Bhagya

Std 8 Science Chapter 8 Pollution Question Answer Maharashtra Board

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

Class 8 Science Chapter 8 Pollution Question Answer Maharashtra Board

Class 8 Science Chapter 8 Pollution Textbook Questions and Answers

1. Following are some statements about pollution. Which type of pollution do those express:

Question a.
Fog seems to be appearing in Delhi during day hours.
Answer:
Air pollution-Smog
(The sentence should have the word Smog and not fog. Smog is fog with smoke. Only fog cannot be polluting, but the smog is.)

Question b.
Many times, vomiting and dysentery occurs after eating ‘panpuri’.
Answer:
Water pollution-Contaminated food and water due to bacteria or virus

Question c.
Problem of sneezing occurs sometimes during visit to garden.
Answer:
Air pollution due to pollens

Question d.
Crop does not grow up in some areas.
Answer:
Soil pollution

Question e.
People living in the busy squares face the problems like short breathing and other respiratory problems.
Answer:
Air pollution due to traffic

2. Read the passage and identify the sentences expressing types of pollution.

Question a.
Nilesh is a student of Std. VII and lives in urban area. It takes about an hour to go to the school by bus. He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school. He is facing the problem of asthma since last few days, Doctors recommended him to stay away from urban area. Since then, his mother sent him to the village of his maternal uncle, Nilesh saw the heaps of garbage at many places in village. Foul smell of human and animal wastes was present at many places. Blackish water with foul smell was flowing in a stream. He developed some abdominal disease within few days.
Answer:

1. It takes about an hour to go to the school. (Due to traffic jam, Nilesh is spending more time in polluted, contaminated air.)
2. He faces the heavy traffic. (Large scale combustion of fossil fuel.)
3. He is facing the problem of asthma. (Air pollution – Harmful to human health.)
4. The heaps of garbage at many places. (Solid waste – Land pollution.)
5. Foul smell of human and animal wastes. (Biological pollution, air pollution.)
6. Blackish water with foul smell was flowing in a stream. (Improper sewage management – Water pollution.)
7. He developed some abdominal disease within few days. (Water pollution – Effect on human health.)

3. Match the pairs from ‘A’ and ‘B’ columns and explain the effect of pollution on human health.

Question a.

Answer:

4. True or false.

Question a.
Water does not get polluted by washing the clothes in running water of river.
Answer:
False. (Even if washing of soiled clothes is done in running water, it will cause pollution as the dirt and the waste materials will be added to water. This certainly will cause water pollution.)

Question b.
More the use of electric appliances, more will be the pollution.
Answer:
True. (Most of the electricity is generated in India by burning coal. The power generation plants thus cause lots of air pollution. More the electricity is used by using more appliances, there will be more pollution. However, only power generation through solar energy cannot cause pollution.)

5. Answer the following:

Question a.
What is pollution?
Answer:
Contamination of natural environment that can harmfully affect the environment is called pollution.

Question b.
What are Pollutants?
Answer:
The products which affect the normal functioning of ecosystem and have an adverse effect on plants, animals and humans are called pollutants.

Question c.
What is acid rain?
Answer:
1. When rainwater contains harmful amounts of nitric and sulphuric acids, it is called acid rain.
2. Burning of fossil fuels such as coal, wood, petroleum, etc. releases nitrogen oxide and sulphur oxide into the atmospheric air.
3. Since these oxides are soluble in water, they dissolve in rainwater. Nitrogen and sulphur oxides dissolved in large quantities of water vapour form acids like nitric acid, nitrous acid, sulphurous acid and sulphuric acid.
4. These acids mix with mist, drops of rainwater and snow. They change their composition and fall back on the ground in the form of acid rain.
5. Effects of acid rain are as follows:

• Increase in the acidity of soil and water bodies.
• Damage to the trees.
• Water becomes unsuitable for fish and wildlife.
• Buildings, statues, sculptures, bridges, monuments and fences are corroded due to acid rain. Thus, acid rain damages our national assets.
• Acid rain affects agriculture and crop lands.

Question d.
What is greenhouse effect?
Answer:

1. Greenhouse effect is the ; phenomenon due to which global warming and climate change occur.
2. The earth receives solar energy in the form of heat from the sun. The surface of earth absorbs this heat and reflects it back to the atmosphere as infrared radiation. Some of this heat energy goes directly into space.

Question e.
Which are visible pollutants known to you?
Answer:
1. The polluting substances that are seen easily with the naked eyes can be called as visible pollutants. E.g. Solid wastes, plastic articles, plastic bags, the suspended things in the water, metal refuse, etc.

Question f.
Which are invisible pollutants?
Answer:
The pollutants which are completely dissolved in water or mixed in the air, cannot be seen and hence they can be called invisible pollutants. Since they are not seen, we remain unaware about the presence of these pollutants. E.g. the insecticides spread f on the crops. Aerosols, many hazardous gases in the air, toxic compounds that are totally soluble in water, etc.

6. Answer the following.

Question a.
Give two examples of each of water, soil and air pollution from your residential area.
Answer:
Air pollution:

1. New buildings are constructed. Old structures are demolished. This is creating lots of dust pollution. The air is full of particulate matter.
2. The number of vehicles on the road has tremendously increased. This causes smoky environment.

Water pollution:

1. The sea shows lots of floating plastic and decaying flowers, etc. When beaches are visited it is a common sight.
2. Many fishes are seen dying in great numbers and are washed off to the shore.

Soil pollution :

1. Everywhere garbage heaps are seen. In that plastic bags, needles, old medicine vials and cartons are seen in abundance.
2. The sludge brought by rainwater is spread everywhere and that causes stink.

Question b.
How does the pollution occur due to vehicles? Give the names of vehicles causing least pollution.
Answer:

1. More than 50% of the air pollution is caused by vehicular traffic.
2. Particulate matter, unburnt hydrocarbons, CO, nitrogen oxides and carcinogenic hydrocarbons are present in the automobile exhausts.
3. Fossil fuels like petrol, diesel, natural gas, gasoline, etc. which are burnt to run the automobiles lead to the emission of CO₂ and other gases.
4. Therefore, vehicles are said to be the major contributors to air pollution.
5. The only vehicle which is non¬polluting is bicycle. The four-wheelers which are battery operated are also manufactured recently.

These two types of vehicles are eco-friendly. The cars that run on C.N.G. are also said to be lesser polluting.

Question c.
What are natural reasons causes for water pollution?
Answer:
The natural causes of the water pollution:
1. If organic pollutants are added to the water there is an overgrowth of weeds such as Eichhornia. The growth of algae also makes the water unsuitable for consumption. These aquatic plants release oxygen during daytime but by night they require oxygen thus depleting the dissolved oxygen level. The natural characters of water are then changed.

2. The decomposing matter when added to the water make it polluted and stinking.

3. Due to deposition of sludge or eroded soil, the rivers change their path and divert from original flow. The currents are also changed. Deposition of sludge makes the water polluted.

4. Due to soil erosion, surrounding the water bodies, the microbes, bacteria, protozoans and the worms and larvae of nematodes enter the water causing severe biological pollution. Many inorganic pollutants are also added to the water. The fungand bacteria present in the water make it non-potable. Such water spreads water-borne diseases.

Question d.
Suggest four preventive measures for air pollution.
Answer:
The following methods are adopted to control air pollution from the industries:

1. The source discharge is diluted by tall chimneys.
2. There are source correction methods like changing the raw material, equipment modification, process modification, etc.
3. Effective pollution controlling equipment like dust collectors, electrostatic precipitators, wet scrubbers, etc. should be used.
4. There should be ban and control over atomic tests and chemical weapons on the international level.

Question e.
Explain relation between greenhouse effect and global warming.
Answer:
Because of greenhouse effect, there is increase in the global temperature. The heat on the earth remains trapped due to envelope of greenhouse gases. The percentage of carbon dioxide and methane is constantly increasing and hence there is increase in the temperature too. Thus the greenhouse effect is directly related to the global warming.
Effects of this relation between greenhouse effect and global warming are as follows:

1. The polar ice caps and the glaciers at both the poles are melting due to increased temperature.
2. The oceans’ water is rising due to this melted ice. The sea level rise is causing coastal land submergence. The islands at various regions are threatened of drowning.
3. Many species of living organisms are already extinct due to global warming. The rest are also threatened.
4. Wild animals are showing weird migrations. Polar bear is endangered.
5. The increased temperature of the oceanic water is causing many changes in the tides and currents. This results into increased occurrence of cyclones, hurricanes and cloud bursting. The natural disasters are rising in last decade.
6. The agricultural production is decreasing. The regions with less rainfall are facing draughts.

Question f.
Construct two slogans each on air, water and soil pollution.
Answer:
Air pollution:

1. Be a part of the solution and not part of pollution.
2. Show your care, clean your air.

Water pollution:

1. Water, water everywhere, Not a drop to drink. The pollution is making all the water stink.
2. Save the fish and the little turtle. Don’t throw plastic or it will encircle.

Soil Pollution:

1. Don’t be mean, keep environment clean.
2. Let’s keep land clean, together only we can win.

7. Classify the following pollutants into natural and manmade categories.

Question
Classify the following pollutants into natural and manmade categories.
Sewage, dust, pollen grains, chemical fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.
Answer:

Project:

Question 1.
Visit the water testing laboratory in your area and collect the information about tests for checking the purity of water.

Question 2.
Visit the square having heavy traffic in your area and report the pollution at different times of day and find out the duration of maximum pollution.

Class 8 Science Chapter 8 Pollution Additional Important Questions and Answers

Rewrite the sentences after filling the blanks:

Question 1.
Natural pollutants are destroyed in due course of time by …………. .
Answer:
Natural pollutants are destroyed in due course of time by nature’s rule.

Question 2.
Air pollutants with ……….. cause colour change in paints, oil paintings, nylon, etc.
Answer:
Air pollutants with sulphur cause colour change in paints, oil paintings, nylon, etc.

Question 3.
Boards indicating the …………. are displayed in busy squares in metro cities.
Answer:
Boards indicating the air quality index are displayed in busy squares in metro cities.

Question 4.
Soil ………… decreases due to pollution.
Answer:
Soil fertility decreases due to pollution.

Question 5.
Problem of …………… pollution increases due to soil pollution.
Answer:
Problem of water pollution increases due to soil pollution.

State whether the following statements are True or False. Explain your statement:

Question 1.
Polluted water is responsible for diseases such as cholera, hepatitis, typhoid, skin diseases and diseases of the alimentary canal.
Answer:
True. (The water sources if they are contaminated with biological pollutants such as bacteria, viruses or protozoans, can cause variety of water-borne diseases.)

Question 2.
When water is mixed with natural or artificial unwanted material, the dissolved oxygen level of such water increases.
Answer:
False. (When water is mixed with natural or artificial unwanted material, the dissolved oxygen level of such water decreases. This causes harm to the resident animals. However when aquatic weeds and algae outgrow in number it causes rise in oxygen only during day time.)

Question 3.
Though any amount of pollutants are added to the soil, the toxic substances do not leach into water.
Answer:
False. (The toxic substances added to the soil can leach in the groundwater and cause water pollution.)

Identify the odd term:

Question 1.
Industrialization, Population explosion, Mining, Vehicular transport, Dust storms.
Answer:
Dust storms (All others are man-made causes environmental degradation.)

Question 2.
Poisoning, asthma, Silicosis, respiratory diseases.
Answer:
Silicosis (All others are effects of methane.)

Question 3.
Irritation of eyes, respiratory tract, excess mucus, mental weakness
Answer:
Mental weakness (All other are effects of sulphur dioxide.)

Question 4.
Volcanic eruption, Earthquake, Atomic explosion, Forest fires.
Answer:
Atomic explosion (All others are natural causes of air pollution.)

Question 5.
Uranium, Sulphur, Thorium, Plutonium.
Answer:
Sulphur (All others are elements which are used in the production of atomic energy.)

Consider the relation between the items in the first pair and write the correlation for second pair:

Question 1.
Industrialization: Sulphur compounds : :…………………. : Lead compounds
Answer:
Use of fuels/Transportation

Question 2.
City where smoke and soot caused it to be called black city : Petersburg : : Indian city where worst ever industrial accident has occurred : ……………….
Answer:
Bhopal

Question 3.
Arsenic and Cadmium : Inorganic water pollutants : : Weedicides and insecticides : ………….
Answer:
Organic water pollutants.

Write definitions:

Question 1.
Air pollution.
Answer:
Contamination of air by toxic gaseous and particulate pollutants in concentration which is harmful to human beings and his surroundings is called air pollution.

Question 2.
Water pollution.
Answer:
When toxic and unwanted substances enter, dissolve or remain suspended in the water bodies deteriorating the quality of water and affecting the aquatic ecosystem, then it is known as water pollution.

Question 3.
Soil pollution.
Answer:
Soil pollution is the phenomenon caused due to natural or man-made causes, which occurs when there are changes in its physical, biological and chemical properties of the soil leading to decreased fertility due to either natural or man-made reasons.

Distinguish between the following:

Question 1.
Degradable and Non-degradable pollutants:

Question 2.
Industrial waste and Domestic waste:

Give scientific reasons:

Question 1.
Domestic sewage is harmful for all forms of life.
Answer:

1. Domestic sewage contains water
2. There are detergents and washing private vehicles. powders containing phosphate, which are used to soften the water.
3. These chemicals are harmful to aquatic animals.
4. They also contain disease. causing pathogenic bacteria and viruses.
5. Hence, domestic sewage is harmful for originating from kitchen, bathrooms, toilet, forms of

Question 2.
Use public transport instead of private vehicles.
Answer:

1. All the automobiles use fossil used to soften the water. fuels Burning of fossil fuels causes air pollution by gaseous pollutants as well as by particulates.
2. Toxic gases such as CO, CH₄, SO₂, etc. are emitted through automobile exhausts.
3. When each person uses private vehicles, the proportion of air pollution increases.
4. Instead, public transport helps to reduce air pollution it will also help to ease trafficams.
5. Therefore, as a role of citizen in pollution control, public transport should be used instead of private vehicles.

Question 3.
Due to agriculture, there can be a lot of air pollution.
Answer:

1. During agricultural practices, open field burning is done. Due to this burning there is emission of gases like SO₂, CO₂, CH₄, CO and oxides of nitrogen along with large amounts of particulate matter.
2. In agricultural practices, pesticides used emit toxic chemicals.
3. Industrial farms pollute air by emitting foul odour and airborne pollutants.
4. When manure is decomposed, there is production of greenhouse gases.

Question 4.
A hole has been observed in the ozone layer in the stratosphere near Antarctica.
Answer:

1. Ozone layer depletion is mainly caused due to the action of CFC (Chlorofluorocarbon) molecules in the air.
2. Due to various increased activities of humans, the magnitude of air pollution has been increasing in the last few decades.
3. CFC molecules were used as coolants in refrigerators, freezers and air conditioners.
4. They were also present in industrial solvents, dry cleaning agents and hospital sterilants, aerosols and foam. Due to such enhanced use, much of the CFCs were liberated in the last few years.
5. CFC molecules are decomposed by ultraviolet rays which release chlorine and fluorine molecules.
6. Chlorine and fluorine react with the ozone resulting in a hole in the ozone layer present in the stratosphere.

Therefore, a hole has been observed in the ozone layer in the stratosphere above Antarctica.

Answer the following.

Question 1.
What do you mean by ozone layer depletion? What are the causes of ozone layer depletion?
Answer:
1. The ozone layer is present at the top of the stratosphere. The stratosphere is the second layer of the atmosphere which is present 48 km above the earth’s surface.
2. Ozone layer is protective layer for living organisms of the earth, as it absorbs harmful UV rays from the sun. When this layer is reduced or destroyed, it is called ozone layer depletion.

3. Causes of the ozone layer depletion:

1. The main cause of ozone depletion are CFC molecules.
2. Chlorine atoms are present in chlorofluoro-carbons (CFC) molecules. They react with ozone and deplete it.
3. CFCs are used as coolants in refrigerators, freezers and air conditioners manufactured before 1995.
4. CFCs are also present in industrial solvents, dry cleaning agents and hospital sterilants (sterilizers), aerosols and foam. All the above materials release a lot of CFCs into the atmosphere.
5. CFC molecules are broken down by ultraviolet radiations which result in release of chlorine and fluorine, which further reduce the ozone layer.

Question 2.
What adverse effect does ozone depletion have?
Answer:

1. When the ozone layer is depleted, the ultraviolet radiations of the sun can reach the earth’s surface in greater proportion.
2. This results in damage to animal and plant life on the earth.
3. Ultraviolet rays cause skin cancer and cataract in human beings.
4. The ozone hole is seen in the stratosphere above Antarctica.

