail will become magnetised.
5. When the battery is disconnected the iron nail will lose its magnetism.

Use your brainpower!

Answer the following questions:

Question 1.
Which direction will a magnetic needle show on the geographic north pole?
Answer:
North, all magnetic needle will show north direction.

Question 2.
Is magnetic force a vector or a scalar quantity?
Answer:

1. It is a vector quantity. Because a magnetic field is the magnetic effect of electric current and magnetic materials.
2. The magnetic field at any given point is specified by both direction and magnitude as such it is represented by a vector field.

Question 3.
What is meant by magnetic force?
Answer:

1. The magnetic force, is a consequence of the electromagnet force, one of the four fundamental forces of nature.
2. It occurs whenever objects interact in which there is charge in motion, eg. compass, a motor.
3. Magnetic force is an attraction or repulsion that arises between electrically charged particles because of their motion.

Question 4.
How does a magnetic force act without direct contact?
Answer:
Magnetic force acts without even direct contact because of the penetrating ability of the magnetic field.

Question 5.
What is the difference between the gravitational force and magnetic force?
Answer:

Gravitational Force	Magnetic Force
1. Gravitational force acts between any objects with mass.	1. Magnetic force acts between objects with specific properties.
2. It depends on the mass of the objects.	2. It does not depend on the mass of objects.
3. It acts over long-range as a gravitational field is large.	3. It acts over short-range as magnetic field is short.
4. Object are always attracted to each other.	4. Objects are either attracted or repelled.

Question 6.
Why is repulsion the real test for identifying a magnet?
Answer:
A magnet can attract the opposite pole of the magnet as well as magnetic substances (iron, cobalt, nickel).
So if a magnet attracts another object, we cannot say that other object is a magnet or a magnetic substance.
But if the magnet repels the object then we can surely say that the other object is a magnet because like poles of magnets repel each other.

Question 7.
How will you find a magnet from among the various articles given to you?
Answer:

1. Magnet has the property to attract things made of iron, cobalt, nickel.
2. A magnet has magnetic field which is invisible but it has the property of attracting, pulling other
3. ferromagnetic material such as iron, cobalt and nickle.
4. So if we bring any iron, nickle objects near it, they will be pulled toward the magnet.
5. The real test is repulsion.
6. The article which shows repulsion when one of the poles of a magnet is brought near is surely a magnet.

Find out:

Answer the following questions:

Question 1.
Why does the magnetic needle of a compass not settle parallel to the ground but at an angle to it?
Answer:

1. Freely suspended magnet does not point to north, but aligns to earth’s magnetic field axially ie – north-south.
2. The magnetic pole of the earth is different from true north (geographic north) because the magnetic north is constantly changing.
3. It leads to a margin of error called declination in which there is an angle of difference (11.51)° between Magnetic North and True North.
4. That is the reason the magnetic needle does not settle parallel to the ground.

Observe the diagrams and answer the questions given below:

Question 1.
Name the methods shown.
Answer:
Single touch and Double touch methods of magnetising a steel bar.

Question 2.
Give 2 points of difference between the methods.
Answer:

Single touch method	Double touch method
1. In this method, one magnet is used to magnetise the steel bar.	1. In this method, two magnets are used to magnetise the steel bar.
2. In this method, the magnet is dragged from one end of the steel bar to another end.	2. In this method, two magnets are dragged from the middle of the steel bar to the opposite directions.
3. As only one magnet is used to induce magnetism, this method is called single touch method.	3. As two bar magnets are used to induce magnetism, this method is called double-touch method.
4. The magnetism created by this method is of low strength and lasts for a short time.	4. The magnetism created by this method is of high strength and lasts for a longer time.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 18 Sound: Production of Sound Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 18 Sound: Production of Sound

Class 7 Science Chapter 18 Sound: Production of Sound Textbook Questions and Answers

1. Fill in the blanks:

Question a.
Sound is generated by the rhythmic ……………. of any object.
Answer:
vibrations

Question b.
The frequency of sound is measured in …………….. .
Answer:
Hertz (Hz)

Question c.
If …………….. of sound is decreased its loudness also decreases.
Answer:
intensity

Question d.
A medium is necessary for …………… of sound.
Answer:
generation

2. Match the pairs.

Question a.

Column ‘A’	Column ‘B’
1. Flute	a. Frequency less than 20 Hz
2. Frequency	b. Frequency more than 20,000 Hz
3. Sound level	c. Vibrations in the air
4. Ultrasonic sound	d. Measured in Hz
5. Infrasonic sound	e. Decibel

Answer:

Column ‘A’	Column ‘B’
1. Flute	c. Vibrations in the air
2. Frequency	d. Measured in Hz
3. Sound level	e. Decibel
4. Ultrasonic sound	b. Frequency more than 20,000 Hz
5. Infrasonic sound	a. Frequency less than 20 Hz

3. Give scientific reasons.

Question a.
In earlier times, people used to listen for the arrival of a distant train by putting their ear to the rails.
Answer:

1. It was a technique that worked better in those days when train speed were slower than they are today and when there were more rail joints.
2. When people would put their ear to the rail they could hear vibration caused by the wheels moving over the joints. ,
3. Metal being a solid is an efficient medium for the sound to travel and so the sound can propagate further in the rail than would in air as speed of sound is faster in solids than in air.

Question b.
The sounds generated by a tabla and sitar are different.
Answer:

1. In tabla where leather is fitted, sound gets generated when the leather surface is thumped by fingers or palm.
2. The waves thus created travel in two dimensions. Sitar is having strings attached to pumkin box called sound box.
3. Sounds generated by tabla and a sitar are different because they have different pitch and frequencies.

Question c.
If you were both on the moon your friend will not be able to hear you call.
Answer: Yes, your friend will not be able to hear your call because sound needs a medium for transmission since it is a mechanical wave it cannot travel through vaccum.

1. As there is no air on the moon and sound is actually vibration in air.
2. So astronauts communicate to each other by signals or microphones in space even when they are closer.

Question d.
We can hear the movement of a mosquito wings but we cannot hear the movement of our hands.
Answer:

1. Humans cannot hear frequency less than 20 Hz. In the movement of hands oscillations does take place but is less than frequency that humans can hear.
2. Mosquitos wings flap in air.
3. When they fly in air it produces buzzing sound in our ears.
4. The movement of mosquito wings produces sound greater than 20 Hz.
5. Sound is the reception of such waves and their perception by the brain.

4. Write answers to the following questions.

Question a.
How is sound produced?
Answer:

1. Sound is generated due to the vibration of an object, e.g. bell, string or diaphragm of a musical instrument.
2. Vibrations are imparted to the molecules in the air. These vibrations reach our ears through the air and sound is heard.
3. Vibrations of an object is necessary for generation of sound.
4. These vibrations in air are called travelling longitudinal waves which we can hear.

Question b.
What does the intensity of sound depend upon?
Answer:

1. The intensity of sound is proportional to the square of the amplitude of vibration, e.g. If the amplitude is doubled the intensity of sound becomes four times.
2. Therefore the loudness or softness of sound is dependent on the intensity of sound and sound level.

Question c.
Explain how the frequency of oscillation is related to the length of a pendulum and the amplitude of its oscillation.
Answer:

1. Given an oscillatory motion to the pendulum, the maximum distance between the original position A of the pendulum and extreme position B or C is called the amplitude of oscillation. AB, AC is the amplitude of oscillation.
2. The number of oscillations completed by an oscillator in one second is called the frequency of oscillation.

Relation between frequency and length of a pendulum: If the length of the pendulum increases the period of oscillations also increases.
We know time period of oscillations = \(\frac{1}{\text { Frequency }}\)
If time period increases, frequency decreases, therefore, if the length of the pendulum increases frequency will decrease.
Relation between frequency and amplitude: Frequency of oscillation is independent of its amplitude of oscillation.

Question d.
Explain the two ways by which the pitch of the sound generated by a stretched string can be changed?
Answer:
1. A string vibrates with a particular fundamental frequency. It is however possible to produce pitches with different frequencies from the same string.

2. The two properties of the string that affect its frequency are length and diameter.

3. When the length of a string is changed, it will vibrate with a different frequency. Shorter strings have higher frequency and therefore higher pitch.

4. When a musician presses her finger on a string, she shortens its length. The more fingers she adds to the string, the shorter she makes it, higher will be the pitch.
Diameter: Thick strings with large diameter vibrate slower and have lower frequency than the thin ones.

Project:

Question a.
The bat, a mammal, flies during the night manoeuvering with the help of the ultrasonic sounds it produces. Find out more about this.

Class 7 Science Chapter 18 Sound: Production of Sound Important Questions and Answers

Fill in the blanks:

Question 1.
Bats detect the obstacles in their path by receiving the reflected ………….. .
Answer:
ultrasonic waves

Question 2.
An object that moves back and forth is called ……………. .
Answer:
an oscillator

Question 3.
If the length of a pendulum is increased the time period of oscillation ………………. .
Answer:
increases

Question 4.
The …………… of a wave is the maximum distance moved by the object on either side of the mean position.
Answer:
amplitude

Question 5.
Sound waves do not travel through ……………… .
Answer:
vaccum

Question 6.
The frequency above which sound is not audible to the human ear is …………….. .
Answer:
50,000 Hz

Question 7.
Number of vibrations in a second is called …………….. .
Answer:
frequency

Question 8.
Higher the frequency greater will be the ………….. .
Answer:
Pitch

Question 9.
The loudness of sound depends on ………….. .
Answer:
amplitude

Question 10.
Loudness of sound is measured in units of ………………. .
Answer:
decibel dB

Question 11.
100 hertz is equal to hundred oscillations in ………………. .
Answer:
one second

Name the following:

Question 1.
The sound frequencies above 20,000 Hz.
Answer:
ultrasonic

Question 2.
The medium through which sound is most clearly propagated.
Answer:
solids

Question 3.
The range of frequency in which humans can hear sound.
Answer:
20 – 20,000 Hz

Question 4.
The sound level physically painful to humans.
Answer:
above 100 dB

Question 5.
The technique used by bats to find their way.
Answer:
echolocation

Question 6.
The unit of frequency of sound.
Answer:
Hertz

Question 7.
The unit of sound level or intensity.
Answer:
Decibel

Question 8.
The scientist in whose honour was the unit decibel named for intensity of sound.
Answer:
Alexander graham Bell

Question 9.
Bats and dolphins can hear these sound frequencies.
Answer:
Ultra sonic sound

Question 10.
The sound frequencies used in RADAR systems.
Answer:
Ultra sonic sound

Answer in one or two sentences:

Question 1.
How is sound produced?
Answer:
Sound is produced by vibration of an object.

Question 2.
What produces sound in human beings ?
Answer:
The vibration of the vocal chords in our larynx or voice box produces sound.

Question 3.
What is oscillatory motion?
Answer:
To and fro motion of an object (oscillator) on either side of a central position is called oscillatory motion.

Question 4.
What is periodic motion?
Answer:
The motion of an object repeated again and again at fixed intervals of time is called periodic motion.

Question 5.
What is frequency of oscillation?
Answer:
The number of oscillations completed by an oscillator in one second is called the frequency of oscillation.

Question 6.
How is intensity of sound and amplitude of vibration related?
Answer:
The intensity of sound is proportional to the square of the amplitude of vibration. For example, if the amplitude is doubled the intensity becomes four times as much.

Question 7.
What happens if the frequency of sound is greater than 1000 Hz or 100 dB?
Answer:
If frequency of sound is increased more than 100dB, the hearing can be temporarily affected which can result in temporary deafness.

Question 8.
What is infrasonic sound?
Answer:
A sound with a frequency less than 20Hz is called infrasonic sound.

Question 9.
What is application of ultrasonic sound?
Answer:
Ultrasonic sound is used in ships as a system known as ‘SONAR’ to detect the obstacle beneath the ocean as well as the depth of an ocean.

Question 10.
What is the difference between pitch and frequency?
Answer:
Pitch is directly proportional to the frequency of a sound whereas frequency is the repeating vibrations per unit time.

Question 11.
What happens when the rubber band is stretched with a greater force and released?
Answer:
When a rubber is stretched with a greater force and released, the amplitude increases which in turn result in a louder sound being generated.

Question 12.
What happens to frequency if the amplitude is changed?
Answer:
The frequency remains the same even if the amplitude is increased or decreased.

Define:

1. Echo: It is a repetition of sound due to the reflection of original sound by a large and hard obstacle.
2. Frequency: It is defined as the number of vibrations per unit time.
3. Hertz (Hz): One hertz is one vibration per second.
4. Ultrasonic vibration: Sounds of frequency higher than 20,000 Hz are called the ultrasonic.
5. Time period: The time taken by an object to complete one oscillation is called time period.
6. Amplitude: The distance between the mean or central position to the extreme position of an oscillator on either side is called amplitude.

Say True or False with explanation:

Question 1.
Sound cannot travel in vacuum.
Answer:
True. Sound needs a medium to travel through. Since vacuum does not provide any medium, sound cannot travel through it.

Question 2.
If the amplitude of vibration is large, sound is feeble.
Answer:
False. When the amplitude of vibration of a sound is large, the sound is very loud. The sound is feeble, when the amplitude is small. Loudness of a sound is proportional to the square of the amplitude of its vibration.

Question 3.
For human ears, the audible range is 2 Hz to 20,000 Hz.
Answer:
True. Human being can hear sounds only within the range of 20-20,000 Hz. We cannot hear the sound having frequency out of this range.

Question 4.
The lower the frequency of vibrations the higher is the pitch.
Answer:
False. Pitch of sound increases when the frequency of vibration increases. The pitch of a sound is directly proportional to its frequency.

Question 5.
Unwanted or unpleasant sound is termed as music.
Answer:
False. Unwanted, or unpleasant sounds are termed noise. Sounds which are melodious, and pleasing to ears are called music.

Question 6.
Noise pollution may cause partial hearing impairment.
Answer:
True. Unwanted, unpleasant sounds are called noise. If one is subjected to noise continuously for a long time, one may suffer from partial hearing impairment.

Question 7.
Time taken by an object to complete one oscillation is called time period.
Answer:
True. Time taken by an object to complete one oscillation is called time period.

Solve the following problems:

Question 1.
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Answer:
Frequency is the number of oscillations per second of a vibrating body.

The time taken to complete one oscillation (to and fro) is known, as time period.

Question 2.
The sound from a mosquito, is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
Answer:
The time taken to complete one oscillation (to and fro) is know as time period.

Give scientific reasons:

Question 1.
Loud speakers should not be put in congested areas.
Answer:

1. The loudness or softness is indicated by the intensity of sound and sound level.
2. By putting loud speakers in congested areas, the intensity of sound being more than 100 dB will cause ill effects like temporary deafness and a prolonged exposure can lead to permanent damage.

Answer the following:

Question 1.
Why are the ceilings of concert halls curved?
Answer:
The ceilings of concert halls are curved because sound after reflection from the ceiling it reaches all the comers of the hall and is audible to each person in the hall.

Question 2.
Have you ever heard the sound of movement of hands and falling of leaves from a tree?
Answer:

1. The term infrasonic refer to sound waves below the frequencies of audible sound i.e. under 20 Hz.
2. Humans cannot hear infrasonic sound.
3. Movement of hands and falling of leaves comes below this audible range. Therefore we cannot hear these sounds.

Question 3.
How can dogs perceive in advance the signals of an impending earthquake?
Answer:
Dogs can hear sounds upto about 65,000 Hz. That’s why dogs can receive ultrasonic sound signals produced by the vibration of the earth and start barking in advance before the actual earthquake is felt.

Question 4.
State the uses of Ultrasonic sound.
Answer:
Uses of Ultrasonic sound are:

1. To clean delicate ornaments and the tiny parts of a watch.
2. To observe internal organs of the body.
3. To detect tumors in the brain.
4. To detect faults in a metal.
5. In RADAR systems
6. To Kill certain microbes and insects.
7. SONAR (Sound navigation and ranging) is used to locate the seabed or the position of a ship.

Use your brainpower!

Answer the following questions:

Question 1.
Will a sound be generated no matter how the ruler is kept on the table.