Question 3.
Describe the effects of air pollution on animals and plants.
Answer:
1. Effects of air pollution on animals:

• Air pollutants affect breathing of the animals.
• Particulate pollutants can cause problems to the wildlife.
• Particulate matter containing heavy metals is accumulated in the bodies of animals. The accumulated heavy metals at high levels in the body tissues, can cause problems. ‘
• Acid rain causes serious problems to animal life.

2. Effects of air pollution on plants:

• Various parts of the plant show reduced growth after coming in contact with air pollutants.
• The leaves show yellowing or chlorosis on exposure to air pollutants.

Question 4.
What are man-made reasons for water pollution?
Answer:
The effluents and other substances released by man into the surrounding water bodies together can be called man-made reasons for water pollution.
1. Domestic sewage: The excreta, urine and other domestic-use water is added to the water bodies in many cities and villages. In big metro-cities, the sewage is partially treated but these management practices are not enough.

2. Industrial effluent: Different industries and factories release effluents which may contain toxic and harmful components, such as various pigments, bleaching chemicals, leather pieces, fibres, mercury, lead, etc.

3. Oil pollution: Oil spillages are seen in the seas due to leakage of crude oil. The crude oil is hazardous as it contains cancer causing hydrocarbons.

4. Fertilizers and pesticides: These compounds when used in farm, may get washed off to nearby water body. The chemical fertilizer containing N, P, K cause water pollution. Pesticides such as endrin, chlorine, carbonate containing pesticides, etc. are mixed with water. They cause contamination of the aquatic animals.

5. The wrong behaviour of human beings causes water pollution. The addition of wastes, defecation near coasts, washing clothes, decomposing hemp and flax in water, disposal of ashes, floral offerings to god, dumping ashes all such activities result into water pollution.

6. The warm water released into the water body through thermal power plants cause thermal pollution.

Question 5.
What are the effects of water pollution on human beings?
Answer:
The water-borne diseases that are caused by different bacteria and viruses cause infections to human beings through contaminated water. Some bacterial and viral diseases are spread through epidemics. Cholera, hepatitis, enteritis, diarrhoea, typhoid are such diseases that can cause severe infections to man. Polluted water also cause skin diseases and deformities of bones, Some pollutants accumulated in vital organs cause their ailments. Liver, kidneys, brain, etc. are affected in this way. Person may develop hypertension too due to pollutants.

Question 6.
What are the effects of water pollution on the ecosystem?
Answer:
Biological effects:

1. Plants in the ecosystem show retarded growth, resulting into species loss.
2. Due to imbalance in the ecosystem, the food chain and food web is disturbed.
3. Pollutants cause mortality in fish and other aquatic animals.
4. Oil slick causes harmful impact on the marine birds.
5. Useful bacterial fauna in the water is lost.

Abiotic effects:

1. Pollutants cause changes in physical and chemical properties of water.
2. Salinity of the water changes.
3. Dissolved oxygen in the water is depleted, causing mortality of fishes.

Question 7.
Describe the effects of air pollution on the environment.
Answer:
Air pollution can cause the following serious effects on the environment:

1. Deforestation and fuel consumption bring about rise in CO₂ concentration.
2. Excess CO₂ in air causes rise in atmospheric temperature of the earth.
3. The increased temperature is called global warming.
4. The global warming results into melting of glaciers, subsequently causing rise in the sea level.
5. There is a change in the climate and pattern of rainfall. This may indirectly affect the agricultural production.

Question 8.
Describe the effects of soil pollution.
Answer:
Effect of soil pollution:

1. There are many pathogenic bacteria, viruses and parasitic intestinal worms in the sewage sludge. These are able to cause many diseases.
2. Soil and vegetable crops are contaminated by manure made from human and animal excreta containing pathogens. This can lead to various diseases.
3. There is loss of fertility and productivity of soil and land due to soil pollution.
4. Soil pollution leads to water pollution, when toxic chemicals leach into the groundwater. Similarly, when contaminated soil enters into streams or lakes, it also causes water pollution.
5. Radioactive materials and soil contaminants can travel through food chains. They move away from the soil into crops, livestock and human bodies.

Question 9.
How do biodegradable and non- biodegradable wastes cause land pollution?
Answer:

1. Biodegradable material is mainly present in the domestic waste.
2. It is in the form of food waste, peels of fruits, vegetables, etc.
3. Paper is also a main part of the domestic waste which is biodegradable.
4. Polythene bags, plastic waste and footwear, etc. are non-biodegradable waste from the domestic sources. All of these pollute the land.

Question 10.
How do you protect soil from being polluted?
Answer:

1. We should not throw domestic waste and industrial waste indiscriminately on the land, so that it contaminates soil.
2. Proper disposal of solid wastes and more importantly safe disposal of biomedical waste material should be practised.
3. Instead of throwing non-biodegradable materials on the land, they should be properly recycled and reused.
4. Biodegradable materials should be composted and converted into useful manure, rather than throwing them to cause pollution of the soil.
5. Excessive use of fertilizers and pesticides should be avoided so that the soil does not get contaminated.

Question 11.
What are the different laws to prevent pollution?
Answer:
The different laws to prevent pollution are as follows:

1. Water (Prevention and Control of Pollution) Act, 1974.
2. Air (Prevention and Control of Pollution) Act, 1981.
3. Environment (Protection) Act, 1986.
4. There are different laws and rules which have been made for the disposal of hazardous waste, biomedical waste, solid waste and prevention of noise pollution.

Question 12.
Who implements the laws related to pollution?
Answer:
The Central Pollution Control Board (CPCB) and Maharashtra Pollution Control Board (MPCB) check whether the organizations like factories, industrial estates, Municipalities, Zilla Parishads, Panchayat Samities and Gram Panchayats follow all the laws related to control of pollution.

Use your brain power!

Question 1.
Which types of pollutants are observed?
Answer:
Pollutants are of many varied types. They can be classified according to their sources, according to which ecosystem they are polluting, and according to their characteristics.

Question 2.
Whether the pollutants are degradable or non-degradable?
Answer:
Some pollutants are biodegradable while some are non-biodegradable. The pollutants that spread in the air are in the form of gases or particulate matter. Though they are non-degradable, they constantly make chemical reactions with each other.

The pollutants thrown in water and on land are of both the types. Pollutant like plastic is totally non-biodegradable. The biodegradable substances can be decomposed by various bacteria and fungand are converted back into elemental form. The pollutants added in S the water are also of two types. The heavy metals and colours are non-degradable.

Think about it:

Question 1.
If natural materials are pollutants, why do we not perceive their adverse effects during their use? When such materials are referred as pollutants?
Answer:
The natural pollutants are active only for a short duration. Due to natural reasons their activity is limited, and they are lost after a specific time. Their sources are not continuous and their spread too is not regular as in case of man-made pollutants which are emitted steadily.

Thus, we can avoid these substances. We also use them in limited quantity. Therefore, the natural substances, though may be polluting in nature, we are unable to perceive its toxicity. However, if we use them in abundance and create an imbalance, then its effect can be experienced as a great hazard.

Question 2.
What are the reasons other than those mentioned on the textbook page no. 55 mentioned responsible for air pollution?
Answer:
1. The automobile vehicles like two-wheelers and four-wheelers are increasing tremendously in numbers. This uncontrolled number of vehicles and their heavy traffic is causing air pollution to very high level in megacities.
2. Construction industries, demolition of the old buildings, digging the roads, are such activities which are adding to the particulate air pollution of the cities.
3. The bursting of firecrackers on the occasion of festivals and ceremonies, the spread of gulal during processions are also actions which result into unwanted air pollution.
4. Aeroplane traffic, rocket launching, industrial farming are the modern sources of air pollution.

Question 3.
Whether the vehicles with two- stroke engine cause more pollution than four stroke engine?
Answer:
Yes, they do. Scooters and motor cycles are more dominant source of air pollution as they emit soot and organic particles. In urban areas this proportion is high. These particles are toxic and they create heavy air pollution.

The two-wheelers have two-stroke engines. Such engines are far less efficient in burning the fuel that is used in the vehicles. The exhaust systems are also less effective at removing pollutants. On the contrary most of the four-wheelers have catalytic converters. Therefore, the exhaust fumes from scooters contain higher levels of the chemicals found in the fuel and oil they use.

The vehicles with two-stroke engine such as two wheelers emit significantly more primary organic aerosols and volatile organic compounds from incomplete burning of the fuel. They also produce significant secondary organic aerosols as gases released from the exhaust react with the air and microscopic particles of soot.

These pollutants increase the risk of heart and lung disease. Older two-stroke vehicles produced reactive oxygen molecules that are known to be potentially harmful for lung health. In recent times there is excessive use of two-wheelers which is deteriorating the air quality to great extent.

Question 4.
Give 5 examples of each of domestic waste, biological waste and agricultural waste and write in your own words about soil pollution due to those wastes.
Answer:
Domestic waste:

1. Empty containers of medicines, papers, bottles, etc.
2. Plastic
3. Glass pieces
4. Old utensils, clothes
5. Tins and cartons of used items, the discarded household items.

Biological waste:

1. Dead corpse of animals.
2. Urine and faeces
3. Peels of fruits, stalks of vegetables and fruits.
4. Food waste
5. Garlands and old bouquets.

Agricultural waste:

1. The stubs of crops after the grains are removed.
2. Cattle dung and urine
3. Some persistent amount of insecticides
4. Some amount of fertilizers
5. Empty containers, bags, cartons of insecticide, chemical fertilizers, seeds, gunny bags, etc.

Diagram based questions:

Question 1.
Given below is a diagram showing hazardous polluting event.
Explain what is this and what are its effects shown in the diagram.

Answer:
The above picture depicts the formation and effects of acid rain. The toxic gases such as SO2 , CO2 and NO2 are released through the chimneys of factories. These oxides are released in air. They get dissolved in the rainwater and reach back the earth’s surface in the form of acids. The plants, animals and houses are being damaged due to this acid rain.

Question 2.
Draw a well labelled diagram to show greenhouse effect.
Answer:

Activity based questions:

Question 1.
Discuss the issues like ‘dry waste-wet waste’ and ‘toilet in each home’ and write information in your own words.

MCQs based on practical:

Question 1.
Which fertilizers when used in excessive amounts cause soil pollution that spreads to neighbouring water bodies and cause water pollution too?
(a) Chemical
(b) Organic
(c) Artificial
(d) Compost
Answer:
(a) Chemical

Question 2.
What is the type of pollutants that are present in the industrial effluents that is released in the rivers and sea?
(a) Inorganic
(b) Organic
(c) Biological
(d) Biomedical
Answer:
(a) Inorganic

Question 3.
What grows in excess when eutrophication of the water bodies take place?
(a) Plants
(b) Algae
(c) Fishes
(d) Fungi
Answer:
(b) Algae

Question 4.
Which of the following is seen in the polluted water body?
(1) flowers used in pooja
(2) fruits
(3) fishes
(4) aquatic insects
(5) plastic bags
(6) turtles
(7) thick growth of algae
(8) light blue colour of water
(9) cattle wading in water
(10) broken idols
(a) (1) (3) (5) (6) (9) (10)
(b) (1) (2) (5) (7) (9) (10)
(c) (1) (3) (6) (8) (9) (10)
(d) (1) (2) (4) (7) (8) (9)
Answer:
(b) (1) (2) (5) (7) (9) (10)

Question 5.
Which is the easiest method to identify the polluted water?
(a) To taste the water
(b) To check the depth of water
(c) To observe colour and odour of the water
(d) To swim in the water
Answer:
(c) To observe colour and odour of the water

Formative Evaluation:

Question 1.
Which factors are responsible for pollution shown in the following pictures?

Question 2.
Compare the two neighbouring photographs.

Balbharati Maharashtra State Board 8th Std Science Textbook Solutions 

• Living World and Classification of Microbes Class 8 Science Textbook Solutions
• Health and Diseases Class 8 Science Textbook Solutions
• Force and Pressure Class 8 Science Textbook Solutions
• Current Electricity and Magnetism Class 8 Science Textbook Solutions
• Inside the Atom Class 8 Science Textbook Solutions
• Composition of Matter Class 8 Science Textbook Solutions
• Metals and Nonmetals Class 8 Science Textbook Solutions
• Pollution Class 8 Science Textbook Solutions
• Disaster Management Class 8 Science Textbook Solutions
• Cell and Cell Organelles Class 8 Science Textbook Solutions

Std 6 Science Chapter 16 The Universe Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 6 Science Solutions Chapter 16 The Universe Notes, Textbook Exercise Important Questions and Answers.

Class 6 Science Chapter 16 The Universe Question Answer Maharashtra Board

1. Name these.

Question a.
Birthplace of stars.
Answer:
Nebulae

Question b.
The biggest planet in the Solar System.
Answer:
Jupiter

Question c.
The galaxy which is our neighbour.
Answer:
Andromeda

Question d.
The brightest planet in the solar system.
Answer:
Venus

Question e.
Planet with the largest number of satellites.
Answer:
Jupiter

Question f.
Planet without a single satellite.
Answer:
Venus and Mercury

Question g.
Planet with a rotation different from other planets.
Answer:
Venus

Question h.
A celestial body that carries a tail along.
Answer:
Comet

2. Fill in the blanks.

Question a.
The group of galaxies of which our Milky Way is a part is called ………….. .
Answer:
Local group

Question b.
Comets are made of ………… .
Answer:
ice and dust particles

Question c.
The planet ……………… appears as if it is rolling along its orbit.
Answer:
Uranus

Question d.
…………….. is a stormy planet.
Answer:
Jupiter

Question e.
The pole star is the best example of a ………………. type of star.
Answer:
variable

3. Say if the statements given below are right or wrong. Rewrite the statements after correcting them.

Question a.
Venus is the planet closest to the sun.
Answer:
Wrong: Mercury is the planet closest to the sun.

Question b.
Mercury is called a stormy planet.
Answer:
Wrong: Jupiter is called a stormy planet.

Question c.
Jupiter is the biggest planet.
Answer:
Right

4. Answer the following.

Question a.
What is a special characteristic of the planet Mars?
Answer:
The highest and the longest mountain in the solar system ‘Olympus Mons’ is located on Mars.

Question b.
What are the type of galaxies?
Answer:
The different types of galaxies identified according to their shapes are spiral, elliptical, barred spiral, irregular.

Question c.
Which celestial bodies does a galaxy include?
Answer:
Galaxy includes stars, their planetary system, cluster of stars, nebulae, clouds of gases, clouds of dust, dead stars, newly bom stars etc.

Question d.
Name the different types of stars.
Answer:
The different types of stars are

1. Sun-like stars e.g. stars like Sirius, Alpha Centauri
2. Red Giants Stars
3. Super Nova
4. Binary or Twin Stars
5. Variable Stars e.g. Polaris (pole star)

Question e.
What are the types of comets and on what basis are they classified?
Answer:

1.  Comets are of two types: Long-period comets and short-period comets.
2. Classification of comets is based on the time (period) taken by the comets to complete one revolution around the sun.

Question f.
What is the difference between meteors and meteorites?
Answer:

1. Meteors are rocky pieces originating from the asteroid belt. Smaller rocky pieces get completely burnt due to friction with air after they enter the earth’s atmosphere.
2. Meteors which do not bum completely and fall to the surface of the earth are called meteorites.

Question g.
What are the characteristics of the planet Neptune?
Answer:
Neptune is the eighth planet in the solar system. A season on Neptune lasts for about 41 years. On this planet winds blow with extremely high speed.

5. Match the following.

Question a.

Answer:

Activity:

Question 1.
Using the material you can find in your house, prepare a model of the solar system.

Question 2.
Collect information about different aspects of each planet such as its distance from the sun, its diameter, its volume, etc. and present it in a science exhibition.

Class 6 Science Chapter 16 The Universe Important Questions and Answers

Fill in the blanks.