Answer:

1. No, If the ruler kept on the table is only a little part off the table, it will not vibrate with a greater force.
2. On the contrary if the ruler is kept with a larger portion off the table it will vibrate with a greater force generating louder sound.

Question 2.
Is there any correlation between the length of the free part of the ruler and the sound generated?
Answer:
Yes, vibrating ruler pushes the molecules in the air producing sound waves. More the length of free part of ruler less will be the vibrations and less will be the frequency and pitch of the sound. If the length of free part of ruler is shorter it vibrates more quickly producing sound of higher frequency and pitch.

Question 3.
If the ruler is plucked while it is held with 25 cm of it off the table, does it makes any sound? If there is no sound, look for the reason why it is so?
Answer:
No, the ruler vibrates very slowly, which has frequency which is not audible.

Question 4.
What would be the difference perceived between hearing only two pupils in the class talking to each other and all the children talking to one another at the same time?
Answer:

1. When two pupils talk to each other, the sounds of two frequencies produced can be heard clearly.
2. When all the children talk to one another sounds of many frequencies produced can not be heard clearly.
3. Sound level will be more creating loud noise.

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 13 Changes – Physical and Chemical Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 13 Changes – Physical and Chemical

Class 7 Science Chapter 13 Changes – Physical and Chemical Textbook Questions and Answers

1. Distinguish between the following.

Question a.
Physical change and Chemical change
Answer:

Physical changes	Chemical changes
1. In a physical change material may change its	1. A change which after physical properties and
shape, size, texture or state.	composition also.
2. No new compound is formed.	2. New compound /substance is formed due to chemical change.
3. The change is temporary. It is reversible.	3. The change is permanent and irreversible.
4. Examples: Evaporation of water, boiling of water, melting of ice.	4. Examples: Burning of wood, paper, souring of milk, digestion of food, rusting of iron.

Question b.
Periodic changes and Non-periodic change
Answer:

Periodic changes	Non-periodic change
1. Some changes occur again and again after a definite interval of time. Such changes are called periodic changes.	1. In this, certain changes will recur after one occurrence, it cannot be said for sure, even if they occur interval is not fixed. Such changes are called non-periodic changes.
2.  Examples: movement of clock hands in clock showing time, change of season, day and night formation, heart beat, ripening of fruit, rising and setting of the sun.	2. Examples: volcanic eruption, occurrence of an earthquake, tsunami, forest fires, freezing of water to form ice, sneezing, rusting of iron.
3. They repeat themselves after a fixed interval of time.	3. They do not repeat themselves after a fixed interval of time.

Question c.
Natural change and Man-made change
Answer:

Natural change	Man-made change
1. Changes that occur naturally on its own are called natural changes.	1. Changes that are result of human activity. Such changes are called man-made.
2. Examples ripening of a fruit, spoiling of milk, change in the climate	2. Burning of fossil fuels, deforestation, pollution of air, water and soil.

2. Under which different types can the following changes be classified?

Question a.
Conversion of milk into yoghurt.
Answer:
Manmade (useful).

Question b.
Bursting of cracker.
Answer:
Manmade (fast change).

Question c.
Occurrence of an earthquake.
Answer:
Non-periodic.

Question d.
Revolution of earth around the sun.
Answer:
Periodic. (Natural change)

Question e.
Stretching of a spring.
Answer:
Physical, reversible change.

3. Give reasons.

Question a.
While purchasing canned food, its expiry date should be checked.
Answer:

1. Canned food is processed food.
2. After certain period of time it may get spoilt due to some growth of micro-organism it may get intoxicated.
3. If we consume such food we may get food poisoning, so we should check the expiry date.

Question b.
An iron article should be given a coat of paint.
Answer:

1. When an iron article is kept for long time it gets corroded due to presence of oxygen in atmosphere.
2. Iron gets oxidized to iron oxide which forms a reddish brown layer on it and iron gets rusted.
3. It is called corrosion. Due to corrosion things become weak.
4. So an iron article should be given a coat of paint so that it is protected against corrosion.
5. Paint gives protection to iron.

Question c.
A Wooden article should be polished.
Answer:

1. When a wooden article comes in contact with moisture there is possibility of fungal growth and also termites will make wooden article brittle and break.
2. So a wooden article should be polished which forms a protective layer.
3. It does not allow the wooden article to get decayed by moisture or attacked by termite.

Question d.
Copper and brass utensils should be tinned.
Answer:

1. Due to corrosion of copper or brass a greenish layer is seen to form on it.
2. So to protect copper and brass utensils from corrosion they are coated with tin.
3. This process is called thinning.

Question e.
A dry handkerchief gets wet at once on dipping in water, but it takes long for a wet handkerchief to dry.
Answer:

1. The dry fibres of handkerchief absorbs water to its maximum capacity immediately that is why handkerchief gets wet at once.
2. When wet handkerchief dries, all the water absorbed has to become water vapour by evaporation.
3. This depends on surrounding air and heat.
4. That is why wet handkerchief takes a long time to dry.

4. What will you take into account while identifying the following:

Question a.
A physical change in a substance.
Answer:
I will take into account the following facts.

1. Whether the shape, size or state of the substance is changed.
2. Whether it is a temporary change.
3. Whether it is a reversible change.

Question b.
A chemical change in a substance.
Answer:
I will take into account the following facts.

1. Whether a new substance is formed.
2. Whether it is a permanent change.
3. Whether it is a non-reversible change.

5. Read the paragraph and note down the various types of changes it mentions.

Question a.
Read the paragraph and note down the various types of changes it mentions.
It was nearing six o’clock in the evening. The sun was setting. A breeze was blowing. Leaves on the tree were shaking. Sahil was sitting in the courtyard, rolling balls of wet soil and shaping them into various toys. Then he felt hungry and went into the house. Mother made a dough from wheat flour and fried purees. While eating hot purees, his attention was drawn outside the window. It had started raining. There was lighting too. Sahil was enjoying his dinner in the dim light.
Answer:

1. Clock showing six o’clock time – It is a periodic change.
2. Sun was setting – A periodic change.
3. Breeze was blowing – A natural change.
4. Leaves shaking – A natural change.
5. Making toys from wet soil – Physical change.
6. Making dough from wheat flour – Physical change
7. Frying purees – Chemical change.
8. Raining – Natural change.
9. Lightning – Natural change.

Project:

Question a.
Visit a place where work like powder coating. spray painting is done. Make a note of the information you obtain.

Class 7 Science Chapter 13 Changes – Physical and Chemical Important Questions and Answers

Fill in the blanks and rewrite the sentences:

Question 1.
Burning of candle is a ………………. change.
Answer:
chemical

Question 2.
Cooking of vegetable is ………………. change.
Answer:
useful

Question 3.
A man painted his main gate made up of iron to prevent it from ………………. .
Answer:
rusting

Question 4.
Galvanization is a process used to prevent the rusting of ………………. .
Answer:
iron

Question 5.
Making sugar solution is a ………………. change.
Answer:
physical

Question 6.
A physical change is generally ………………. .
Answer:
temporary

Question 7.
Grinding of wheat grain changes its size, it is a ………………. .
Answer:
physical change

Question 8.
Iron benches kept in lawns and gardens get rusted. It is a change because a new ………………. is formed.
Answer:
chemical, product.

State whether the following statements are True or False. Correct and rewrite the false statement:

Question 1.
Iron and rust are the same substance.
Answer:
False, Rust is oxide of iron.

Question 2.
Iron pipes coated with zinc do not get rusted easily.
Answer:
True

Question 3.
Formation of manure from leaves is a physical change.
Answer:
False, it is a chemical change.

Question 4.
Cutting a log of wood into pieces is a chemical change.
Answer:
False, it is a physical change.

Question 5.
Digestion of food is a chemical change.
Answer:
True

Question 6.
Melting of wax is a chemical change.
Answer:
False, it is a physical change.

Question 7.
Dissolving sugar in water is physical change.
Answer:
True

Question 8.
Changes in which new substances are formed are called physical changes.
Answer:
False, they are called chemical change.

Question 9.
Breaking down of larger food particles into smaller particles is a chemical change.
Answer:
False, it is a chemical change.

Question 10.
Setting of curd is a physical change.
Answer:
False, it is a chemical change.

Question 11.
Heating of iron is a physical change.
Answer:
True

Question 12.
Cooking a vegetable is chemical change.
Answer:
True

Question 13.
Freezing water into ice is a chemical change.
Answer:
False, it is a physical change

Define the following.

Question 1.
Physical change:
Answer:
In a physical change the material may change shapes or forms but no new compounds are formed and change can generally be reversed by reversing the conditions.

Question 2.
Chemical change
Answer:
A chemical change produces a new substance having new and different properties and which cannot be reversed by reversing the conditions.

Question 3.
Periodic change
Answer:
Some changes occur again and again after . a definite interval of time, such changes are called periodic changes.

Question 4.
Non-periodic change
Answer:
Changes that do not repeat themselves after a fixed interval of time are called non-periodic changes.

Question 5.
Reversible change
Answer:
The changes that can occur in a forward and reverse direction again and again are called reversible changes.

Question 6.
Irreversible change.
Answer:
The changes which we cannot reverse back to same thing are called Irreversible changes e.g. Burning of wood, paper.

Question 7.
Condensation
Answer:
The process by which matter changes from its vapour or gaseous state into its liquid state by cooling is called condensation.

Question 8.
Corrosion of metals
Answer:
When an iron article rusts, a reddish brown layer (of iron oxide) forms on it. A greenish layer is seen to form on a copper article. This is called corrosion of metals.

Question 9.
Galvanization
Answer:
Iron articles are given a thin coat of zinc to prevent corrosion this is called galvanization.

Question 10.
Tinning
Answer:
Copper and brass articles are coated with tin. This is called tinning.

Question 11.
Natural change
Answer:
Changes that occur naturally like ripening of a fruit, spoiling of milk are called natural changes.

Question 12.
Man-made change
Answer:
Man-made changes are result of human- activity. E.g. Burning of fossil fuel.

Question 13.
Useful change
Answer:
Many changes such as baking bread, cooking food are useful to us, they are called useful changes.

Question 14.
Harmful change
Answer:
The changes that are not useful or changes that harms living things or the environment are called harmful changes.

Name or Give two example of:

Question 1.
Two physical changes.
Answer:

1. Melting of wax
2. Melting of ice

Question 2.
Two chemical changes.
Answer:

1. Burning of wax candle
2. Burning of wood or paper.

Question 3.
Two periodic changes.
Answer:

1. Occurrence of day and night
2. change of seasons

Question 4.
Two non-periodic changes.
Answer:

1. A meteor moving across the sky.
2. A bird sitting on a tree flies away.

Question 5.
Two reversible changes.
Answer:

1. Melting of wax.
2. Freezing water into ice.

Question 6.
Two irreversible changes.
Answer:

1. Ripening of a mango.
2. Burning of wood

Question 7.
Two natural changes.
Answer:

1. Lighting in the sky.
2. Earthquake.

Question 8.
Two manmade changes.
Answer:

1. Baking bread
2. Cooking food.

Question 9.
Two useful changes.
Answer:

1. Ripening of mango
2. Curdling of milk.

Question 10.
Two harmful changes.
Answer:

1. Spoiling of milk.
2. Air pollution.

Match the following:

Question 1.

Column ‘A’	Column ‘B’
1. Photosynthesis	a. Physical change.
2. Dissolving sugar in water	b. Chemical change
3. Burning of wood	c. Man-made change.
4. Melting of wax	d. Periodic changes.
5. Digestion of food	e. Non-periodic change
6. Heartbeat	f. Chemical change.
7. Occurrence of earthquake.	g. Physical change.
8. Deforestation	h. Chemical change.

Answer:

Column ‘A’	Column ‘B’
1. Photosynthesis	b. Chemical change
2. Dissolving sugar in water	a. Physical change.
3. Burning of wood	f. Chemical change.
4. Melting of wax	g. Physical change.
5. Digestion of food	h. Chemical change.
6. Heartbeat	d. Periodic changes.
7. Occurrence of earthquake.	e. Non-periodic change
8. Deforestation	c. Man-made change.

Question 2.

Column ‘A’	Column ‘B’
1. Depositing a layer of zinc on Iron	a. Tinning
2. Souring of milk	b. Rust
3. Curdling of milk	c. Galvanization
4. Iron oxide	d.  Chemical changes
5. Depositing layer of tin on copper and brass article.	e. Man-made changes.

Answer:

Column ‘A’	Column ‘B’
1. Depositing a layer of zinc on Iron	c. Galvanization
2. Souring of milk	d.  Chemical changes
3. Curdling of milk	e. Man-made changes.
4. Iron oxide	b. Rust
5. Depositing layer of tin on copper and brass article.	a. Tinning

Distinguish between the following.

Question 1.
Reversible change and Irreversible change
Answer:

Reversible change	Irreversible change
1. The changes that can occur in a forward and reverse direction again and again is called reversible.	1. The changes which we can not reverse back to some thing are called irreversible change.
2. E.g.: (a) Melting a wax candle and obtaining the original solid wax again, (b) Stretching a rubber or spring.	2. E.g.: Burning of paper or wood cannot be undone. Wood cannot be obtained from the ash.

Under which different types can be following changes be classified:

Question 1.
Formation of curd from milk.
Answer:
Manmade change (useful), chemical

Question 2.
Burning of wood or paper.
Answer:
Manmade, chemical change.

Question 3.
Glowing of bulb.
Answer:
Manmade (fast).

Question 4.
Rusting of iron.
Answer:
Chemical change (harmful)

Question 5.
Burning of Camphor.
Answer:
Chemical change

Question 6.
Souring of milk.
Answer:
chemical change (harmful)

Question 7.
Digestion of food.
Answer:
Chemical change (useful), irreversible

Question 8.
Change of season.
Answer:
Periodic change, natural change

Question 9.
Day and night formation.
Answer:
Periodic change

Question 10.
Heartbeat.
Answer:
Periodic change

Question 11.
Water pollution.
Answer:
Manmade, harmful change

Question 12.
Air pollution.
Answer:
Manmade, harmful change

Question 13.
Burning of fossil fuel
Answer:
Manmade (irreversible change)

Question 14.
Ripening of fruit.
Answer:
Natural, chemical

Question 15.
Change-in climate.
Answer:
Natural, periodic

Question 16.
Melting of ice into water
Answer:
Physical change

Question 17.
Germination of seed.
Answer:
Natural, slow, desirable.

Question 18.
Bursting of balloon.
Answer:
Irreversible change (fast).

Give reasons:

Question 1.
The burning of wax is a chemical change
Answer:

1. Because when the cotton wick embedded in the candle is burnt, ash and smoke is formed.
2. It is not possible to make wick again from the smoke and ash.

Can you tell?

Answer the following questions:

Question 1.
We see many man-made materials in our day-to-day life. For what purpose are they produced.
Answer:
We see many man-made matrical in our day to day life. For example,

1. Air conditioners for getting cool air in houses offices and cars.
2. Wooden furniture made from wood obtained by cutting trees.
3. Refrigerators to protect food from spoiling.

Question 2.
You made a link from the glass piece. How will you change the shape of the link to give it its original shape?
Answer:
Heat the glass piece again at the link. When it becomes soft break it.

Question 3.
How will you restore the original candle after melting one ?
Answer:
Collect the melted wax and give the required shape when it is soft.

Question 4.
What comes after daytime?
Answer:
Night time (periodic change)

Question 5.
What is the next stage after sunrise?
Answer:
Sunset (periodic change)

Question 6.
What comes after a high tide in the sea?
Answer:
Low tide (periodic)

Question 7.
A bird sitting on a tree flies away.
Answer:
non-periodic change.

Question 8.
A meteor streaking across the sky.
Answer:
non-periodic change.

Use your brainpower!

Answer the following questions:

Question 1.
What kind of change is the falling of a tree in a storm?
Answer:
Natural change.