Question 1.
The Milky Way is known as ………….. .
Answer:
Mandakini

Question 2.
The ………….. is a galaxy in which our solar system is located.
Answer:
Milky Way

Question 3.
The galaxy that is closest to our Milky Way is ………….. .
Answer:
Andromeda

Question 4.
The universe includes innumerable galaxies, the space between them and also ………….. .
Answer:
energy

Question 5.
The Milky Way is a part of the ………….. of galaxies.
Answer:
Local group

Question 6.
Generally, the surface temperature of stars ranges from 3500° C to ………….. .
Answer:
50000°C

Question 7.
The colour of stars changes according to their ………….. .
Answer:
temperature

Question 8.
Red giants stars are ………….. in colour.
Answer:
red

Question 9.
Super Nova stars are ………….. and ………….. than the red giant stars.
Answer:
brighter, larger

Question 10.
More than ………….. of the stars in the sky are ………….. stars.
Answer:
half, binary

Question 11.
The ………….. and ………….. of variable stars is not stable.
Answer:
luminance, shape

Question 12.
When a star contracts, its surface temperature ………….. and the star emits ………….. energy and appears ………….. .
Answer:
increases, greater, brighter

Question 13.
The sun which is at the centre of the solar system is a ………….. coloured star.
Answer:
yellow

Question 14.
The diameter of the sun is approximately ………….. km.
Answer:
13, 92, 000

Question 15.
………….. is the fastest moving planet.
Answer:
Mercury

Question 16.
………….. is the brightest planet in the solar system.
Answer:
Venus

Question 17.
………….. is the hottest planet.
Answer:
Venus

Question 18.
As the earth is a ………….. there is a magnetic field around the earth.
Answer:
magnet

Question 19.
Mars is also called the ………….. .
Answer:
Red planet

Question 20.
As the soil on Mars contains ………….. its colour is reddish.
Answer:
iron

Question 21.
………….. planets of the size of the earth can get accommodated on Jupiter.
Answer:
1397

Question 22.
Jupiter is called as ………….. .
Answer:
The stormy planet

Question 23.
Saturn mass is ………….. times that of the earth.
Answer:
95

Question 24.
………….. cannot be seen without a telescope.
Answer:
Uranus

Question 25.
Winds blow with extremely high speed on ………….. .
Answer:
Neptune

Question 26.
………….. is the satellite of the earth.
Answer:
The moon

Question 27.
The moon’s period of ………….. and ………….. are both of 27.3 days.
Answer:
rotation, revolution

Question 28.
………….. is classified as a dwarf planet.
Answer:
Pluto

Question 29.
Pluto takes ………….. years to complete its revolution around the sun.
Answer:
248

Question 30.
………….. are formed out of ice and dust particles.
Answer:
Comets

Question 31.
………….. lake in Maharashtra has been formed by the impact of such a meteorite.
Answer:
Lonar

Can you tell?

Question 1.
Which celestial bodies form the solar system?
Answer:
Sun, the eight planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, their satellites, Dwarf planets, asteroids, meteors and comets all together form our solar system.

Question 2.
What is the difference between stars and planets?
Answer:

Question 3.
How many planets are there in our solar system?
Answer:
There are 8 planets in our solar system.

Question 4.
What is to be found between Mars and Jupiter?
Answer:
A belt of celestial bodies called as asteriods is found between the planets Mars and Jupiter.

Question 5.
Have you ever seen in the evening or in the pre-dawn hours a large celestial body with a long tail? What is it called?
Answer:
Yes, it is a comet – a large celestial body with a long tail. I have not seen it, but heard that in 1986 there was a Halley’s comet seen in the Indian sky.

Use your brain power!

Question 1.
Why do we see only one side of the moon?
Answer:
As the moon revolves around the earth it also rotates around itself. The moon takes 27.3 days to complete one revolution around the earth. It takes the moon the same time to complete one rotation around itself. Therefore, only one side of moon is visible.

Question 2.
Which planet has a day longer than its year?
Answer:
A planet’s day is how long it takes to complete one rotation on its own axis. Venus takes 243 earth days to complete one rotation because of its slow rotation around its axis. A year is the time taken by the planet to complete one revolution around the sun. Venus completes one revolution around the sun in 225 days. This makes a day longer than a year on Venus.

Answer in one sentence.

Question 1.
What is the Milky Way?
Answer:
Milky way is the galaxy in which our solar system is located.

Question 2.
What is a galaxy?
Answer:
A group of innumerable stars and their planetary systems are together known as galaxy.

Question 3.
What does the Universe include?
Answer:
The universe includes innumerable galaxies, the space between them and also energy.

Question 4.
What different colours do the stars radiate?
Answer:
The stars radiate different colours such as blue, white, yellow and red.

Question 5.
Where are stars bom?
Answer:
The birth place of stars are the huge nebulae, made of dust particles and gases.

Question 6.
What is the surface temperature of the sun?
Answer:
The surface temperature of the Sim is around 6,000°C.

Question 7.
What is the size of the sun?
Answer:
The size of the sun is so huge that around 13 lakh planets of the size of the earth can be easily placed within it.

Question 8.
How does the sun balance the other celestial bodies?
Answer:
Due to the gravitational force of the sun, the celestial bodies in the solar system revolve around it.

Question 9.
How does the sun move in the Milky Way?
Answer:
The sun rotates around its axis and while doing so, it revolves around the centre of the Milky Way taking the solar system along with it.

Question 10.
Which planet doesn’t have atmosphere?
Answer:
Mercury doesn’t have atmosphere.

Question 11.
How much time does the earth take to complete one rotation and one revolution?
Answer:
The earth completes one rotation in 24 hrs and one revolution in 365 days i.e. 1 year.

Question 12.
Which planets have rings around them?
Answer:
Jupiter, Saturn, Uranus, Neptune have rings around them.

Question 13.
Which planet do not have rings around them?
Answer:
Mercury, Venus, Earth and Mars do not have rings around them.

Question 14.
State two properties of planet Mercury.
Answer:
Mercury is the closet planet to the Sim. Mercury is the fastest moving planet.

Question 15.
When is the Mercury visible to us?
Answer:
Mercury is visible in the morning and in the evening if it is away from the sun.

Question 16.
What is seen on the surface of the mercury?
Answer:
A number of depressions which are actually caused by meteoric falls are seen on the surface of mercury.

Question 17.
When is Venus seen in the sky?
Answer:
Venus is seen in the sky in the east before the sunrise and in the west after the sunset. It rotates around itself from east to west.

Question 18.
How does earth protect us from harmful rays of Sun?
Answer:
As the earth is a magnet there is a magnetic field around the earth. It diverts the harmful rays from the sun towards the polar regions of the earth.

Question 19.
What is Olympus Mons?
Answer:
Olympus Mons is the highest and longest mountain in the solar system located on Mars.

Question 20.
Which is the largest planet of the solar system?
Answer:
The Jupiter is the largest planet of the solar system.

Question 21.
Why is Saturn considered a peculiar planet?
Answer:
Saturn considered a peculiar planet because of the rings around it.

Question 22.
How is the axis of Uranus?
Answer:
Uranus axis is so greatly inclined that it appears as if it is rolling along on its axis.

Question 23.
How are seasons on Neptune?
Answer:
The seasons on Neptune last for about 41 years.

Question 24.
What is a satellite?
Answer:
The celestial bodies that revolve around a planet , without independently revolving around the sun are called Satellite.

Question 25.
What is an Asteroid?
Answer:
A great number of small sized bodies could not turn into planets when the solar system was formed, but continued to revolve around the sun. This bodies are known as asteroids.

Question 26.
What is a Dwarf Planet?
Answer:
A small sized celestial body that revolves independently around the sun is called the dwarf planet.

Question 27.
What is a comet?
Answer:
A comet is a celestial body that revolves around sun. Comets are formed out of ice and dust particles.

Question 28.
What are meteors?
Answer:
Meteors are rocky pieces originating from the asteroids belt.

Question 29.
What are meteorites?
Answer:
Meteors which do not bum completely and fall to the surface of the earth are called meteorites.

Give reasons for the following.

Question 1.
Comets came to be called ‘dirty snowballs’.
Answer:
Comets consist of an icy cluster of various constituents like dust particles. Hence it is called dirty snowballs.

Question 2.
Comets are visible when they are close.
Answer:
Comets are formed out of ice and dust particles. They appear like points when they are far away from the sun, but when they are close to the sun they become easily visible to us because of the shorter distance and the heat of the sun.

Question 3.
Comets appear to have a long feathery tail.
Answer:
Comets are made up of frozen matter and dust particles. When they are close to the sun this frozen matter gets converted into gas due to the solar heat. These gases get thrown in a direction away from the sun. As a result comets appear to have a long feathery tail.

Question 4.
Pluto is called as a dwarf planet.
Answer:
Pluto is a small sized celestial body that revolves independently around the sun.

Question 5.
Moon is a satellite of the earth.
Answer:
Moon revolves around the earth without independently revolving around the sun. Hence moon is a satellite of the earth.

Question 6.
Mars is called the Red Planet.
Answer:
As the soil on the Mars contains iron its colour is reddish. Hence Mars is also called the RedPlanet.

Question 7.
Jupiter is called the Stormy Planet.
Answer:
Jupiter revolves around itself with a great speed. Hence Jupiter is called the Stormy planet.

Question 8.
Uranus appears rolling along on its orbit.
Answer:
Uranus axis is so greatly inclined that it , appears as if it is rolling along on its orbit.

Question 9.
Saturn is considered to be a peculiar planet.
Answer:

1. Saturn is considered as peculiar planet because of its rings around it.
2. Though its mass is 95 times that of the earth, its density is very low.
3. If it were dropped into a large sea enough to hold it, it would float in it.

Maharashtra State Board Class 6 Science Textbook Solutions

• Work and Energy Class 6 Science Textbook Solutions
• Simple Machines Class 6 Science Textbook Solutions
• Sound Class 6 Science Textbook Solutions
• Light and the Formation of Shadows Class 6 Science Textbook Solutions
• Fun with Magnets Class 6 Science Textbook Solutions
• The Universe Class 6 Science Textbook Solutions

Std 8 Science Chapter 17 Man-made Materials Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 17 Man-made Materials Notes, Textbook Exercise Important Questions and Answers.

Class 8 Science Chapter 17 Man-made Materials Question Answer Maharashtra Board

Class 8 Science Chapter 17 Man-made Materials Textbook Questions and Answers

1. Try to find it:

Question a.
Plastic shows …………. property, hence it can be moulded to any shape.
Answer:
Plastic shows plasticity property, hence it can be moulded to any shape.

Question b.
Motor cars are coated with ……… .
Answer:
Motor cars are coated with Teflon.

Question c.
Thermocol melts at ………… °C.
Answer:
Thermocol melts at more than 100 °C (it is about 240 °C).

Question d.
…………….. glass dissolves in water.
Answer:
Alkali silicate or water glass dissolves in water.

2. Who is my partner?

Question a.

Answer:

3. Answer the following.

Question a.
Thermocol is produced from which material?
Answer:
Thermocol is made from polystyrene which is also a complex thermoplastic substance.

Question b.
Write uses of PVC.
Answer:
PVC or Polyvinyl chloride is used for making bottles, raincoat, pipes, handbags, shoes, electric cable insulation, furniture, ropes, toys, etc.

Question c.
Write the natural or man-made raw material of the following items.
Mattress, beaker, bangle, chair, gunny bag, broom, knife, pen.
Answer:

Question d.
Which are the main ingredients of glass?
Answer:
The main ingredients of glass are sand and silica.

Question e.
How the plastic is produced?
Answer:

1. Plastics are derived from natural materials such as natural gas, oil, coal, minerals and plants.
2. The first synthetic plastics were i derived from cellulose, a substance found in plants and trees. This cellulose was heated with chemicals and resulted in a plastic like material.
3. In modern times, the different raw materials are used for making plastics, but most plastics are made from the hydrocarbons present in the natural gas, oil and coal.
4. Plastics are simply chains of like molecules linked together. These chains are called polymers. Thus, many plastics begin with “poly,” such as polyethylene, polystyrene and polypropylene.
5. These polymers are made of carbon and hydrogen and sometimes oxygen, nitrogen, sulphur, chlorine, fluorine, phosphorous or silicon.
6. Plastic is produced in factories by suitable chemical reactions.

4. Distinguish between. 

Question a.
Man-made material and natural material
Answer:

Question b.
Thermoplastic and Thermosetting plastic:
Answer:

5. Answer the following in your own words.

Question a.
Explain the effect of following materials on environment and human health.
1. Plastic
2. Glass.
3. Thermocol.
Answer:
1. Plastic:

1. Plastic is non-degradable substance. Hence if thrown in any ecosystem, it remains unchanged for many years.
2. It is one of the worst environmental pollutants as its disposal is a major problem.
3. If thrown in water bodies, it affects the aquatic animals. Many of turtles mistake it for algae and eat the plastic. Eventually such animals die due to choking.
4. In terrestrial environment, the grazing animals like cattle are affected due to plastic.
5. If burnt it emits very toxic gases.
6. In landfill sites, it remains unchanged for thousands of years.

2. Glass:

1. The glass production is carried out at high temperatures of about 1500 °C. This burning emits many hazardous gases like sulphur dioxide, nitrogen dioxide, carbon dioxide. These gases cause the greenhouse effect.
2. Moreover, glass being non-degradable, cause pollution.
3. If broken glass pieces or any waste glass material is disposed into aquatic environment, it affects animals and plants.
4. Similarly, glass pieces block the drainages.
5. The waste glass thrown anywhere cause injury to terrestrial fauna.

3. Thermocol:

1. Thermocol contains carcinogenic ingredients in the form of styrene. If there is prolonged contact with thermocol, there is a possibility of blood cancer like leukemia and lymphoma.
2. Thermocol is non-degradable. It cannot be degraded into harmless substances easily.
3. If it is burnt for destruction, it releases toxic gases in atmosphere.
4. The plates and cups used for food, water, tea, etc. are made up of thermocol. This may affect the health. Reheating the food kept in thermocol releases styrene. This styrene may dissolve in that food, causing health problems like cancer.

Question b.
Which measures will you arrange to minimize the environmental problems arising due to non-degradable plastic?
Answer:

1. The use of plastic should be minimum. Reducing the consumption, reusing the same plastic again and again, recycling the used plastic and making some new products from the used plastic are some of the measures that can be adopted.
2. There are attempts to use plastic in making roads. Therefore, plastic is bought with good price at some places.
3. Therefore, instead of disposing of it anywhere, it should be collected and sold in best possible way.
4. The better alternatives for plastic should be adopted.
5. The awareness programmes about misuse of plastic should be arranged so that common man can understand the dangers of using plastic.

6. Write short notes. 

Question a.
Glass production:
Answer:
The general preparation of the glass is as follows:

1. Mixture of sand, soda, lime and small quantity of magnesium oxide is heated in furnace.
2. At 1700 °C sand or silicon dioxide melts.
3. To make the mixture melt at lesser temperature, pieces of discarded glasses are added to it.
4. This addition makes the mixture to melt at lesser temperature of 850 °C.
5. When all the ingredients of mixture are liquified, then again it is heated up to 1500 °C.
6. This heating is immediately followed by cooling.
7. The sudden cooling causes the mixture to become homogeneous, amorphous and transparent instead of crystalline.
8. For variety of glass types, different proportions of ingredients are used for heating.

Question b.
Optic glass:
Answer:

1. Optic glass or optical glass needs to be very clear and transparent as it is used in spectacles, lenses and other devices like microscopes.
2. Optic glasses are produced from the mixture of sand, soda, limestone, barium oxide and boron.

Question c.
Uses of plastic:
Answer:
Plastic, the man-made material is used in various forms in modern age. According to the type of plastic, its uses are different.

I. Thermoplastic materials are used for manufacturing following articles:

1. Polyvinyl chloride or PVC is used to make bottles, raincoat, pipes, handbags,: shoes, electric cable insulation, furniture, ropes, toys, etc.
2. Polystyrene is used in making thermo insulating parts of electric appliances like refrigerators, gears of machines, toys, protective coverings like covers of CD and DVD, etc.
3. Polyethylene (PE) plastics are used for making milk bags, packing bags, flexible garden pipes, etc.
4. Polypropylene (PP) is used in making parts of loudspeakers and vehicles, ropes, mattresses, laboratory appliances, etc.

II. Thermosetting plastic is used in the manufacturing of the following items:

1. Bakelite for making cabinets of radio, T.V., telephones, electric switches, toys, plastic handles of cookers, etc.
2. Melamine for making domestically useful items like cup – saucers, plates, tray, some spare parts of airplane engines, electric and sound insulating coverings, etc.
3. Polyurethane in making surfing boards, small boats, furniture, seats in vehicles, etc.
4. Polyester in fibreglass, toners of laser printers, textile industry, etc.

Can you tell?

Question 1.
Make a list of 20 different man-made materials present in your home, school and places around and discuss.
Answer:
Schoolbag, books, computer, table lamp, tube lights, benches, shoes, dress, pencil, pen, tiffin box, water bottle, raincoat, umbrella, medicine tablets, pen drive, chalk, duster, utensils, gas burner, biscuits.

Can you recall?

Question 1.
How many plastic carry bags are brought in your home in a day? What happens to those later on?
Answer:
Till May 2018 about one or two plastic bags were brought in our home every day. But now due to prohibition on plastic bags and other plastic items by the Government, the use of plastic has been drastically reduced. The bags brought at home caused lot of plastic pollution. Plastic is non-biodegradable, thus it always created problem of their disposal.