Question 2.
What kind of a change is the conversion of milk into yoghurt?
Answer:
Manmade ‘ change, useful change and a chemical change

Question 3.
What is meant by irreversible change? Give some examples.
Answer:

1. An irreversible change is a permanent change that cannot be undone, cannot reverse it back to original substance.
2. In irreversible change new materials are always formed.
3. Irreversible changes are permanent changes.
4. Heating, burning, mixing, powdering are few processes which causes irreversible changes.

Examples:

• burning of paper or wood
• cooking of raw egg.

Question 4.
Which type of change is the change of seasons from summer to rains to winter?
Answer:
Natural and periodic change

Question 5.
Which hands of a clock show periodic changes from 6.00 am to 6.00 pm? How many times?
Answer:
Small (hour) hand (12 times).

Question 6.
Which of the following are physical changes and which are chemical changes?
(making a table from wood, burning wood, breaking of a glass object, ripening of a tomato, rusting of iron.
Answer:

Physical	Chemical
1. Making a table from wood	1. Burning wood
2. Breaking of a glass object	2. Rusting of iron
	3. Ripening of a tomato

Question 7.
What are periodic and non-periodic changes?
Answer:
1. We find that some changes occur again and again after a definite interval of time. Such changes are called Periodic changes, e.g. Sunrise and Sunset.
2. On the other hand, it cannot be ‘Slid for sure when certain changes will recur after one occurrence. Even if they recur, the time interval is not fixed. Such changes are called non-periodic changes, e.g. A meteor streaking across the sky.

Question 8.a.
Which changes shown in the pictures below are temporary.

Answer:
(b) Removing iron nails with help of magnet
(d) Conversion of ice cubes into water.

Question b.
Which of the changes are permanent?
Answer:
Bud blooming into flower.

Question c.
In which did the original matter undergo a change?
Answer:

1. In permanent change
2. Bud blooming into flower.

Question d.
In which the original matter remain unchanged?
Answer:
In temporary changes
(b) iron nails
(d) ice cubes.

Question e.
In which of the changes was a new substance with a new property formed?
Answer:

1. Bud blooming into flower.
2. Ice to water, Ice is in solid state, Water is in liquid state.

Question 9.
Give some examples of fast and slow changes that occur in your surroundings.
Answer:

Fast	Slow
1. Burning of paper or wood	1. rusting of iron
2. Burning of candle	2. germination of seeds
3. Bursting of a balloon	3. curdling of milk
4. Bursting of crackers	4. ripening of a fruit

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 1 The Living World: Adaptations and Classification Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Science Solutions Chapter 1 The Living World: Adaptations and Classification

Class 7 Science Chapter 1 The Living World: Adaptations and Classification Textbook Questions and Answers

1. Find my match!

Question a.

Column ‘A’	Column ‘B’
1. Lotus	a. Flower and leaves attract insects
2. Aloe	b. Haustorial roots for absoption of food
3. Cuscuta	c. Adapted to live in deserts
4. Venus fly trap	d. Adapted to live in water

Answer:

Column ‘A’	Column ‘B’
1. Lotus	d. Adapted to live in water
2. Aloe	c. Adapted to live in deserts
3. Cuscuta	b. Haustorial roots for absoption of food
4. Venus fly trap	a. Flower and leaves attract insects

2. Read the paragraph and answer the following questions:

I am a penguin. I live in polar region covered by snow. My abdomen is white. My skin is thick with a layer of fat underneath. My body is spindle-shaped. My wings are small. My toes are webbed. We live in flocks.

Question a.
Why is my skin white and thick and why is there a thick layer of fat underneath?
Answer:

1. White skin colour camouflage with the snow so penguins cannot be easily spotted and they get protected from enemies.
2. Thick skin and thick layer of fat underneath gives them protection from severe cold.

Question b.
Why do we live in flocks sticking close to each other?
Answer:
Penguins live in flocks sticking close to each other because sticking close to each other reduce the relative area so there is least loss of heat and they get protection from cold.

Question c.
Which geographical region do I inhabit? Why?
Answer:

1. Penguins inhabit Antarctica region. Antarctica is surrounded by ocean. Climate is colder, drier and windier.
2. It does not have human population. This climate is suitable for penguins, so they inhabit Antarctica.

Question d.
Which adaptations should you have to enable you to live permanently in the polar region? Why?
Answer:

1. I should be a warm blooded animal. This should allow me to permanently live in polar region.
2. My body has to be covered with thick fur or scale so that loss of heat will be very less and I can survive in severe cold.

3. Who is lying?

Question a.
Cockroach – I have five legs.
Answer:
Cockroach is lying. It has six legs.

Question b.
Hen – My toes are webbed.
Answer:
Hen is lying because hen’s toes are not webbed. Duck has webbed toes.

Question c.
Cactus – My fleshy, green part is a leaf.
Answer:
Cactus is lying. It’s fleshy, green part is a stem not a leaf.

4. Read each of the following statements. Write a paragraph about adaptation with reference to each statement.

Question a.
There is extreme heat in deserts.
Answer:

1. Plant’s stem is fleshy, leaves get modified into thorns to reduce loss of water. Steam perform photosynthesis in the absence of leaves.
2. Animals have cushioned soles, hump, long legs and nostrils are protected by folds of skin. Eyelashes are long and thick.

Question b.
Grasslands are lush green.
Answer:
Insects like grasshoppers have green colour so they can be camouflaged amidst grasses.

Question c.
We hide.
Answer:
In equatorial region grasses are very tall, so to protect themselves animals like tiger, elephants and deer remain hidden in these tall grasses.

Question d.
We have long ears.
Answer:
It helps the animals to receive sounds from long distance, and they can protect themselves from predators.

5. Answer the following:

Question a.
Why is the camel called the ‘ship of the desert’?
Answer:

1. Camel lives in a desert easily due to following adaptations. It has long legs and cushioned soles which keep the body of camel above the sand and cushioned soles do not allow to sink in sand while walking.
2. The nostrils are protected by folds of skin.
3. The eyelashes are long and thick.
4. It has hump which stores fats so it helps camel to survive in desert for many days without food and water.

Due to above adaptations camel is used to carry people and transport goods from one place to another place in the desert. Therefore, camel is called the ship of the desert.

Question b.
How can the plants like cactus and acacia live in deserts with scarce water?
Answer:
The plants like cactus and acacia live in deserts with scarce water due to the following adaptations.

1. Leaves are like small needles or have been modified into thorns, as a result they lose very little water by evaporation.
2. The stem stores water and food so it is fleshy.
3. The stems are green as they perform photosynthesis in the absence of leaves.
4. Their roots penetrate deep into the soil in search of water.
5. There is a thick layer of a waxy substance on the stems.

Question c.
What is the inter-relationship between adaptations of organisms and their surroundings?
Answer:
1. Adaptations of organisms depend on the changes in the surroundings.

2. To adjust with those changes in the surroundings adaptation takes place gradually and continuously in organisms.

3. Changes that take place in the various organs and life processes of organisms, enable them to live, feed, reproduce to perpetuate themselves and to protect themselves from their enemies in specific surroundings, depending upon the habitat and its geographical conditions, are called adaptations.

Question d.
How are organisms classified?
Answer:

1. Different scientists have used different criteria and independently classified plants and animals.
2. A hierarchy is formed in the classification that starts with kingdom Animalia or kingdom Plantae, further groups and sub-groups are formed depending upon basic similarities and differences.
3. This is called the ‘hierarchy of classification’.
4. Binomial nomenclature is used to identify each organism. Accordingly, a scientific name has been assigned to each organism.
5. It consists of two parts – first part is ‘genus’ and second ‘species’.
6. All identified organisms have been assigned a binomial name as per the guidelines of the International code of Nomenclature. For e.g.

	Genus	Species
Mango	Mangifera	Indica
Human	Homo	Sapiens

Activity:

Question 1.
Find out how the gradual adaptation from primitive man to modern man must have taken place.

Class 7 Science Chapter 1 The Living World: Adaptations and Classification Important Questions and Answers

Fill in the blanks.

Question 1.
Leaves of some aquatic plants are …………. and …………. ike a ribbon.
Answer:
thin, slender

Question 2.
…………. in stems and …………. of aquatic plants are useful for floating in water.
Answer:
Air spaces, petioles

Question 3.
Leaves of desert plants are modified into …………. .
Answer:
thorns

Question 4.
The stems of desert plants are green as they perform …………. in the absence of leaves.
Answer:
photosynthesis

Question 5.
…………. roots of grasses prevent soil erosion.
Answer:
Fibrous

Question 6.
Grasses in the …………. region are very tall.
Answer:
equatorial

Question 7.
…………. are found in hilly areas as well as plains.
Answer:
Vast meadows

Question 8.
Plants need …………., …………. and …………. for growth.
Answer:
nitrogen, phosphorus, potassium

Question 9.
Dodder has …………. roots for absorbing nutrients from the host plant.
Answer:
haustorial (sucking)

Question 10.
Fungi do not have …………. so cannot perform photosynthesis.
Answer:
chlorophyll

Question 11.
Fish breathe with …………. instead of a nose.
Answer:
gills

Question 12.
Fish have …………. within the body to help them to float.
Answer:
air bladders

Question 13.
Frog and duck have …………. toes.
Answer:
webbed

Question 14.
Tigers have …………. paws.
Answer:
padded

Question 15.
Bats can fly with the help of …………. .
Answer:
patagium.

Question 16.
Desert plants are either leafless or their leaves are like …………. or modified into …………. .
Answer:
needles, thorns

Question 17.
Spring like …………. on the stems of some climbers are examples of their adaptation.
Answer:
Tendrils

Question 18.
…………. is not a sudden process, it is gradual and continuous.
Answer:
Adaptation

Question 19.
…………. proposed the theory of the survival of the fittest.
Answer:
Charles Darwin

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
1. Cactus	a. Herbivorous animal
2. Pine	b. Carnivorous animal
3. Tiger	c. Snowy region plant
4. Blackbuck	d. Desert plant

Answer:

Column ‘A’	Column ‘B’
1. Cactus	d. Desert plant
2. Pine	c. Snowy region plant
3. Tiger	b. Carnivorous animal
4. Blackbuck	a. Herbivorous animal

Question 2.

Column ‘A’	Column B’
1. Dog	a. Hibiscus roso sinensis
2. Cow	b. Sorghum bicolor
3. Hibiscus	c. Bos taurus
4. Jowar	d. Canis lupus familiarise

Answer:

Column ‘A’	Column B’
1. Dog	d. Canis lupus familiarise
2. Cow	c. Bos taurus
3. Hibiscus	a. Hibiscus roso sinensis
4. Jowar	b. Sorghum bicolor

Name the following:

Question 1.
Animals which live in desert in deep burrows.
Answer:
Rats, snakes, spiders, lizards

Question 2.
Animals which have webbed feet.
Answer:
Frog, duck

Question 3.
Plants of snowy regions.
Answer:
Deodar, pine

Question 4.
Plants that eat insects.
Answer:
Drosera, venus flytrap, pitcher plant

Question 5.
World Frog Protection Day.
Answer:
29th April

Question 6.
2 parts of bionomial nomenclature.
Answer:
genus and species.

Who am I?

Question 1.
My leaves trap insects.
Answer:
Venus fly trap or pitcher plant.

Question 2.
I have waxy feathers and webbed feet.
Answer:
Duck

Question 3.
I breath through skin in water and through lungs on land.
Answer:
Frog

Question 4.
I have sucking roots through which I take nutrition from my host plant.
Answer:
Dodder (cuscuta)

Question 5.
I have silvery white body with thick long hair
Answer:
Snow animals like polar bear.

Question 6.
I have waxy broad leaves and air spaces in my stem.
Answer:
Lotus (or aquatic plants)

Question 7.
My Scientific name is Bos taurus.
Answer:
Cow

Question 8.
I discovered Binomial nomenclature.
Answer:
Carl Linnaeus

Question 9.
I have special thin folds in between my forelegs and hind legs called patagium.
Answer:
Bat

Question 10.
I am mango, my genus is?
Answer:
Mangifera

Say whether true or false, correct and rewrite the false statements:

Question 1.
Killing or harming frogs is prohibited by the Wild Life Protection Act.
Answer:
True

Question 2.
Scientific name of jowar is Bos taurus.
Answer:
False. Scientific name of jowar is Sorghum bicolor

Question 3.
Theory of natural selection was found by Charles Darwin.
Answer:
True

Question 4.
T.V. Channels like National Geographic, Wild and Discovery show about the feeding habits of animals.
Answer:
True

Question 5.
The spindle shaped body of birds maximizes the resistance of air while flying.
Answer:
False. The spindle shaped body of birds minimises the resistance of air while flying.

Question 6.
House lizard and monitor lizards have webbed toes.
Answer:
False. House lizard and monitor lizards have clawed toes.

Question 7.
Crocodiles use their muscles for creeping.
Answer:
True

Question 8.
The eyes of predatory carnivores are located on either side of the head.
Answer:
False. The eyes of predatory carnivores are located in the front of their head.

Question 9.
A frog is an amphibian.
Answer:
True

Question 10.
Diverse types of bushes and grasses are found in the grasslands.
Answer:
True.

Complete the given table:

Question 1.

Question 2.
Give one special adaptation or features of the following plant or animal to suit its habitat surrounding
Answer:

Plant/animal	Special adaptation/features
1. Fish	Stream lined body
2. Bird	Hollow bones, feathers
3. Camel	Thick skin, folds in skin near nosetrils
4. Deer	long and tapering legs with strong hooves
5. Tiger	Padded paws, sharp canine teeth
6. Duck	waxy feathers, webbed toes
7. Fungi	Root like fibers
8. Cuscuta	Leafless, yellow thread like stem with haustorial (sucking) roots
9. Venus fly trap	Trigger hair inside their traps
10. Deodar tree	Conical shape and needle shaped leaves
11. Grape vine	Tendrils for support
12. Acacia	Fleshy thick green stem with leaves turned into thorns.

Who is lying?

Question 1.
Camel has thin skin and short eyelashes.
Answer:
Camel is lying – It has thick skin and long and thick eyelashes.

Answer in one or two sentences:

Question 1.
What is called ‘hierarchy of classification’?
Answer:

1. A hierarchy is formed in the classification that starts with kingdom Animalia or Kingdom Plantae, further groups and sub-groups are formed depending upon basic similarities and differences.
2. This is called the ‘hierarchy of classification’.

Question 2.
What theories were proprosed by Charles Darwin
Answer:
The theories of Charles Darwin are Theory of natural selection and theory of survival of the fittest.

Question 3.
Explain the terms Autotrophic and Parasitic
Answer:
1. Plants which are able to produce their own food with the help of the process of photosynthesis are called autotrophic plants eg. All green plants.

2. Plants which are not able to produce their own food but depend upon other plants for their nutrition are called parasitic plants They are leafless and non green in colour eg. Dodder (cuscuta). They have haustorial (sucking) roots for absorbing nutrients from the host plant.

Give scientific reasons:

Question 1.
Leaves of some aquatic plants are thin and slender like a ribbon.
Answer:
Leaves of some aquatic plants are thin and slender like a ribbon because this shape helps them to withstand fast currents of water.

Question 2.
Some aquatic plants have air spaces in stems.
Answer:
Some aquatic plants have air spaces in stems because air spaces help the plants to float on water.

Question 3.
Desert plants have thorns.
Answer:

1. Desert plants have thorns because in deserts, due to scarcity of water these plants are either leafless or their leaves are like small needles or modified into thorns.
2. They lose very little water by evaporation due to little surface area. This helps plants to survive in desert.

Question 4.
Desert plants have green stem.
Answer:
Desert plants have green stem because green stem performs photosynthesis in the absence of leaves.

Question 5.
Desert plants have strong roots.
Answer:
Desert plants have strong roots so they can penetrate deep into the soil in search of water.

Question 6.
Deodar tree is conical in shape.
Answer:
Deodar tree grows in snowy region and conical shape of the tree doesn’t allow snow to accumulate on the tree and thus protect the tree from snow.

Question 7.
Pine tree has thick bark.
Answer:
Pine tree grows in snowy region where it is extremely cold and its thick bark helps the tree to withstand the cold.

Question 8.
Plants in forest grow tall.
Answer:
In forest region variety of trees, shrubs and herbs are found. These plants compete amongst themselves for sunlight. Hence trees grow tall to get sunlight.