If dumped in a water body, it can be hazardous for aquatic animals. If thrown in the garbage, plastic articles find their way to landfilling areas. If thrown anyhow plastic may be consumed by stray animals. This causes toxic effects on them. If burnt they emit toxic gases.

Question 2.
How are the used up and thrown away carry bags, water bottles, milk bags recycled?
Answer:
The plastic waste is collected by the kabadiwala or sweepers. They sell these articles to the recycling units. In recycling units, the recycling of some of the plastic items is done. This leads to formation of plastic of low quality which may be used in making some newer plastic items.

Question 3.
Which material is wrapped around the items of glass or similar material during transport to prevent from breaking up?
Answer:
The plastic bubble wrap or thermocol is used to protect fragile items from the shocks and breaks during their transport.

Project:

Question 1.
Collect the information about the plastic used in production of utensils used in microwave oven.

Question 2.
Collect the information about the material used in production of denture. (A set of artificial teeth)

Class 8 Science Chapter 17 Man-made Materials Important Questions and Answers

Try to find it:

Question 1.
The plastic that can be moulded as per our wish is called …………… .
Answer:
The plastic that can be moulded as per our wish is called thermoplastic.

Question 2.
…………… is a type of plastic used for manufacturing artificial teeth.
Answer:
Polyacrylic is a type of plastic used for manufacturing artificial teeth.

Question 3.
Thermocol is a form of a complex material called ……………. .
Answer:
Thermocol is a form of a complex material called polystyrene.

Write whether the following statements are True or False: Rewrite the false statements after correcting:

Question 1.
Plastics are inorganic polymers that show plasticity.
Answer:
False. (Plastics are organic polymers that show plasticity.)

Question 2.
Polythene, PVC are thermosetting plastic materials.
Answer:
False. (Polythene, PVC are thermoplastic materials.)

Question 3.
Plastic is bad conductor of heat and electricity.
Answer:
True.

Question 4.
Surfing boards are made up of bakelite.
Answer:
False. (Surfing boards are made up of polyurethane.)

Question 5.
Being bad conductor of electricity, glass is used as insulator in electric appliances.
Answer:
True.

Match the columns:

Question 1.

Answer:

Find the odd one out:

Question 1.
Bakelite, Melamine, Polystyrene, Polyester.
Answer:
Polystyrene (All others are thermosetting plastic materials, polystyrene is thermoplastic.)

Question 2.
Polyvinyl chloride, Polystyrene, Polypropylene, Polyurethane.
Answer:
Polyurethane (All others are thermoplastic materials, polyurethane is thermosetting plastic.)

Question 3.
Vegetable peels, Cotton bolls, Wooden scraps, Plastic bag.
Answer:
Plastic bag (All others are degradable materials, plastic is non-degradable.)

Question 4.
Teflon, Polyacrylic, Fibreglass, Polyester.
Answer:
Fibreglass (All others are types of plastic.)

Considering the relationship in the first pair, complete the second pair:

Question 1.
Processed glass: Fen glass : : Alkali silicate glass : ………..
Answer:
Water glass

Question 2.
Ferrous oxide: Bluish green glass : : Copper oxide : ……..
Answer:
Red glass

Question 3.
Lens : Optical glass : : Laboratory glassware : ……….
Answer:
Silica glass

Question 4.
Light bulbs, Tubes: Lead glass : : Medicine storing : ………
Answer:
Borosilicate glass

Question 5.
Glass: Mixture of silica and silicate : : Thermocol : ………..
Answer:
Polystyrene.

Distinguish between:

Question 1.
Degradable and Non-degradable substances:
Answer:

Write short notes:

Question 1.
Properties of plastic:
Answer:

1. Plastic is non-corrosive.
2. It is non-degradable as it does not decompose.
3. The factors such as humidity, heat, rain, etc. do not affect plastic.
4. Any coloured item can be manufactured from plastic.
5. Plastic shows property of plasticity. Thus it can be moulded into any shape that is needed.
6. Plastic is a bad conductor of heat and electricity.
7. Plastic is light-weight and thus preferred for carrying.

Question 2.
Properties of Glass:
Answer:
The glass becomes soft on heating and thus can be moulded into desired shape.

1. According to ingredients added at the time of preparation of glass, its density changes accordingly.
2. Glass is slow conductor of heat. If a cold glass is quickly heated, it cracks suddenly. Similarly, the warm glass if exposed to sudden cooling, it too cracks.
3. Glass is a bad conductor of electricity. Therefore, it is used as insulating material in electric appliances.
4. Glass is transparent, allowing most of light to pass through it. If there are chromium, vanadium or iron oxides in the glass, large amount of light is absorbed in glass.

Answer the following questions in one sentence only:

Question 1.
What is the use of plastic in healthcare sector?
Answer:
Saline bottles, pouches, blood bags, syringes and medicine bottles are made up of plastic, making plastic irreplaceable in the healthcare sector.

Question 2.
Which material is used in coating of vehicles? Why?
Answer:
Teflon is used for coating the vehicle as it protects the vehicles from scratches.

Question 3.
What is the use of polyacrylic type of plastic?
Answer:
Polyacrylic plastic used for manufacturing lenses and in the manufacture of artificial teeth.

Question 4.
What is 4R principle?
Answer:
The 4R principle is the way of behaviour that prevents or lessens the environmental pollution. The 4Rs are Reduce, Reuse, Recycle and Recover.

Question 5.
What are the eco-friendly options for a plastic bag?
Answer:
Jute bag, cloth bag and reusable bags of any natural materials are the eco-friendly options for the plastic bag.

Question 6.
How is Borosilicate glass produced?
Answer:
Borosilicate glass is produced by melting the mixture of sand, soda, boric acid and aluminium oxide.

Question 7.
When is large amount of light absorbed in the glass?
Answer:
If there are oxides of either chromium, vanadium or iron in the glass, large amount of light is absorbed in it.

Give scientific reasons:

Question 1.
It is harmful to eat food kept in thermocol.
Answer:
Thermocol is made up from polystyrene. It is carcinogenic (cancer causing) substance. When food kept in r thermocol containers is reheated, this , styrene dissolves in it. This may affect the r health of the person who consumes such food. It has been noted that there is a great possibility of blood cancer like leukaemia r and lymphoma if one remains in contact with thermocol for a longer time. Thus, it is harmful to eat food kept in thermocol.

Question 2.
Vessels used to cook food in the microwave oven are made up of plastic.
Answer:
The vessels made from metals cannot be used in the microwave oven. The microwaves cannot penetrate steel and so ‘ can only heat the contents through the open top. Some metals cause sparking with microwaves. Microwave energy is absorbed differently by different materials. Plastics of only certain kind are more suitable to be used in the microwave oven.

Answer the following:

Question 1.
What are the qualities of thermocol?
Answer:

1. Thermocol is modern man-made material made from polystyrene.
2. It can be transformed into liquid state when heated at more than 100 °C temperature. On cooling, it returns to the solid state.
3. Therefore, any desired shape can be given to it.
4. It acts as a good shock-absorber and hence used as a packing material to transport brittle material.
5. It is a bad insulator of heat and hence used for storing fish and other perishable articles in market.

Think about it:

Question 1.
Why are the plastic tanks used for storage of chemicals?
Answer:
Plastic is non-corrosive. It is comparatively non-reactive and it does not decompose. Moreover, the plastic containers are easier for handling. They are lighter and unbreakable. Hence the plastic tanks are used for storage of chemicals.

Question 2.
Why most of domestically useful items are replaced by plastic?
Answer:
Plastic is lighter and unbreakable. The handling thus becomes easier. It is non-corrosive, hence pickles, spices, etc. can be stored in plastic containers. It is cheaper as compared to the metal and glass articles. Thus, it becomes popular with general public. It is easier to wash and maintain the plastic articles. These are some of the reasons of making plastic a domestically useful material.

Collect information:

Question 1.
To prevent the degradation due to sunlight, some materials are stored in which type of bottles?
Answer:

The amber glass or brown coloured glass bottles are used to store the materials that may get degraded due to sunlight. This colour prevents the ultraviolet rays of the sun to enter the bottle and bring about chemical changes in the materials. Especially, for sensitive medicines, brown glass bottles are used.

Question 2.
Which type of glass is used in vehicles to avoid injuries in accidents?
Answer:
Front and rear doors have tempered glass. The windshield has laminated safety glass. Even if the accident takes place the glass pieces do not injure the passengers. Laminated safety glass combines two curved glass sheets and a plastic lamina between the two layers of the glass.

This glass is tough and protective. Tempered glass on the other hand is toughened glass which is processed by controlled thermal or chemical treatments. Upon breaking, the tempered glasses crumble into small granular chunks instead of splintering into sharp glass pieces. This prevents the injuries.

Sketch and label the diagram of glass manufacturing process:

Open-Ended Questions:

Question 1.
Classify and make a chart of the materials used in various items in house. Make additions to that chart with reference to various materials.

Answer:

Question 2.
Make list about use of thermocol in your daily life.
Answer:

1. Decorative items used at the time of festivals.
2. Packing materials.
3. Insulating boxes to keep food warm.
4. Insulating boxes to keep fish in iced condition to prevent decomposition.
5. Thermocol beads in the bean bags.

Balbharati Maharashtra State Board 8th Std Science Textbook Solutions

• Human Body and Organ System Class 8 Science Textbook Solutions
• Introduction to Acid and Base Class 8 Science Textbook Solutions
• Chemical Change and Chemical Bond Class 8 Science Textbook Solutions
• Measurement and Effects of Heat Class 8 Science Textbook Solutions
• Sound Class 8 Science Textbook Solutions
• Reflection of Light Class 8 Science Textbook Solutions
• Man-made Materials Class 8 Science Textbook Solutions
• Ecosystems Class 8 Science Textbook Solutions
• Life Cycle of Stars Class 8 Science Textbook Solutions

Std 8 Science Chapter 1 Living World and Classification of Microbes Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 1 Living World and Classification of Microbes Notes, Textbook Exercise Important Questions and Answers.

Class 8 Science Chapter 1 Living World and Classification of Microbes Question Answer Maharashtra Board

Class 8 Science Chapter 1 Living World and Classification of Microbes Textbook Questions and Answers

1. Use Whittaker method to classify bacteria, protozoa, fungi, algae, prokaryotic, eukaryotic, microbes.

Living World And Classification Of Microbes Exercises  Question 1.
Use Whittaker method to classify bacteria, protozoa, fungi, algae, prokaryotic, eukaryotic, microbes.
Answer:

• Bacteria: Kingdom Monera
• Protozoa: Kingdom Protista
• Fungi: Kingdom Fungi
• Algae: If unicellular, Kingdom Protista. If multicellular, Kingdom Plantae
• Prokaryotic: Kingdom Monera
• Eukaryotic: Any kingdom other than Monera.
• Microbes: Kingdom Monera or Protista.

2.  Complete the five kingdom method of classification using-living organism, prokaryotes, eukaryotes, multicellular, unicellular, protista, animals, plants, fungi.

Living World And Classification Of MicrobesQuestion 1.
Complete the five kingdom method of classification using-living organism, prokaryotes, eukaryotes, multicellular, unicellular, protista, animals, plants, fungi.

Answer:

3. Find out my partner 

Question 1.

Answer:

4. State whether the following statements are True or False. Explain your statement:

Question a.
Lactobacilli are harmful bacteria.
Answer:
False.
Explanation Lactobacilli are useful bacteria. They are used for curdling the milk. They are also used for preparing variety of milk products.

Question b.
Cell wall of fungi is made up of chitin.
Answer:
True.
Explanation The cell wall of the plants is made up of cellulose while the cell wall of fungi is made up of complex sugar called chitin. Inside the fungal cell wall there is cytoplasm which contains many nuclei.

Question d.
Organ of locomotion in amoeba is pseudopodia.
Answer:
True.
Explanation Amoeba is a protozoan, primitive organism which possesses pseudopodia as the organ for locomotion.

Question e.
Tomato wilt is a viral disease.
Answer:
True.
Explanation: Tomato wilt is a viral disease. These viruses are able to infect only plant cells.

5. Give answers

Question a.
State the merits of Whittaker’s method of classification.
Answer:
For the answer of Merits of Whittaker’s method refer to point I of answer given on this Digest’s page no. 11; under “Use your brain power!”

Question b.
Write the characteristics of viruses.
Answer:
1. Viruses are extremely minute of the size range of 10 nrn to 100 nm. They are on the borderline of living and non-living. They are 10 to 100 times smaller than bacteria and are visible only through the electron microscope.

2. Though they are not considered as living, they can make replica of their own.
3. They exist in the form of independent particles. They are long molecules of DNA or RNA which are covered by a protein coat.

4. Their survival is possible only inside the living plant or animal cells. When they infect the host cells, they produce their own proteins with the machinery of the host cell. These proteins form many replicas of the infecting virus.

5. This infection destroys the host cell and the virus replicas are released. These free replicas re-infect the other adjoining cells of the host.
6. Most of the viruses are pathogenic, they cause diseases in plants and animals.

Question c.
Explain the nutrition in fungi.
Answer:
Most of the fungi are saprophytic in their nutrition. They absorb the nourishment from dead and decaying matter. By taking the organic matter from dead bodies of plants and animals, fungi survive. In this process they degrade the organic matter completely.

Question d.
Which living organisms are included in the kingdom Monera?
Answer:

1. All the living organisms belonging to Kingdom Monera are unicellular.
2. The mode of nutrition in them is either autotrophic or heterotrophic.
3. All of them are prokaryotic and thus they do not have well-formed nucleus. The nuclear membrane and the cell organelles are absent in them.
4. Kingdom Monera consists of different types of bacteria and blue-green algae.

E.g. Bacteria Clostridium titani, Vibrio choleri, Treponema pallidum, Streptococcus pneumoniae, Legionella pneumoniae, Salmonella typhi, Staphylococcus aureus, Clostridium botulinum.

6. Who am I?

Question a.
I don’t have true nucleus, cell organelles or plasma membrane.
Answer:
Microbe from Monera

Question b.
I have nucleus and membrane bound cell organelles.
Answer:
Protozoan from Protista/I am any one of Eukaryote

Question c.
I live on decaying organic matter.
Answer:
Fungus

Question d.
I reproduce mainly by cell division. (*Binary fission)
Answer:
Bacteria and some Protozoa.

Question e.
I can produce my replica.
Answer:
Virus

Question f.
I am green, but don’t have organs.
Answer:
Algae

7. Draw neat and labelled diagrams.

Question a.
Different types of bacteria:
Answer:

Question b.
Paramoecium:
Answer:

Question c.
Bacteriophage
Answer:

8. Arrange the following in ascending order of size Bacteria, Fungi, Viruses, Algae.

Question a.
Arrange the following ¡n ascending order of size Bacteria, Fungi, Viruses, Algae.
Answer:
Viruses, Bacteria, Fungi, Algae.

Project:

Question 1.
Prepare a chart showing infectious bacteria and the diseases caused by them.

Question 2.
Visit a nearby pathology lab. Get the information about pathogenic microbes, methods to observe them, different microscopes from the technicians there.

Class 8 Science Chapter 1 Living World and Classification of Microbes Additional Important Questions and Answers

Rewrite the sentences after filling the blanks:

Question 1.
The process of dividing living organism into groups and subgroups is called …………… .
Answer:
Biological classification.

Question 2.
Organisms with cell wall but not able to perform photosynthesis are called …………… .
Answer:
Fungi.

Question 3.
Most of the fungi are …………… .
Answer:
saprotrophic.

Question 4.
Viruses can be seen only with …………… .
Answer:
electron microscope.

Question 5.
…………… viruses attack bacteria.
Answer:
Bacteriophage

Question 6.
In fungi the cell wall is made up of j tough and complex sugar called …………… .
Answer:
‘Chitin’.

State whether the following statements are True or False. Explain your statement:

Question 1.
Plasmodium causes dysentery.
Answer:
False.
Explanation Plasmodium causes malaria. Entamoeba histolytica causes amoebic dysentery or amoebiasis.

Find out my partner

Question 1.

Answer:

Question 2.

Answer:

Question 3.

Answer:

Name the following/ Give examples

Question 1.
Three organs of locomotion in Protista
Answer:

1. Pseudopodia
2. Cilia
3. Flagella

Question 2.
Two autotrophic Protista
Answer:

1. Euglena
2. Volvox

Question 3.
Institute in India which is involved in research on viruses
Answer:
National Institute of Virology, Pune

Question 4.
Two methods of asexual reproduction in Fungi
Answer:

1. Binary fission
2. Budding

Question 5.
Two pathogenic protozoans and the diseases caused by them
Answer:

1. Entamoeba histolytica causes amoebiasis
2. Plasmodium vivax – causes malaria.

Answer the following questions in one sentence:

Question 1.
What are the types of living organisms according to their lifestyle?
Answer:
Producers, consumers and decomposers are the types of living organisms according to their lifestyle.

Question 2.
What are the characteristics of prokaryotic cells?
Answer:
Absence of nuclear membrane, well- formed nucleus and lack of cell organelles are the characteristics of the prokaryotic cells.

Question 3.
When do virus destroy the host cells?
Answer:
After synthesising their own proteins and creating numerous replica of their own type, then the virus destroys the host cells.

Give answers:

Question 1.
Which criteria were considered for classification method of Whittaker?
Answer:
The criteria considered for classification by Whittaker are as follows:
1. Complexity of cell structure: Whether the cells of the organisms are prokaryotic or eukaryotic.

2. Complexity of organisms Whether the organisms are unicellular or multicellular is considered.

3. Mode of nutrition Whether the organism is autotrophic and is performing photosynthesis on its own or it is heterotrophic is considered. Plants are autotrophic, fungi are saprotrophic while animals use food from plants or other animals and hence they are heterotrophic.

4. Lifestyle According to nutrition, every living organism is at certain trophic level. This is called lifestyle. Plants are producers, animals are consumers while fungi are decomposers.

5. Phylogenetic relationship When the evolution proceeded gradually, there was transition from prokaryotes to eukaryotes, unicellular to multicellular. In this order the different groups of living organisms were evolved. This is known as phylogenetic relationship.

Use your brain power!
(Textbook page 3)

Question 1.
Explain merits and demerits of Whittaker’s classification.
Answer:
I. Merits of Whittaker’s classification:

1. The classification system that Whittaker has adapted is totally based on scientific foundation.
2. Prokaryotes are placed separately in a different kingdom. The prokaryotic organisms are different from other organisms, thus placing them separately is justified.
3. All unicellular eukaryotic organisms are clubbed together in one kingdom named, Protista. This has helped to solve the placement of Euglena.
4. Euglena has chloroplasts like plants but as animals it has flagella and thus there was conflict about such species during previous classification systems. It was placed in protozoa previously.
5. Fungi are saprophytic and hence they are placed separately in a unique kingdom.
6. According to five kingdom classification, the cell structure, organization of cell, mode of nutrition, lifestyle and phylogenetic relationship are taken into consideration.
7. Therefore the system of 5 kingdom classification becomes most authentic system of biological classification.

II. Demerits of Whittaker’s method of classification:

1. Some organisms belonging to Monera and Protista have ability to perform photosynthesis. Thus they show mode of nutrition as autotrophic, while others are heterotrophic. Similarly some monerans have cell wall and some Protists also have cell wall. This becomes confusing during their placement.

2. In kingdom Protista, organisms show varied characteristics. In spite of this they are placed together.

3. In kingdoms, Plantae, Animalia and Fungi the organisms having primitive characters and were initial examples during evolution are not included. E.g. In Kingdom Animalia, amoeba is not included though it is said to be unicellular animal. This creates confusion.

4. Similarly if algae are unicellular, they are placed in kingdom Protista and if they are multicellular they are placed in kingdom Plantae. In reality, unicellular and multicellular algae both show much similarity. But due to Whittaker’s classification system they are placed away from each other.

5. Species of algae such as Chlorella, Chlamydomonas are not included in Kingdom Protista.

6. Viruses are not included in any of the kingdoms by Whittaker. Their classification has become a point of debate among the biologists.

Write short notes:

Question 1.
Characteristics of Fungi.
Answer:

1. The organisms which are placed in kingdom Fungi are multicellular, heterotrophic, non-green, and eukaryotic in nature.
2. Most of the fungi are saprophytic and they sustain on the dead and decaying organic matter.
3. The cell wall of the fungal cells is made up of chitin. Chitin is the tough and complex sugar.
4. Fungi have thread like body. The cytoplasm of the fungal cells contain many nuclei.
5. The reproduction in Fungi is either sexual or asexual. Asexual reproduction is by fission or by budding.
6. Examples Baker’s yeast, Candida, Mushroom, Aspergillus (Fungus on corn), Penicillium

Question 2.
Characteristics of Bacteria.
Answer:

1. Bacteria are microscopic, unicellular, prokaryotic organisms belonging to the kingdom Monera.
2. Some bacteria are solitary with independent existence. Some are colonial forms.
3. The bacterial cell lacks well-formed nucleus with nuclear membrane and cell organelles.
4. Reproduction is by binary fission.
5. In favourable conditions, bacteria duplicate with a great speed. Within 20 minutes they can double in number.
6. Bacteria may be round as in Cocci, elongated as in Bacillus, comma shaped as in Vibrio and spiral shaped as in Spirillum.

Question 3.
Characteristics of Protozoa.
Answer:

1. Protozoa are unicellular, eukaryotic organisms belonging to kingdom, Protista.
2. They are microscopic of the size of about 200 pm.
3. They have different organs of locomotion such as pseudopodia, cilia and flagella.?
4. Reproduction is by asexual method, usually by binary fission. .
5. Protozoa are seen in varied habitats such as soil, fresh water and marine water.
6. Some protozoans are parasitic and cause various types of illness in hosts. E.g. Entamoeba histolytica is a species of amoeba that causes amoebiasis. Malaria is caused by Plasmodium vivax.
7. Protozoa show different modes of nutrition.

E.g. Euglena is autotrophic as it does photosynthesis with the help of 5 chloroplasts present in its body. Amoeba and Paramoecium are heterotrophic and free living seen in contaminated water.

Complete the paragraph using the words given in the brackets

[Monera, Euglena, autotrophic, cell organelles, chitin, nuclear, prokaryotic, viruses, replicas, saprotrophic, viral particles]

In Kingdom ……….. bacteria were included but not ………….. Viruses are on the border line of living and non-living. Do we really call them living? If they are making …………. of their own type, are they not considered as living? Throughout the world they spread hazardous epidemics. Antibiotics do not act on ………… However, bacteria can be controlled by antibiotics. All the living organisms belonging to Monera are with …………… cell. They do not have ………….. membrane and neither they have ……………… But a nice nucleus is seen in …………….., Euglena is ………… protist. The fungi with cell wall of …………….. are ………….. in their mode of nutrition.
Answer:
In Kingdom Monera bacteria were included but not viruses. Viruses are on the border line of living and non-living. Do we really call them living? If they are making replicas of their own type, are they not considered as living? Throughout the world they spread hazardous epidemics. Antibiotics do not act on viral particles. However, bacteria can be controlled by antibiotics. All the living organisms belonging to Monera are with prokaryotic cell. They do not have nuclear membrane and neither they have cell organelles. But a nice nucleus is seen in Euglena. Euglena is autotrophic protist. The fungi with cell wall of chitin are saprotrophic in their mode of nutrition.

Complete the chart:

Question 1.
Draw a chart showing different types of Microorganisms.
Answer:

Draw neat and labelled diagrams: 

Question 1.
Fungi:
Answer:

Question 2.
Euglena:
Answer:

Question 3.
Amoeba:
Answer:

Question 4.
Correctly label the various organisms shown in the Kingdom Monera:

Answer:

1. Streptococcus pneumoniae
2. Clostridium titani
3. Vibrio choleri
4. Treponema pallidum
5. Staphylococcus aureus
6. Legionella pneumoniae
7. Salmonella typhi
8. Clostridium botulinum

Activity-based questions

1. Try this:
Activity Take a small drop of curd or buttermilk on a clean glass slide. Dilute it with a little water. Carefully keep a coverslip. Observe it under high power of compound microscope. What did you see?
Answer:
In the slide we can see Lactobacilli \ bacteria.

2. Try this: 
Activity Prepare a temporary mount of one drop of pond water on a glass slide. Observe it under low power and high power microscope.
Answer:
The drop on the slide shows motile microscopic organisms which have irregular shape. They are amoeba.

3. Try this: 
Activity Take a moist piece of bread or bhakri and keep it in a container with lid for 2-3 days. After 2-3 days a fine cotton thread like tuft is found growing on the surface of the bread. Prepare a temporary mount of few threads from this culture and observe it under the microscope.
Answer:
Upon observation of thread like structures the fungal hyphae ( fibre like body) are seen.

MCQs based on experiments:

Choose the appropriate alternative of the following:

Experiment 1: To observe lactobacilli in curd/buttermilk.

Question 1.
Which of the following bacterium is used to make curds from milk?
(a) Streptococcus
(b) Lactobacillus
(c) Staphylococcus
(d) Clostridium
Answer:
(b) Lactobacillus

Question 2.
In which kingdom is Lactobacillus included?
(a) Monera
(b) Protista
(c) Fungi
(d) Plantae
Answer:
(a) Monera

Question 3.
Which is the other organism that has been added in kingdom Monera in addition to bacteria?
(a) Virus
(b) Blue-green algae
(c) Fungi
(d) Protozoa
Answer:
(b) Blue-green algae

Experiment 2: To observe fungus on the bread

Question 1.
In which kingdom is fungus growing on the bread included?
(a) Fungi
(b) Protozoa
(c) Monera
(d) Protista
Answer:
(a) Fungi

Question 2.
What are dark coloured particles which are seen when the fungus is growing on the bread?
(a) Sporangiophore
(b) Rhizoids
(c) spores
d) Columella
Answer:
(c) spores

Question 3.
Why is there growth of fungus on all the stale food?
(a) Fungus has affinity for food.
(b) Fungus grows on decaying organic matter.
(c) As food is open, the fungus drops on it and starts growing.
(d) None of the alternative is correct.
Answer:
(b) Fungus grows on decaying organic matter.

Balbharati Maharashtra State Board 8th Std Science Textbook Solutions 

• Living World and Classification of Microbes Class 8 Science Textbook Solutions
• Health and Diseases Class 8 Science Textbook Solutions
• Force and Pressure Class 8 Science Textbook Solutions
• Current Electricity and Magnetism Class 8 Science Textbook Solutions
• Inside the Atom Class 8 Science Textbook Solutions
• Composition of Matter Class 8 Science Textbook Solutions
• Metals and Nonmetals Class 8 Science Textbook Solutions
• Pollution Class 8 Science Textbook Solutions
• Disaster Management Class 8 Science Textbook Solutions
• Cell and Cell Organelles Class 8 Science Textbook Solutions

Std 8 Science Chapter 13 Chemical Change and Chemical Bond Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 13 Chemical Change and Chemical Bond Notes, Textbook Exercise Important Questions and Answers.

Class 8 Science Chapter 13 Chemical Change and Chemical Bond Question Answer Maharashtra Board

Class 8 Science Chapter 13 Chemical Change and Chemical Bond Textbook Questions and Answers

1. Complete the statement by filling the gaps using appropriate term from the terms given in the brackets:
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)

Question a.
An ……….. is drawn in between the reactants and products while writing the equation for a chemical reaction.
Answer:
An arrow is drawn in between the reactants and products while writing the equation for a chemical reaction.

Question b.
Rusting of iron is a ……….. chemical change.
Answer:
Rusting of iron is a slow chemical change.

Question c.
The spoiling of food is a chemical change which is recognized from the generation of certain …………. due to it.
Answer:
The spoiling of food is a chemical change which is recognized from the generation of certain smell due to it.

Question d.
A colourless solution of calcium hydroxide in a test tube turns ………….. on blowing in it through a blow tube for some time.
Answer:
A colourless solution of calcium hydroxide in a test tube turns milky on blowing in it through a blow tube for some time.

Question e.
The white particles of baking soda disappear when put in lemon juice. This means that it is a ……….. change.
Answer:
The white particles of baking soda disappear when put in lemon juice. This means that it is a chemical change.

Question f.
Oxygen is a …………….. in respiration.
Answer:
Oxygen is a reactant in respiration.

Question g.
Sodium chloride is …………… compound while hydrogen chloride is compound.
Answer:
Sodium chloride is ionic compound while hydrogen chloride is covalent compound.

Question h.
Electron …………….. is complete in each hydrogen in a hydrogen molecule.
Answer:
Electron duplet is complete in each hydrogen in a hydrogen molecule.

Question i.
Chlorine (Cl₂) molecule is formed by ………….. of electrons between two chlorine atoms.
Answer:
Chlorine (Cl₂) molecule is formed by sharing of electrons between two chlorine atoms.

2. Explain by writing a word equation. 

Question a.
Respiration is a chemical change.
Answer:
Respiration is a biological process, in this process air is inhaled, oxygen present in this inhaled air reacts with glucose present in the cells of the body forming carbon dioxide and water. Moreover, we cannot obtain glucose and oxygen from carbon dioxide and water. Hence, respiration is a chemical change.
Word equation:

Question b.
Hard water gets softened on mixing with a solution of washing soda.
Answer:
Hard water does not form lather with soap and is brackish to taste. This is because hard water contains the chloride and sulphate salts of calcium and magnesium in dissolved state. When a solution of washing soda is added to hard water, it forms a precipitate of calcium carbonate and magnesium carbonate, which is removed by filtration thus water is softened.
Word equation:

Question c.
Limestone powder disappears on adding to dilute hydrochloric acids.
Answer:
In the reaction of dil. HCl and limestone powder (CaCO₃), limestone disappears slowly and carbon dioxide (CO₂) liberates slowly.
Word equation:

Question d.
Bubbles are seen on adding lemon juice to baking soda.
Answer:
When baking soda is added to lemon juice a chemical change takes place in citric acid present in the lemon juice and carbon dioxide gas is formed. Word equation:

This is a neutralization reaction.

3. Match the pairs.

Question a.

Answer:

4. Show with the help of diagram of electronic configuration how the following compounds are formed from the constituent atoms.

Question a.
Sodium Chloride:

Answer:
1. Sodium has atomic number 11 and electronic configuration 2, 8, 1.
2. Sodium atom has 1 electron in its outermost shell.

3. It loses one electron from its outermost shell, i.e., M shell. Then its L shell becomes the outermost shell with a stable octet. The nucleus of sodium atom has 11 protons but the number of electrons in the atom has become 10. So, there is a net unit positive charge giving a sodium cation (Na⁺).

4. On the other hand, chlorine has electronic configuration 2, 8, 7. Chlorine atom has 7 electrons in its outermost shell and requires one electron to complete its octet.
5. Thus, the electron lost by sodium is taken up by chlorine.

6. When chlorine atom gains one electron, octet of chlorine is completed and its K, L, M shells have together 18 electrons and the nucleus has 17 protons. This leads to the formation of an ion (CP).

7. Thus, a chlorine atom accepts one electron from a sodium atom and consequently a chloride ion with one unit negative charge and a sodium ion with one unit positive charge are formed.

8. Sodium and chloride ions, being oppositely charged, attract each other due to the electrostatic force of attraction. An ionic bond is formed and this results in the formation of sodium chloride (NaCl) molecule.

Question b.
Potassium fluoride:
Answer:
1. Potassium has atomic number 19 and electronic configuration 2, 8, 8, 1.
2. Potassium atom has 1 electron in its outermost shell.

3. It loses one electron from its outermost shell, i.e. N shell. Then its M shell becomes the outermost shell with a stable octet. The nucleus of potassium atom has 19 protons but the number of electrons in the atom has become 18. So there is a net unit positive charge giving a potassium cation (K⁺).

4. On the other hand, fluorine has electronic configuration 2, 7. Fluorine has 7 electrons in the outermost shell and requires one electron to complete its octet.

5. Thus, the electron lost by potassium is taken up by chlorine.

6. When fluorine atom gains one electron, octet of fluorine is completed, its K and L shells have together 10 electrons and the nucleus has 9 protons. This leads to the formation of an ion (F^–).

7. Thus, a fluorine atom accepts one electron from a potassium atom and consequently a fluoride ion with one unit negative charge and a potassium ion with one unit positive charge are formed.

8. Potassium and fluoride ions, being oppositely charged, attract each other due to electrostatic force of attraction. An ionic bond is formed and this results in the formation of potassium fluoride (KF) molecule.

Question c.
Water:
Answer:

1. Hydrogen has atomic number 1 and electronic configuration 1.
2. Hydrogen has 1 electron in its K shell.

3. Oxygen has atomic 8 and electronic configuration 2, 6. There are 6 electrons in the valence shell of oxygen atom. It means that the electron octet in oxygen is short of two electrons and the valency of oxygen is two.

4. In the H₂O molecule, the oxygen atom complete its octet by sharing two electrons one each with two hydrogen atoms, thus, forming two covalent bonds. While this happens, the duplets of two hydrogen atoms are completed.

Question d.
Hydrogen chloride:
Answer:
1. Hydrogen has atomic number 1 and electronic configuration 1, that means it has 1 electron in its K shell and its duplet is short of one electron therefore, the valency of hydrogen is one.

2. On the other hand, chlorine has electronic configuration 2, 8, 7. Chlorine atom has 7 electrons in its outermost shell and requires one electron to complete its octet.

3. The two atoms, hydrogen and chlorine share one electron with each other. As a result, the electron duplet of hydrogen and octet of chlorine is complete and a covalent band is formed between them.

Can you recall?

Question a.
What are the methods of classification of changes?
Answer:
The methods of classification of changes: Physical change and chemical change.

Question b.
What is the difference between physical and chemical change?
Answer:

1. In physical change, the composition of substance does not change. No new substance is formed.
2. In chemical change, the composition of compounds change and new compounds are formed.

Question c.
Classify the following changes into physical and chemical change. Ripening of mango, melting of ice, boiling of water, dissolution of salt in water, Ripening of banana, fragrance on ripening fruit, darkening of a cut potato, bursting of an inflated balloon, sound of bursting fire cracker, foul smell from a portion of spoiled food.
Answer:

• Physical change: Melting of ice, boiling of water, dissolution of salt in water.
• Chemical change: Ripening of mango, ripening of banana, fragrance of ripening fruit, darkening of a cut potato, bursting of an inflated balloon, sound of bursting firecracker, foul smell from a spoiled food.

Project:

Question a.
Prepare a list of the chemical changes that occur in your house and surroundings and discuss these in the class.

Class 8 Science Chapter 13 Chemical Change and Chemical Bond Important Questions and Answers

Fill in the blanks:

Question 1.
……………. is a continuously occurring biological process.
Answer:
Respiration is a continuously occurring biological process.

Question 2.
The reaction between citric acid and sodium bicarbonate is a ……………. reaction.
Answer:
The reaction between citric acid and sodium bicarbonate is a neutralization reaction.

Question 3.
Combustion of fuel is a ………… and ……………. chemical change.
Answer:
Combustion of fuel is a fast and irreversible chemical change.

Question 4
Electronic configuration of sodium is …………….
Answer:
Electronic configuration of sodium is 2, 8, 1.

Question 5.
Electronic configuration of chlorine is …………….
Answer:
Electronic configuration of chlorine is 2, 8, 7.

Question 6.
A chemical bond formed by sharing of valence electrons of two atoms with each other is called a …………….
Answer:
A chemical bond formed by sharing of valence electrons of two atoms with each other is called a covalent bond.

Question 7.
Hard water contains the chloride and sulphate salts of ……………. and ……………. in dissolved state.
Answer:
Hard water contains the chloride and sulphate salts of calcium and magnesium in dissolved state.

Question 8.
Electronic configuration of fluorine is …………….
Answer:
Electronic configuration of fluorine is 2, 7.

Question 9.
Green plants perform ……………. in sunlight.
Answer:
Green plants perform photosynthesis in sunlight.

Question 10.
Melting of ice is a ……………. change.
Answer:
Melting of ice is a physical change.

Question 11.
The chloride ion has a ……………. charge.
Answer:
The chloride ion has a negative charge.

Question 12.
A covalent bond between two atoms is also represented by ……………. joining their symbols.
Answer:
A covalent bond between two atoms is also represented by dash joining their symbols.

Rewrite the following statements by selecting the correct options:

Question 1.
Sodium atoms and sodium ions ………….. .
(a) are chemically the same
(b) have the same number of protons
(c) have the same number of electrons
(d) form covalent bond
Answer:
(b) have the same number of protons

Question 2.
An ionic bond is formed when …………….. .
(a) two metallic elements react
(b) two nonmetallic elements react
(c) a metallic element reacts with a non-metallic element
(d) a pair of elements react
Answer:
(c) a metallic element reacts with a non-metallic element

Question 3.
…………….. tries to establish the duplet state in its outermost orbit by sharing electrons.
(a) Sodium
(b) Potassium
(c) Hydrogen
(d) Magnesium
Answer:
(c) Hydrogen

Question 4.
…………… is an electron donor.
(a) Helium
(b) Iodine
(c) Chlorine
(d) Magnesium
Answer:
(d) Magnesium

Question 5.
………………. combine to form an ionic compound.
(a) Hydrogen and chlorine
(b) Hydrogen and oxygen
(c) Potassium and chlorine
(d) Nitrogen and oxygen
Answer:
(c) Potassium and chlorine

Question 6.
……………. is an example of chemical change.
(a) Magnetism of iron
(b) Rusting of iron
(c) Heating of iron till it becomes red hot
(d) Dissolution of salt in water
Answer:
(b) Rusting of iron.

State whether the following statements are True or False. (If a statement is false, correct it and rewrite it.)

Question 1.
The preparation of cold drink soda- lemon is a physical change.
Answer:
False. [The preparation of cold drink soda-lemon is a chemical change.]

Question 2.
Hard water contains the chloride and sulphate salts of calcium and magnesium in dissolved state.
Answer:
True.

Question 3.
Combustion of fuel is a fast and irreversible man-made chemical change.
Answer:
True.

Question 4.
Photosynthesis reaction is a man-made chemical change.
Answer:
False. [Photosynthesis reaction is a natural chemical change.]

Question 5.
The atoms with incomplete electron octet/duplet form chemical bonds.
Answer:
True.

Question 6.
Electronic configuration of chlorine is 2, 8, 6.
Answer:
False. (Electronic configuration of chlorine is 2, 8, 7.)

Question 7.
One ionic bond is formed due to the electrical change +1 or -1 on an ion.
Answer:
True.

Question 8.
H₂O Molecule is an ionic compound.
Answer:
False. (H₂O molecule is a covalent compound.)

Question 9.
The bond between two chlorine atoms is a covalent band.
Answer:
True.

Question 10.
Arrow indicates the direction of the reaction.
Answer:
True.

Consider the correlation between the words of the first pair, match the third word/words with the most appropriate answer:

Question 1.
K : 2, 8, 8, 1 : : Mg : ………………
Answer:
2, 8, 2

Question 2.
MgCl₂ : Ionic bond : : CaO : ……………..
Answer:
Covalent bond

Question 3.
Photosynthesis : Natural chemical change : : Cold drink, soda lemon : ………
Answer:
Man-made chemical change

Question 4.
Respiration: Glucose + Oxygen : : Neutralization : ………….
Answer:
Acid + alkali.

Match the columns:

Question 1.

Answer:

Define the following:

• Chemical change: In a chemical change, the chemical composition of the original matter changes and new substances having different properties and different chemical composition are formed.
• Ionic bond: The chemical bond formed due to an electrostatic force of attraction between the oppositely charged cation and anion is called an ionic bond or an electrovalent bond.
• Covalent bond: The chemical bond formed by sharing of valence electrons of two atoms with each other is called a covalent bond.

Answer the following questions in one sentence each:

Question 1.
Name the reactants in respiration.
Answer:
Glucose and oxygen are the reactants in respiration.

Question 2.
Name the products of respiration.
Answer:
Carbon dioxide and water are the products of respiration.

Question 3.
Name the reactants in photosynthesis.
Answer:
Carbon dioxide and water are the reactants in photosynthesis.

Question 4.
Name the products of photosynthesis.
Answer:
Glucose and oxygen are the products of photosynthesis.

Question 5.
Name the salts present in hard water.
Answer:
Salts present in hard water are calcium chloride, magnesium chloride, calcium sulphate and magnesium sulphate.

Question 6.
Give two examples of ionic compounds.
Answer:
Ionic compounds: Sodium chloride (NaCl), Potassium fluoride (KF).

Question 7.
Give two examples of covalent compounds.
Answer:
Covalent compounds: Hydrogen (H₂), Water (H₂O).

Question 8.
Name an acid used for cleaning Shahabad tile.
Answer:
An acid used for cleaning Shahabad tile is dilute hydrochloric acid (HCl).

Question 9.
Write a chemical equation for combustion of fuel.
Answer:
Chemical equation:
C + O₂ → CO₂

Question 10.
Write a chemical equation for photosynthesis.
Answer:
Chemical equation:

Answer the following questions:

1. Explain by writing a word equation.

Question 1.
Combustion of fuel is a fast and irreversible chemical change.
Answer:
Wood, coal, petrol or cooking gas are burnt for producing energy. Carbon is the common substance that burns in all these fuels. The product carbon dioxide is formed when carbon combines with oxygen in the air during the combustion process. We cannot obtain fuel from carbon dioxide by employing any other method. Properties of carbon dioxide are altogether different from those of fuel. Hence, this change is a irreversible chemical change.
Word equation:
Carbon + Oxygen → Carbon dioxide

Question 2.
Dilute hydrochloric acid is used for cleaning Shahabad tiles.
Answer:
The main constituent of Shahabad tile is calcium carbonate. During its cleaning with hydrochloric acid, the upper layer of the tile reacts with hydrochloric acid and three products are formed. One of them is calcium chloride, which being soluble in water, gets washed away with water. The second product is carbon dioxide, it mixes with air. The third product is water.
Word equation:

2. Write a chemical equation (unbalanced) for the following reactions:

Question 1.

Answer:
Chemical equation:
CO₂ + Ca(OH)₂ → CaCO₃ + H₂O

Question 2.

Answer:
Chemical equation:
CaCO₃ + HCl → CaCl₂ + CO₂ + H₂O

Question 3.
Magnesium salts during the softening of hard water.

Answer:
Chemical equation:
MgCl₂ + Na2CO₃ → MgCOg + 2NaCl

3. Show with the help of diagram of electronic configuration how the following compounds are formed from the constituent atoms.

Question 1.
Hydrogen molecule:
Answer:
1. Hydrogen has atomic number 1 and electronic configuration 1. That means it has 1 electron in its K shell and its duplet is short of one electron therefore, the valency of hydrogen is one.

2. The two atoms of hydrogen are identical, they share their electrons with each other.
3. As a result, the electron duplet of both the hydrogen atoms is complete and a covalent band is formed between them.

4. There is one covalent bond between the component atoms H and Cl of the molecule HCl. Use this information to represent the formation of HCl molecules from H and Cl atoms diagrammatically.
(Use your brainpower)
Answer:
Hydrogen chloride:
1. Hydrogen has atomic number 1 and electronic configuration 1, that means it has 1 electron in its K shell and its duplet is short of one electron therefore, the valency of hydrogen is one.

2. On the other hand, chlorine has electronic configuration 2, 8, 7. Chlorine atom has 7 electrons in its outermost shell and requires one electron to complete its octet.

3. The two atoms, hydrogen and chlorine share one electron with each other. As a result, the electron duplet of hydrogen and octet of chlorine is complete and a covalent band is formed between them.

5. Show the formation of the following ionic compounds from the corresponding elements using two methods namely, numerical and diagrammatic representation of electronic configuration.
(a) K⁺ F^–, from 19K and 9F, (b) Ca²⁺ O^2- from ₂₀Ca and ₈O.
(Use your brainpower)
Answer:
(a) K⁺F^– from ₁₉K and ₉F
Potassium fluoride:
1. Potassium has atomic number 19 and electronic configuration 2, 8, 8, 1.
2. Potassium atom has 1 electron in its outermost shell.

3. It loses one electron from its outermost shell, i.e. N shell. Then its M shell becomes the outermost shell with a stable octet. The nucleus of potassium atom has 19 protons but the number of electrons in the atom has become 18. So there is a net unit positive charge giving a potassium cation (K⁺).

4. On the other hand, fluorine has electronic configuration 2, 7. Fluorine has 7 electrons in the outermost shell and requires one electron to complete its octet.

5. Thus, the electron lost by potassium is taken up by chlorine.

6. When fluorine atom gains one electron, octet of fluorine is completed, its K and L shells have together 10 electrons and the nucleus has 9 protons. This leads to the formation of an ion (F^–).

7. Thus, a fluorine atom accepts one electron from a potassium atom and consequently a fluoride ion with one unit negative charge and a potassium ion with one unit positive charge are formed.

8. Potassium and fluoride ions, being oppositely charged, attract each other due to electrostatic force of attraction. An ionic bond is formed and this results in the formation of potassium fluoride (KF) molecule.

(b) Ca²⁺O^2- from ₂₀Ca and ₈O.

Distinguish between the following:

Question 1.
Physical change and Chemical change:
Answer:

Question 2.
Ionic bond and Covalent bond:
Answer:

Give scientific reasons:

Question 1.
Ionic compounds are formed due to the combination of metallic and nonmetallic atoms.
Answer:
Metallic atoms have a tendency to lose electrons from their outermost orbits to establish the octet state in their penultimate orbits. Conversely, nonmetallic atoms gain electrons to establish the octet state of their outermost orbits.

When a metallic atom and a nonmetallic atom come close together, the metallic atom loses electrons and gets c converted into positively charged ion, while the nonmetallic’ atom gets converted into negatively charged ions so formed, develop an ionic bond and this results in the formation of an ionic compound. Hence, ionic compounds are formed due to the combination of metallic and nonmetallic atoms.

Activity-based questions:

Activity 1:

Take the lemon juice in a clean glass. Take two drops of the lemon juice in a spoon and taste. Add a pinch of baking soda in the glass of lemon juice. Did you notice bubbling around the particles of soda? Did you hear a sound on taking your ear near the glass? Now again taste it. Did it taste as sour as it was in the beginning? (Above activity is to be done using clean apparatus and edible material. Then only it is possible to test the ’taste’, otherwise keep in mind that the testing of ‘taste’ cannot be done.)

Activity 2:
Take some freshly prepared lime water (solution of calcium hydroxide) in a test tube. Keep on blowing in it with a blow tube. What is seen after some time? Did the colourless lime water turn milky? After some more time you will find that a white insoluble solid settles at the bottom of the test tube. This is a precipitate of calcium carbonate. The turning lime water milky means that the blown gas mixed in it was carbon dioxide.

Write a chemical equation for the above word equation.
Chemical equation:
CO₂ + Ca(OH)₂ → CaCO₃ + H₂O

Balbharati Maharashtra State Board 8th Std Science Textbook Solutions

• Human Body and Organ System Class 8 Science Textbook Solutions
• Introduction to Acid and Base Class 8 Science Textbook Solutions
• Chemical Change and Chemical Bond Class 8 Science Textbook Solutions
• Measurement and Effects of Heat Class 8 Science Textbook Solutions
• Sound Class 8 Science Textbook Solutions
• Reflection of Light Class 8 Science Textbook Solutions
• Man-made Materials Class 8 Science Textbook Solutions
• Ecosystems Class 8 Science Textbook Solutions
• Life Cycle of Stars Class 8 Science Textbook Solutions

Std 8 Science Chapter 2 Health and Diseases Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 2 Health and Diseases Notes, Textbook Exercise Important Questions and Answers.

Class 8 Science Chapter 2 Health and Diseases Question Answer Maharashtra Board

Class 8 Science Chapter 2 Health and Diseases Textbook Questions and Answers

1. Distinguish between- Infectious and non – infectious diseases.

2. Identify the odd term. 

Question a.
Malaria, hepatitis, elephantiasis, dengue.
Answer:
Hepatitis (All other diseases are caused by the carrier mosquito.)

Question b.
Plague, AIDS, Cholera, T.B.
Answer:
AIDS [All others are bacterial (caused by bacteria) diseases.]

3. Answer in one to two sentences.

Question a.
Which are various media of spreading the infectious diseases?
Answer:
Infectious diseases spread through contaminated air, water, food, vectors such as insects, animals and man.

Question b.
Give the names of five non-infectious diseases other than given in the lesson.
Answer:
Asthma, cataract, diseases of kidney such as kidney stones and renal failure, arthritis, Alzheimer which is a condition during old age, hypertension, migraine, etc.

Question c.
Which are the main reasons of diabetes and heart diseases?
Answer:
Improper lifestyle, wrong type of diet, lack of exercise, excessive mental stress and strain, imbalance in secretion of hormones, etc. are the main reasons for diabetes and heart diseases.

4. What can be achieved/can be prevented?

Question a.
Drinking boiled and filtered water.
Answer:

1. When water is boiled, all the disease causing pathogens present in it are killed.
2. Different diseases like cholera, enteritis, diarrhoea, dysentery, hepatitis, typhoid are caused by such water-borne pathogens.
3. If we boil the water we are protected against all such diseases.
4. If the i water is filtered we can avoid infections from nematode Dracunculus which causes Naru. By boiling and filtering water, even the epidemics by such infectious diseases can be controlled.

Question b.
Avoiding smoking and alcoholism.
Answer:
1. Smoking and alcoholism are two dangerous habits that cause addictions. Alcoholism causes disorders of liver.
2. The addict suffers from malnourishment.

3. His I mental and psychological conditions become abnormal. There is social and familial) impacts too due to alcoholistn.

4. Smoking is an invitation for cancer. In cigarettes/ bidis, there is hazardous nicotine. Nicotine is not only toxic but is also carcinogenic. Cancers of oral cavity, tongue, respiratory tract, lungs is very common among smokers. Therefore, addictions like smoking and alcoholism should always be avoided.

Question c.
Regular balanced diet and exercise.
Answer:
1. Regular and balanced diet results into perfect health. The disease fighting power or immunity of a person is increased due to healthy diet.
2. One can avoid of frequent infections and also mental well¬being is established.
3. Heart disease, diabetes, obesity, etc. can be avoided by not consuming high caloric junk food.
4. Exercise improves blood circulation. Many disorders which are caused by faulty lifestyle can be prevented by having regular balanced diet and exercise, thus one must always follow these for well-being.

Question d.
Proper checking of blood before blood donation.
Answer:
1. There are definite blood groups.
2. During blood transfusion, the donor’s and recipient’s blood should be well-matched with each other. Otherwise, blood gets clumped inside the body of recipient.
3. Through infected blood, the viruses such as those causing hepatitis B or AIDS are transmitted to other healthy persons. Thus, for prevention of transmission of such diseases, blood should be checked before blood donation.

5. Read the passage and answer the questions.

Master X’ is a 3-year-old child. He is living with his family in a slum. The public toilet is present near his house. His father is drunkard. His mother does not know the importance of balanced diet.

Question a.
Master ‘X’ can suffer from which different possible diseases in above conditions?
Answer:
Master ‘X’ stays in an area which is devoid of cleanliness. The public toilet is near his house. This indicates that he will have to fight against many infectious diseases. Because his father is a drunkard, there will always be a dearth of money in r the house. He may not be able to afford, enough and balanced food. Thus his diet must be deficient in vitamins and minerals.

Moreover, his mother is ignorant about the importance of health and a balanced diet. This must be causing Master ‘X’ malnourishment and loss of immunity. The financial conditions and the addition of the father must be causing stress in the house.

This will further add stress on Master ‘X’ resulting into susceptibility to infections. As it is due to the location the germs are around and thus they may be attacking Master ‘X’. He will on and off suffer from digestive disorders! such as typhoid, hepatitis, cholera, enteritis, etc.

Question b.
How will you help him and his family in this situation?
Answer:
Initially, we shall help Master ‘X’ to procure healthy and balanced diet having fruits, vegetables, milk, etc. His mother will be taught importance of the balanced diet. The surroundings should be clean and hygienic. Food should be covered, houseflies should not be allowed to contaminate the food. Germicidal floor cleaners and disinfectants should be used to keep off the houseflies and cockroaches. His father will be taken to de-addiction centres such as ‘Alcoholics Anonymous’. He will be persuaded to leave alcoholism.

Question c.
Which disease can occur to the i father of master ‘X’?
Answer:
Father of Master ‘X’ can develop diseases of liver and kidney.

6. Give the preventive measures of following diseases:

Question a.
Dengue:
Answer:
Dengue is transmitted through bite of mosquito of Aedes aegypti. DEN-1, 2 virus belonging to the type – flavivirus is the causative pathogen for Dengue. Wherever there is stagnant or accumulated water, there is possibility of mosquito breeding. Therefore, care is to be taken to drain of such water. Thus this is a very important preventive measure. Especially, in the man¬made containers and in clean water, the Aedes mosquito prefers to breed.

Therefore, such water storages should be either covered or should be decanted. Another way to keep off from dengue is to increase our immunity to fight against the virus. There is vaccine called CYD-TDV or Dengvaxia which is synthesised in 2017. But it is still not considered to be completely safe.

Question b.
Cancer:
Answer:
The most important preventive measure is to remain away from the carcinogenic substances. Tobacco, gutkha, cigarette, bidi, etc. are addictive things which are very bad for our health. The nicotine present in these cause cancers of oral cavity and of respiratory system. Radiations can also cause cancer.

We should not expose ourselves to hazardous radiations. Balanced and healthy diet, proper exercise and living stress free with mental balance are some of the preventive measures of the cancer. Only for few types of cancer like cervical cancer in women, vaccine has been developed.

Question c.
AIDS:
Answer:
When blood transfusion is done, the blood should be checked for the presence of HIV. The used syringes, needles, etc. should not be used without sterilization. Through blood and blood products and body fluids HIV finds its way into the body. Therefore, these precautions should be taken. Unsafe sexual contact is the most important mode of transmission of HIV. Thus one should never deal with such dangerous acts. Awareness about AIDS and HIV is the real preventive measure.

7. Explain the importance.

Question a.
Balanced diet.
Answer:
The diet that contains all the nutrients in the balanced proportion is called balanced diet. One can avoid malnutrition by taking balanced diet. The immunity increases due to balanced diet containing good proportion of vitamins and minerals. Some diseases can be avoided due to raised immunity. Wrong lifestyle and wrong diet can cause hypertension, diabetes or heart disease. To maintain our health and keep the body in equilibrium, we have to take balanced diet.

Question b.
Physical exercise/Yogasanas.
Answer:
By exercise and yoga, the blood circulation of body is improved. Body and joints remain flexible. Mental strain and stress is reduced. Insomnia (inability to fall asleep), arthritis, indigestion, and some other disorders can be avoided. The person who performs exercise, always remains away from the addictions. Yoga makes levels of hormones, enzymes, etc. in equilibrium. By keeping control over breathing through pranayama many respiratory and circulatory disorders can be prevented.

8. Make a list. 

Question a.
Viral diseases.
Answer:
AIDS, Hepatitis, Influenza, Rabies, Polio.

Question b.
Bacterial diseases.
Answer:
Typhoid, Tuberculosis, Cholera, Leprosy.

Question c.
Diseases spread through insects.
Answer:
Malaria, Dengue, Elephantiasis.

Question d.
Hereditary diseases.
Answer:
Diabetes, Haemophilia, Muscular dystrophy, Colourblindness.

9. Write the information on modern diagnostics and treatments of cancer.

Question a.
Answer:
1. Following methods are used as diagnostic methods to detect the cancer. Techniques like CT scan, MRI scan, mammography, biopsy.
Treatment of the cancer is done by the following methods:

2. For treatment of cancer, some conventional methods are used. Along with these methods, chemotherapy, radiation therapy and surgery are commonly used to treat cancerous growth and tumours. New and modern techniques of robotic and laparoscopic surgery are also used for the treatment.

10. Enlist the names and composition of the medicines present at your home.

Question 1.
Prepare posters giving information about various diseases, public awareness and arrange exhibition in school.

Question 2.
Visit the public health center/clinic nearby and collect the information about vaccination.

Question 3.
Compose a street-play to increase public awareness about dengue, malaria, swine flu and present ¡tin the area nearby your school.

Project:

Question 1.
Prepare posters giving information about various diseases, public awareness and arrange exhibition in school.

Question 2.
Visit the public health center/clinic nearby and collect the information about vaccination.

Question 3.
Compose a street-play to increase public awareness about dengue, malaria, swine flu and present it in the area nearby your school.

Class 8 Science Chapter 2 Health and Diseases Additional Important Questions and Answers

Rewrite the sentences after filling the blanks:

Question 1.
For eradication of tuberculosis everybody should be vaccinated by …………. vaccine.
Answer:
For eradication of tuberculosis everybody j should be vaccinated by B.C.G vaccine.

Question 2.
Hepatitis B can be transmitted by ………….
Answer:
Hepatitis B can be transmitted by blood transfusion.

Question 3.
For treating diarrhoea/dysentery…………. is given to the patient.
Answer:
For treating diarrhoea/dysentery O.R.S. is given to the patient.

Question 4.
…………. virus is responsible for the infection of swine flu.
Answer:
Influenza A (H1N1) virus is responsible for the infection of swine flu.

Question 5.
…………. mosquito spreads dengue.
Answer:
Aedes aegypti mosquito spreads dengue.

Question 6.
Malaria is caused by female mosquito of …………. genus.
Answer:
Malaria is caused by female mosquito of Anopheles genus.

Question 7.
…………. test is performed on blood to diagnose AIDS.
Answer:
ELISA test is performed on blood to diagnose AIDS.

One word in the following sentences is wrong. Change it to make the sentences correct:

Question 1.
Culex mosquito is seen in clean water.
Answer:
Culex mosquito is seen in dirty water.

Question 2.
Transmission of swine flu is done by dogs and human beings.
Answer:
Transmission of swine flu is done by pigs and human beings.

Question 3.
Hydrophobia is the main symptom of typhoid.
Answer:
Hydrophobia is the main symptom of rabies.

Question 4.
The maximum number of patients of diabetes are found in America.
Answer:
The maximum number of patients of diabetes are found in India.

Question 5.
Generic medicines are also called branded medicines.
Answer:
Generic medicines are also called general medicines.

Question 6.
If the secretion of insulin is increased, then the diabetes is caused.
Answer:
If the secretion of insulin is decreased, then the diabetes is caused.

Question 7.
Virus causing rabies enter the brain through food.
Answer:
Virus causing rabies enter the brain through neurons.

Match the columns:

Question 1.

Answer:

Question 2.

Answer:

Identify the odd term:

Question 1.
Chemotherapy, Radiation therapy, Surgery, Pranayama
Answer:
Pranayama (All others are treatment for cancer.)

Question 2.
Chronic cough, Hoarse voice, Uncontrolled blood sugar level, Difficulty in swallowing.
Answer:
Uncontrolled blood sugar level (All others are symptoms of cancer of throat.)

Question 3.
Mantra, Vaccination, Black magic, Hatred.
Answer:
Vaccination (This is the only way for prevention of diseases. Rest of the others are blind faiths which are unscientific.)

Consider the relation between the items in the first pair and write the correlation for second pair:

1. Swine flu : Virus : :
Tuberculosis : : …………….
Answer:
Bacteria

2. Anopheles : Malaria :
Culex : …………………
Answer:
Elephantiasis

3. Housefly : Typhoid : : Dog : ………….
Answer:
Rabies

4. Decrease in blood platelets : :
Dengue : : Difficulty in breathing : ……………
Answer:
Swine flu

5. Cancer : Laparoscopic surgery : :
Heart disease :……………
Answer:
By-Pass surgery.

Distinguish between the following:

Question 1.
Typhoid and Tuberculosis :
Answer:

What can be achieved/can be prevented?/Give reasons.

Question 1.
People suffering from communicable diseases should avoid going to public places.
Answer:

1. Communicable diseases spread when people share space with a diseased person.
2. If people suffering from l communicable diseases go to a public place, they would spread the disease causing germs in the air.
3. These germs can be transmitted to other healthy persons.
4. If the resistance power of the persons is less, they will fall sick by getting infected.
5. This may break into an epidemic. Therefore, people suffering from communicable diseases should avoid going to public places.

Question 2.
Pet animals should be given anti-rabies vaccine.
Answer:

1. We keep animals like cats and dogs at home as pets.
2. They may get infected with the virus of rabies.
3. If such an infected pet bites us, we may also get rabies.
4. Rabies is a lethal disease.
5. In order to protect the animals and to prevent rabies being transmitted, they should be given anti-rabies vaccine.

Question 3.
Tuberculosis is considered as the most communicable disease.
Answer:

1. Tuberculosis is caused due to bacterial infection.
2. It is an air-borne infection and spreads through the spittle of T.B. patient.
3. When personal and public hygiene is not followed, this disease spreads very rapidly.
4. It is estimated that every two minutes, one patient dies of T.B. in India. Tuberculosis, therefore, is considered as the most communicable disease.

Question 4.
ORS gives temporary relief to the patient of diarrhoea.
Answer:

1. In diarrhoea, due to loose motions the patient becomes dehydrated.
2. The eyes get sunken and the mouth becomes dry.
3. If immediate help is not given, the condition can become critical. The absorption function of the intestine is disturbed.
4. But by giving ORS, enough water, sugar and salt enter the body saving the life of the patient.
5. The sugar and salt in the ORS gets absorbed in the intestine and reduce the dehydration.
6. However, for eradication of infection, proper medical treatment is to be given, therefore, ORS gives only a temporary relief to the patient of diarrhoea.

Answer the following questions in one sentence:

Question 1.
Which virus causes dengue and how does it spread?
Answer:
Dengue is caused by DEN-1, 2 virus belonging to the type – flavivirus. Aedes aegypti type of mosquito spreads the disease by transferring this virus through its bite.

Question 2.
What are the reasons for spread of swine flu?
Answer:
Swine flu is caused by the virus influenza A (H1N1). Its carrier is pig. The contact with such pigs or infected persons can cause infection of swine flu. The infection spreads through sweat and through secretions of nose, throat and saliva of the diseased person.

Question 3.
What are the symptoms of swine flu?
Answer:
Symptoms of swine flu : Palpitations, difficulty in breathing, sore throat, body pain along with high fever.

Question 4.
In whom was HIV first reported?
Answer:
HIV was first reported in an African species of monkeys

Question 5.
What is a malignant tumour?
Answer:
Due to uncontrolled cell division
there is a formation of lump of cancerous cells. If this lump is without the covering, then it is called malignant tumour.

Question 6.
How is efficiency of the heart reduced?
Answer:
When the blood circulation for the heart muscles is obstructed, it does not receive enough oxygen and nutrients. Due to this condition heart has to exert more and gets stressed resulting into loss of efficiency.

Question 7.
What are the different types of treatment for heart diseases?
Answer:
Angioplasty, By-Pass surgery, open heart surgery, installation of stents, installation of pacemaker, heart transplant are some of the treatment for heart diseases.

Question 8.
What is Pradhan Mantri Jan Aushadhi Yojana? When was it started?
Answer:
Government of India started the Pradhan Mantri Jan Aushadhi Yojana on 1st July 2015. Under this scheme people who are not able to afford best quality medicines are given generic medicines of the same quality at much reduced price.

Question 9.
When can eye donation be done? What is the advantage of eye donation?
Answer:
Anybody can donate eyes posthumously. Due to eye donation, some blind person can regain the sight.

Explain the importance:

Question 1.
Generic medicines.
Answer:
Generic medicines are also called general medicines. They are affordable for the common citizens of India. These medicines are manufactured and distributed without any patent. They are similar in quality and composition as the branded i medicines. The proportion of compounds in these medicines and its formula of preparation is readily available. Thus the money spent on the research is reduced. Therefore, generic medicines are much cheaper than the expensive branded medicines.

Question 2.
Blood donation.
Answer:
Blood donation is said to be the greatest donation that one can give. Blood donation can save someone’s life. By one unit blood of a single donor, three different patients can be saved. From such blood red blood cells, white blood cells and blood i platelets can be separated and given to different patients who are in need with corresponding component. Blood cannot be manufactured artificially and hence blood donation is the only way to collect blood. One healthy person can donate blood four r times in a year, thus saving 12 patients.

Question 3.
First Aid for Heart Disease.
Answer:
A person who is suffering from cardiac problems can get a heart attack suddenly. In such case, the patient should be given immediate and appropriate treatment to save his or her life. First and foremost one should call 108 for cardiac ambulance. Then the patient’s pulse or heartbeats should be checked to know his/her condition. Check the consciousness of the patient. Then make the patient to lie on a hard surface in horizontal position.

Perform C.O.L.S. or, ‘Compression Only Life Support’ on the patient. During this procedure, a pressure is given in the centre of the thorax of a patient for at least 30 times at the rate of 100 to 120 r strokes per minute. This is a first aid for the r heart attack. Before the arrival of doctor or proper medical aid, the life of a patient is saved.

Answer the following questions:

Question 1.
Write a brief account about tuberculosis.
Answer:
Mycobacterium tuberculae is the bacteria which causes tuberculosis (TB) infection. This infectious and communicable disease passes through spittle of the patient. The sneezing and coughing of patient cause f droplet infections. With prolonged contact with the patient and using the objects of the patient there is greater chance of acquiring TB infection. Different body organs such as bones, uterus and lungs can be affected by tuberculosis.

The pulmonary TB i.e. TB of the lungs is more common. The symptoms of TB are prolonged cough, blood through spittle, decrease in the body weight and difficulty in breathing. B.C.G. vaccine can be given in young age for prevention of TB. The patient needs to be isolated if TB is detected. Regular antibiotics have to be taken. DOTS process of medication needs to be followed.

Question 2.
Write the symptoms of dengue.
Answer:
Symptoms of dengue are as follows:

1. High and severe fever.
2. Severe headache accompanied with vomiting.
3. Pain in the eye sockets as if someone is pushing the eyes out.
4. Rapid reduction in the number of blood platelets.
5. Internal haemorrhages in the body.

Question 3.
How is rabies caused? What are the important symptoms of the rabies?
Answer:
Rabies is a viral disease. The bite of a rabid animal (the animal who is already infected with rabies virus) transfers the virus in the human blood through the bite wound. Dog, rabbit, monkey and cat can be infected with rabies if they are not vaccinated. The virus of rabies enters the brain through neurons. If not treated in time, rabies can be fatal.

Symptoms of rabies: There is a fever which lasts for 2 to 12 weeks. The victim becomes hyper-excited. He /She shows exaggerations in behaviour. Hydrophobia is very unique symptom in which person is scared and phobic of water. The symptoms can be seen within 90 to 175 days after the animal-bite.
When the dog or any animal bites, before the symptoms are seen, the victim should immediately take anti-rabies vaccine. This vaccination can save a person.

Question 4.
What are the causes of cancer?
Answer:
The carcinogenic substances can cause cancer. Thus such substances should never be used. Tobacco, gutkha and other nicotine containing products can cause cancer. Smoking and alcoholism can also induce cancer development. Cancer is also hereditary disease which is said to be caused by oncogenes. The lack of high fibre food in the diet and junk food in great quantities can induce the cancer development in some part of the alimentary canal.

Question 5.
Write the symptoms of cancer.
Answer:

1. If part of the respiratory system is under the attack of cancer, it can cause, long term cough, hoarse voice, difficulty in swallowing or difficulty in breathing.
2. The wounds do not become cured and the scar too is incurable. Inflammations does not subside.
3. There is formation of tumour like lump in the breast of the females.
4. In all the types of cancer there is unexplained weight loss.

Question 6.
What are the preventive measures to avoid the cancer?
Answer:
Complete control over diet should be followed. It should be’ healthy and nutritive. Such diet protects one from the cancer. The modern treatment processes should be immediately carried out, if the cancer is detected. With time-lapse, the growth of the cancer keeps on increasing. Physical exercises should be regularly done. Tobacco consumption, smoking are some addictions that can induce cancer. These should never be tried.

Question 7.
What are the causes and symptoms of diabetes?
Answer:
Causes of diabetes: The pancreas in normal persons secrete hormone insulin which maintains the sugar level in the blood. When there is deficiency of insulin, the symptoms of diabetes develop due to uncontrolled blood sugar level. Hereditary causes also can develop diabetes.

Obesity, lack of physical exercise, mental stress can also lead to diabetes. Overconsumption of fried food and over-indulgence in eating sweetmeats increase the chances of diabetes.

Symptoms of diabetes: The person who develops diabetes has frequent urination and continuous thirst. The body weight also reduces rapidly. Sometimes it may rise suddenly. There is continuous feeling of fatigue.

Question 8.
What are the causes of heart diseases?
Answer:
Addictions such as smoking, alcoholism and junk food lead to heart disease. Diabetes, hypertension, obesity are responsible for developing heart disease. Lack of physical exercise, no physical work, continuous sedentary mode are some causes which reduce the efficiency of the working of heart. Mental strain and stress, anger, frustration, anxiety are some psychological reasons that can lead to heart problems

Question 9.
What happens when medicines are missed?
Answer:
When medicines are taken without the consultation of doctor, there are certain problems. When the medicines and drugs are taken without any cause or symptom, then it is a misuse. Overdose of pain killers produce side effects. Some of these cause damage to nervous system, excretory system and liver. Overdose of antibiotics develops nausea, stomachache, loose motions and rash, white patches on tongue, etc.

Questions based on charts/tables:

Question 1.
Complete the table: Prepare similar table of information as the table given on page 7 about various disease like enteritis, malaria, plague and leprosy.
Answer:

Question 2.
Draw a flow diagram to show treatment for heart diseases.
Answer:

Activity-based questions:

Question 1.
Enlist the names and composition of the medicines present at your home.
Answer:
Students are expected to write this answer based on the medicines in their own homes.

Question 2.
Observe and discuss :

Answer:
Observe the following pictures and write description in the boxes.

Open-Ended Questions:

Question 1.
Poor people do not afford the costly medicines. Is there any alternative for this? Which one?

Answer:
Some medicines are very costly. The poor people cannot afford such expensive medicines. In such cases, some social organizations may give some help to these patients. Some trusts like Tata trust can also offer help to the needy for the treatment.

Some hospitals have social workers who help the needy for raising the funds for poor patients. Another way is to use generic medicines.

These medicines are at par in quality with the branded medicines but they are quite less in the price. They are available in the generic medicine shops. One can also take benefit of Pradhan Mantri Jan Aushadhi Yojana.

Question 2.
What measures will you take to stop the breeding of mosquitoes?
Answer:
We have to take care that there is no water stagnated in and around the house. The garden plants and pots in the house should be checked for the mosquito larvae and eggs if any. If water is not receding and remaining accumulated, then the spraying of insecticides should be done with the help of elders. With the help of elders in the house, the complaint can be lodged in the Malaria eradication department in the nearby Municipality or Gram Panachyat office.

If the water is in ponds, we can release guppy fishes to eradicate the mosquito larvae. The fish feed on the larvae and automatically control the mosquito population.

Question 3.
Our behaviour with HIV infected person must be normal or should not be normal? What is your opinion? Write it with correct explanation.
Answer:
Our behaviour with HIV infected person must be normal. There are no chances of acquiring AIDS by having normal behaviour with the HIV positive person. HIV can pass only through body fluids and blood from HIV infected person to the other normal person. Similarly, the needles or syringes used by HIV infected person can cause the infection of HIV to the other person.

Such ways of contamination should always be avoided. The sexual contact or the blood transfusion with HIV positive person should always be avoided. But the normal behaviour such as hand-shake, eating together, studying in the same class will not matter at all in the transmission of AIDS.

Balbharati Maharashtra State Board 8th Std Science Textbook Solutions 

• Living World and Classification of Microbes Class 8 Science Textbook Solutions
• Health and Diseases Class 8 Science Textbook Solutions
• Force and Pressure Class 8 Science Textbook Solutions
• Current Electricity and Magnetism Class 8 Science Textbook Solutions
• Inside the Atom Class 8 Science Textbook Solutions
• Composition of Matter Class 8 Science Textbook Solutions
• Metals and Nonmetals Class 8 Science Textbook Solutions
• Pollution Class 8 Science Textbook Solutions
• Disaster Management Class 8 Science Textbook Solutions
• Cell and Cell Organelles Class 8 Science Textbook Solutions

Std 7 Science Chapter 10 Disaster Management Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 10 Disaster Management Notes, Textbook Exercise Important Questions and Answers.

Class 7 Science Chapter 10 Disaster Management Question Answer Maharashtra Board

1. Find the odd man out:

Question a.
Famine, earthquake, cloudburst, railway accident.
Answer:
Railway accident.

Question b.
Drought, heavy rains/storm, tsunami.
Answer:
Drought.

Question c.
Lava, hot mud, ash, locusts.
Answer:
Locusts.

Question d.
Washing away of crops, attack of pests on crops, volcano, singeing of crops.
Answer:
Volcano.

2. What are the remedial measures for the following calamities?

Question a.
Famine:
Answer:
Following are the remedial measures for famine:

1. Supply food and water to the people those who are dying due to hunger.
2. Give medicines to the people those who are suffering from malnutrition.
3. Government should start helping centres for the people those who are suffering from famine.
4. Give them temporary shelter in some other places where water and food are available.
5. Shift the animals to safer places.
6. Do proper planning so that region doesn’t get famine again and again.
7. Reuse water
8. grow more trees.

Question b.
Lightning strike:
Answer:
Following are the remedial measures for lightning strike:

1. Give immediate treatment to the lightning affected persons so their life can be saved.
2. Keep the people away from the open ground and swimming pool.
3. Provide them proper guidelines to cure for the lightning strike.

Question c.
Storm:
Answer:

1. Supply food, water and medicines to the people
2. Shift them to safe places.
3. Maintain peace, and advice the people not to panic.
4. Give time to time report on T.V. and radio.

Question d.
Cloudburst:
Answer:
Following are the remedial measures for cloudburst:

1. Shift people to safe places with the help of airplane, helicopter and army.
2. Supply them food, clothes, water and medicines.
3. Give time to time weather report.
4. Open more helpline centres.
5. Government should immediately send the help in terms of money and army to the people.

3. True or false? Give reasons for your answer.

Question a.
Information about a forthcoming storm is to be kept secret.
Answer:
False. Information about a forthcoming storm is not to be kept secret because, with this information we can take immediate steps for disaster management. Large scale damage of property and loss of life can be avoided.

Question b.
You should not swim when there is lightning in the sky.
Answer:
True. Lightning carries some electric charges which causes electric current in it. Water catches this current so if any person is swimming pool during lightning in the sky, then there are more chances that lightning may strike in water and the person may die due to it.

Question c.
It is possible to prevent the eruption of a volcano.
Answer:
False. It is not possible to prevent the eruption of a volcano because it is a natural event. However, by means of science and technology, it is possible to predict an eruption in advance and to take immediate steps for disaster management.

Question d.
Heavy rains result in famine.
Answer:
True. Heavy rains result in flood so crops get washed away or damaged in the flood and results in famine.

Question e.
A loud crashing sound follows a lightning.
Answer:
True, Friction and brushing happens between two clouds making them charged and lightning is produced between two clouds or one cloud and earth. The temperature increases and air pressure also increases to high amount and produces a loud sound of thunder.

4. Write answers to the following questions in our own words.

Question a.
What is a tsunami? What gives rise to a tsunami?
Answer:

1. Waves generated by an earthquake or volcano occurring on the ocean floor is called ‘tsunami’. ‘Tsunami’ is a Japanese word which means ‘harbour wave’.
2. As on land, earthquakes and volcanic eruptions occur, at the bottom of the sea, too.
3. If an earthquake occurs at the bottom of ocean, the energy released pushes the water upwards. As a result of this particular type of waves are formed.
4. These waves are not very high near the source, but they start spreading very fast to long distances.
5. The velocity of these waves is 800 to 900 km/hr. When they reach a coastal area, their velocity is reduced, but their height is found to have increased tremendously even to about 30 m. These are tsunami waves.

Question b.
What is cloudburst?
Answer:

1. Sometimes the water coming down from rain clouds does not reach the land in the form of rain. Instead, due to very high temperature near the land, it vaporizes and goes back into the same clouds.
2. As a result the amount of vapour in those clouds becomes very high.
3. Due to rapid condensation, it rains suddenly over a specific and small region at a rate of 100 mm per hour or more. This is known as a cloudburst.

Question c.
Explain the effects of a volcano.
Answer:
Following are the effects of a volcano:

1. The chemical substances such as lava, vapour, hot mud, sulphur etc. get collected on the surface of the earth and thereby mountains and hills are created
2. The atmosphere gets polluted due to the ash and gases ejected by the volcano.
3. Often, it rains as a result of a volcanic eruption.
4. The temperature rises due to hot gases.
5. Forests and settlement get buried under the hot mud.

Question d.
What are the measures to prevent loss of life due to lightning?
Answer:
Following are the measures to prevent loss of life due to lightning:

1. Do not stand on open ground, below a tree, on high location, near an electric pole, near a telephone pole or a tower etc.
2. Do not lean on wire fences around a farm, a compound, a garden or a house.
3. If you are on two-wheeler, a bicycle, a tractor or a boat, get off immediately and go to safe place.
4. Do not gather all together in one place.
5. Take care to keep a distance of 15 feet between any two persons.
6. Do not use plugged in electrical appliances. Do not use a mobile or telephone.
7. Stand on dry wood, a plastic sheet, sack or jute cloth or dry leaves.
8. Keeping your feet together support yourself on the soles of your feet placing your hands on your knees and crouch low.
9. Swimmers and fishermen should immediately come out of the water.
10. A pucca house is the safest place. Find out if there is a lightning conductor on any tall building near your house. If necessary get a lightning conductor fitted on your house.

5. What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?

Question a.
What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?
Answer:
In Maharashtra, all districts have their own disaster management plan to deal with calamities such as floods and landslides.

1. The plan deals extensively with the emergency, and evacuation measures to be taken up in cases of flood and landslide.
2. The district-level disaster management plan has detailed information about geographical details, population, flood-prone areas, villages and other macro details.
3. Nearly 14 such key departments are engaged in disaster mitigation measures and each one has been assigned a specific task to do at times of natural disasters.
4. The administration is now training master trainers at the district level who in turn will train key persons at village and taluka levels to deal with a natural disaster.
5. The administration through radio jingles, public advertisements and other measures is informing people about how to react at times of flood and landslide.
6. Currently, the Indian Meteorological Department (IMD) gives weather forecast on daily basis and for the next 5 days with advice to farmers on when to start crop sowing and harvesting etc.

6. With reference to disaster management what are the things in your house that you will check?

Question a.
With reference to disaster management what are the things in your house that you will check?
Answer:
With reference to disaster management, we should keep the following things at home and check regularly.

1. Keep proper first aid kit at a handy place.
2. Keep all the electric connections in proper condition.
3. Keep the gas line or tube connection proper.
4. Keep self-powered flashlights and self-powered radios.
5. Keep non-perishable food which will last for a week.
6. Keep a fire extinguisher handy and in proper condition.
7. Keep updated telephone diary which should have emergency phone numbers.

Project:

Question 1.
With the help of the Internet, collect information about the places where a calamity has occurred.

Question 2.
Collect information from the Internet about how cyclonic storms are named.

Class 7 Science Chapter 10 Disaster Management Important Questions and Answers

Fill in the blanks:

Question 1.
………… and ………… disasters are related to each other.
Answer:
Natural manmade.

Question 2.
………… implemented a canal scheme for drinking water in Aurangabad.
Answer:
Malik Ambar.

Question 3.
………… has turned out to be the most famine-affected contents of the world.
Answer:
Asia

Question 4.
The government of India established the ………… in 1976.
Answer:
National Flood Commission

Question 5.
The ………… that occurred in Mumbai on 26th August 2005 was extraordinary and unforgettable.
Answer:
cloudburst.

Question 6.
A cloudburst occurred at ………… on 6th August, 2010.
Answer:
Ladakh (Leh)

Question 7.
About ………… lightning flashes occur per second in the atmosphere.
Answer:
40.

Question 8.
The temperature generated by ………… is higher than that of the sun.
Answer:
lightning

Question 9.
When some substances comes out of the earth’s crust in an eruption and start flowing is called a ………… .
Answer:
volcano

Question 10.
Some islands are created due to the eruption, of ………… in the sea.
Answer:
volcano

Question 11.
………… is a Japanese word which means ‘harbour wave’.
Answer:
Tsunami.

Question 12.
About ………… nations from all over the world are members of the UNDP.
Answer:
177.

Question 13.
………… established a standing international organization UNDP in 1965.
Answer:
United Nations.

Question 14.
………… is celebrated as International Day for Disaster Reduction.
Answer:
13th October

Question 15.
The condition that arises due to long term and severe scarcity of food grains and water is called………. .
Answer:
famine

Can you tell?

Question 1.
Is it possible to prevent the loss of life caused by lightning?
Answer:
Yes, it is possible to prevent the loss of life caused by lightning, by taking precautions.

Question 2.
What should be done to prevent the bunds on a farm from getting washed away in the rainy season?
Answer:

1. Grow more trees near the bunds.
2. Grow grass strips.
3. Make stone lines near the bunds.
4. Use contour ploughing and tillage network method to prevent the bunds on a farm from getting washed away in the rainy season.

Question 3.
Why do we experience water scarcity?
Answer:
Lessor no rain leads to water scarcity.

Question 4.
What causes rain?
Answer:

1. Due to heat of the sun, water from the sea, lake and river gets evaporated and this water vapour is light in weight so it goes higher and higher and forms the cloud.
2. At a certain level the amount of vapour in those clouds becomes very heavy and it burst and rain occurs.

Question 5.
Have you seen a flash of lightning in the sky? When?
Answer:
Students will answer this question based on their experience.

Question 6.
What causes lightning?
Answer:

1. Where air and clouds rub against each other in the sky, the upper part of some clouds on the upper side becomes positively charged and the lower sides become negatively charged.
2. When this negative charge on the bottom of the cloud becomes much larger than the charge on the ground it starts flowing towards the ground in stages.
3. This happens very fast, in much less than a second and heat, light and sound energy are produced along with the electric current.

Use your brainpower!

Answer the following questions:

Question 1.
We should not wait at the foothill while it is raining heavily.
Answer:
During heavy rain there are chances of landslide and flood, so we should not wait at the foothill while it is raining heavily.

Maharashtra State Board Class 7 Science Textbook Solutions

• The Living World: Adaptations and Classification Class 7 Science Textbook Solutions
• Plants: Structure and