Question 9.
Cuscuta has haustorial roots.
Answer:

1. Cuscuta is a parasitic plant. It is leafless and cannot prepare food on its own.
2. So to get food haustorial (sucking) roots penetrate up to the conducting vessels of the host plant to absorb water and food, the Cuscuta has haustorial roots.

Question 10.
Fungi have root-like fibers.
Answer:

1. Fungi are parasitic.
2. They do not have chlorophyll and cannot perform photosynthesis.
3. So these root-like fibers help to absorb the food from the starchy foodstuffs like bhakri and bread.

Question 11.
Pitcher plant eats insects.
Answer:

1. Pitcher plant grows in a soil where nitrogen, phosphorous and potassium are very less. But the plant needs these for the growth.
2. So to fulfill the need for nitrogen, pitcher plant consumes insects.

Question 12.
Duck and frog have webbed feet.
Answer:
When duck and frog are in water at that time the webbed feet act as oars and help them to swim in water.

Question 13.
Frogs can swim easily in water.
Answer:
Frogs have webbed toes, slippery, smooth skin and triangular head. This helps the frog to swim easily through water.

Question 14.
Tiger has sharp and pointed canine teeth.
Answer:
Tiger is a carnivorous animal. So the sharp and pointed canine teeth help the tiger to tear the prey and eat.

Question 15.
Blackbuck has eyes on either side of the head.
Answer:
Blackbuck is a herbivore animal and eyes on either side of the head gives them wide angle vision which helps to protect themselves from predators.

Question 16.
Tigers have padded paws.
Answer:
Tigers are carnivorous animals. So these padded paws enable them to silently stalk their prey and capture it easily.

Question 17.
The eyes of predatory carnivores are located in the front of their head.
Answer:
The eyes of predatory carnivores are located in the front of their head because it helps them to spot their prey from a long distance.

Question 18.
Camel can live in desert.
Answer:

1. Camel can live in desert because it has thick skin to prevent loss of water from the body. Their legs are long with flat and cushioned soles.
2. The nostrils are protected by folds of skin. The eyelashes are long and thick so these adaptations enable Camels to live in desert easily.

Question 19.
White fox has white body colour.
Answer:

1. White fox lives in snowy region which throughout the year is covered with snow.
2. White colour of fox matches with the snow so it gets camouflaged in snow and it can save itself from predators.

Question 20.
Birds can fly in the air.
Answer:

1. Birds can fly in the air because the spindle shaped body minimises the resistance of air while flying.
2. Their hollow bones, body covering of feathers and forelegs being modified into wings, their body being light in weight, all these factors make the birds adapted to fly in the air.

Can you tell?

Answer the following questions:

Question 1.
Arc the plants and animals from Kashmir and Rajasthan of the same type? Can you elaborate on any differences between the two?
Answer:
Plants and animals from Kashmir and Rajasthan are of different types.
Differences in plants:

1. Plants of Kashmir, which is a snowy region, are conical in shape due to their sloping branches.
2. This shape prevents the snow accumulation on the tree and the thick bark helps the tree to withstand the cold.
3. But the plants of Rajasthan, which is a desert region, are either leafless or their leaves are small, needle shaped or have been modified into thorns. So the loss of water can be reduced
4. The stem stores water and food so they are fleshy. The stem performs photosynthesis in the absence of leaves.

Differences in animals:

1. Animals of Kashmir have thick hair and white or silver body colour camouflaged with snow. This helps them to get protection in snowy region.
2. The animals of Rajasthan have long legs with flat and cushioned soles.
3. The nostrils are protected by folds of skin. The eyelashes are long and thick. It gives protection from sand and heat.

Question 2.
In what way are sloping branches useful to plants in a snowy region?
Answer:
In a snowy region sloping branches of a plant gives conical shape to the tree and it doesn’t allow snow to accumulate on tree inspite of heavy snowfall and thus protect the tree from severe cold and snow.

Question 3.
What is the main difference between vehicles on the road and aeroplanes?
Answer:
The two main differences between vehicles on the road and aeroplanes are:

1. aeroplanes have wings whereas vehicles on the road do not have wings.
2. The body of aeroplanes are spindle shaped and the body of vehicles on the road depends on the number of wheels they have.

Use your brain power!

Answer the following questions:

Question 1.
Why does water trickle off lotus leaves?
Answer:

1. Water trickles off lotus leaves because it is coated with waxy covering on it.
2. It is one of the adaptations of aquatic plants to survive in water without getting wet and rot or sink to the bottom.

Question 2.
Why don’t the leaves of lotus plants rotinwatei?
Answer:
leaves of these plants do not rot in water because it is covered with waxy coating on it so that they do not get wet.

Question 3.
Why are roots of lotus plants short and fibrous?
Answer: –

1. These plants grow in water so the roots do not need to go deep down in search of water. Their roots are not anchored in the soil.
2. So their roots are short and fibrous.

Question 4.
The lotus stalk has holes or air spaces?
Answer:

1. The air spaces in stems and petioles of aquatic plants are useful for making them float in water and also to prevent them from rotting
2. Hence, the lotus stalk has holes or air spaces.

Answer in detail:

Question 1.
Explain the Darwin’s theory of evolution.
Answer:
Charles Darwin, a biologist suggested two principles in his theory of evolution.

1. Theory of survival of the fittest: He said that only those organisms are likely to survive which can best adapt themselves to a changing environment. This is called the theory of survival of the fittest.
2. Theory of ‘Natural selection’: If an organism is bom with a new beneficial characteristic and is able to survive, this change is preserved in the next generation. This is called the theory of ‘natural selection’.

Diagram based questions:

Draw a neat labelled diagram of fish and answer the following questions.
Answer:

Question a.
Why do fish have a body tapering towards both its ends?
Answer:
Fish have its body tapering towards its ends, to allow them to swim with least resistance in water.

Question b.
Why do Fish have transparent eyelids.
Answer:
The transparent eyelids of fish protect the eyes from the substance in the water

Question c.
How are they able to float?
Answer:
Fish have air bladders within their body which help them to float.

Observe the diagram and answer the questions.
Answer:

Question a.
What habitat does this camel live in?
Answer:
Camel lives in desert habitats or in areas where there is scarcity of water.

Question b.
State any 2 of its body adaptations to survive in desert?
Answer:

1. Thick skin to prevent loss of water from the body
2. The eyelashes are long and thin
3. Their legs are long and flat with cushioned soles

Question c.
How does a camel protect itself from sand storms or winds carrying sand?
Answer:
Camels have nostrils protected by folds of skin and long thick eyelashes to prevent entry of fir dust and sand into its nose and eyes.

Paragraph based questions:

Compare and contrast:

Question 1.
Compare the lotus plant to the Acacia plant and Hibiscus plant.
Answer:

Lotus plant	Hibiscus plant	Acacia plant
I. Stem have air spaces in them	Stem do not have air spaces and do not store too much of water and food	Stem is fleshy and stores water and food
ii. Leaves have a waxy coating	Leaves do not have a waxy coating and have thin lamina	Leaves are not present and if present are very tiny or modified into thorns

Question 2.
What is the difference between the plants given in the pictures. Give 2 points of difference taking into consideration their adaptations with their surroundings.

Answer:

A. Cactus	B. Lotus	C. Deodar tree
i. Stem is green and fleshy	Stem is with air space	Shape of tree is conical
ii. leaves are reduced or absent and replaced by thorns	Leaves are broad and with a waxy coating	Leaves are needle shaped

Balbharti Maharashtra State Board Class 7 History Solutions Chapter 11 Marathas – The Protectors of the Nation Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 History Solutions Chapter 11 Marathas – The Protectors of the Nation

Class 7 History Chapter 11 Marathas – The Protectors of the Nation Textbook Questions and Answers

1. Name them:

Question 1.
They came from Afghanistan.
Answer:
The Pathans

Question 2.
They settled at the foothills of the Himalayas.
Answer:
The Rohillas

Question 3.
The brother of Nanasaheb Peshwa.
Answer:
Raghunathrao

Question 4.
The chief of Jats at Mathura.
Answer:
Surajmaljat

Question 5.
Defeated the Nizam at Rakshasbhuvan near Paithan.
Answer:
Madhavrao

2.Write in brief about:

Question 1.
Raising the Maratha standard at Attack. Or Hoisting the Maratha standard at Attack.
Answer:

• Najib Khan, the Rohillas chief could not tolerate the Maratha supremacy.
• Najib Khan requested Abdali to invade India again. He captured Delhi.
• He returned to Afghanistan and collected huge wealth.
• Raghunathrao and Madhavrao Holkar marched to the North and captured Delhi.
• They defeated Abdali’s officers and captured Punjab.

Question 2.
Conflict with the Afghans.
Or
Battle with the Afghans.
Answer:

• In CE 1751, Ahmadshah Abdali conquered Punjab.
• Due to that, the Mughals were facing threat from Abdali.
• So they joined hands with the Marathas to protect Delhi.
• The Emperor signed a treaty with Marathas in 1752.
• As per the treaty, the Marathas agreed to protect the Mughal Empire.
• The Maratha army marched towards Delhi.
• As Abdali got this news, he returned to his native country (Afghanistan).
• Due to the Maratha power, the threat of Abdali got subsided.

Question 3.
The after effects of the battle of Panipat.
Answer:

• The Marathas were defeated.
• The whole generation of Marathas were killed.
• Many brave soldiers died on the battlefield.
• It caused a great harm to the reputation of Marathas in Northern India.

3. Arrange chronologically:

• The battle of Rakshasbhuvan
• The death of Tipu Sultan
• The death of Madhavrao Peshwa
• The battle of Panipat
• The battle of Buradi Ghat

Answer:

• The battle of Buradi Ghat
• The battle of Panipat
• The battle of Rakshasbhuvan
• The death of Madhavrao Peshwa
• The death of Tipu Sultan.

4. Find the names of people in the chapter :

Question 1.
N _ n _ _ _ _ _ _
Answer:
Nanasaheb

Question 2.
D _ _ _ _ _ _
Answer:
Dattaji

Question 3.
N _ _ _ _ _ _ _ _
Answer:
Nizamshah

Activity:

Find more information about the battle of Panipat on the internet and make a presentation in your class.

Class 7 History Chapter 11 Marathas – The Protectors of the Nation Additional Important Questions and Answers

Complete the sentence by choosing the appropriate word from the options given below:

Question 1.
Ahmadshah Abdali was the Emperor of ______. (Mysore, Paithan, Afghanistan)
Answer:
Afghanistan

Question 2.
The chief of the Maratha artillery was ____. (Ibrahim khan, Hyder Ali, Najib Khan)
Answer:
Ibrahim khan

Question 3.
The Marathas defeated _________ in a battle at Motitalao near Srirangapattan. (Hyder Ali, Ibrahim Khan, Abdali)
Answer:
Hyder Ali

Question 4.
Safadarjung was the Nawab of ______.(Mysore, Paithan, Ayodhya)
Answer:
Ayodhya

Question 5.
_____ the ruler of Afghanistan conquered Punjab in 1751 CE. (Ahmadshah Abdali, Rohillas, Hyder Ali)
Answer:
Ahmadshah Abdali

Question 6.
Nanasaheb sent ________ to the North to crush Abdali. (Sadashivraobhau, Surajmal Jat, Vishwasrao)
Answer:
Sadashivraobhau

Question 7.
Hyder Ali usurped the throne of _____ (Mysore, Paithan, Ayodhya)
Answer:
Mysore

Question 8.
______was a Rohilla chief. (Ibrahimkhan, Najibkhan, Ahmadshah)
Answer:
Najibkhan

Question 9.
Madhavrao defeated the Nizam at ______ near Paithan. (Srirangapattan, Rakshasbhuvan, Buradi Ghat)
Rakshasbhuvan

Question 10.
After the death of Peshwa Nanasaheb, his son ________ succeeded him. (Bajirao II, Madhavrao, Vishwasrao)
Answer:
Madhavrao

Match the following:

Question 1.

Column ‘A’	Column ‘B’
(1) The Nawab of Ayodhya	(a) Raja Sawal Jaysingh.
(2) The Rohilla Chief	(b) Safadarjung
(3) The Chief of the Jats	(c) Najib Khan
(4) The chief of the Maratha artillery	(d)  Surajmal (e)  Ibrahim Khan Gardi

Answer:
1 – b
2 – c
3 – d
4 – e

Find the name of people in the chapter:

Question 1.
I _ _ _ h _ _ _ _ _ _
Answer:
Ibrahimkhan

Name them:

Question 1.
He met a heroic death in the battle.
Answer:
Dattaji

Question 2.
He became Peshwa after Bajirao.
Answer:
Nanasaheb

Question 3.
They do not help Marathas in the Battle of Panipat.
Answer:
Jats and Rajputs

Question 4.
The army of the Marathas attacked Abdali on 14th January, 1761.
Answer:
Battle of Panipat

Question 5.
The Sultan who took advantage of the defeat of the Marathas at Panipat and attacked the Maratha territory in Karnataka.
Answer:
Sultan Hyder Ali

Question 6.
The death of this capable Peshwa caused a great loss to Maratha Kingdom.
Answer:
Peshwa Madhavrao

Question 7.
Understood that only Marathas can rule over the chaos in North and wished that Marathas should rule the North.
Answer:
Abdali and his heirs

Answer the following in one sentence:

Question 1.
Why did the Peshwa send Dattaji Shinde and Janakoji Shinde to the North?
Answer:
The Peshwa sent Dattaji Shinde and Janakoji Shinde to crush the power of Najibkhan and to get a firm hold over the Punjab.

Question 2.
Why did the Nawab of Ayodhya invite the Marathas?
Answer:
The Nawab invited the Marathas to subdue the Rohillas.

Question 3.
Who helped the wounded Maratha soldiers in the Panipat battle?
Answer:
Surajmal Jat, Queen Kishori helped the wounded Maratha soldiers in the Panipat battle.

Question 4.
When did the third battle of Panipat start?
Answer:
The Marathas attacked Abdali on 14th January, 1761 and the third battle of Panipat started.

Question 5.
What conditions were laid in the treaty signed between the Emperor and the Marathas in April 1752?
Answer:
According to this treaty, the Marathas agreed to protect the Mughal Empire from enemies like the Rohillas, Jats, Rajputs and Afghans, etc. In return, the Marathas got cash and the rights to collect Chauthai from a few regions of North (Punjab, Multan, Rajputana, Sindh and Rohilkhand).

Question 6.
With whom did Nanasaheb campaign against Abdali?
Answer:
Jayappa Shinde, Madhavrao Holkar along with Nanasaheb campaigned against Abdali.

Question 7.
Why did Hyder Ali attack Marathas when they were defeated at Panipat and they had become weak?
Answer:
Hyder Ali thought that the Marathas were defeated at Panipat and they had become weak and so he attacked them.

Question 8.
In which battle did the Marathas defeat Hyder Ali?
Answer:
In the battle at Moti Talav, near Srirangapattan

Question 9.
From where did the Pathans migrate and settle?
Answer:
The Pathans had migrated from Afghanistan and they settled near Ayodhya at the foot of the Himalayas.

Question 10.
How did the history of Maratha describe Madhavrao?
Answer:
Madhavrao is described as an honest, hardworking, determined and a caring administrator for the common people.

Answer in brief:

Question 1.
The battle of Panipat.
Answer:

• Sadashivraobhau captured Delhi.
• The third battle of Panipat started.
• The Marathas attacked Abdali on 14th January, 1761.
• A bullet hit Vishwasrao and he fell dead.
• When Sadashivraobhau heard this, he attacked the enemy in madness, and disappeared from the battlefield.
• The Maratha soldiers lost courage.
• Abdali with the reserve contingent attacked the Marathas.
• The Marathas got defeated.

Complete the following family tree of Peshwa:

Question 1.

Answer:

1. Balaji alias Nanasaheb
2. Raghunathrao
3. Madhavrao (Peshwa)
4. Sawai Madhavrao (Peshwa)

Question 2.
Find the name of people in the lesson in following grid:
Answer: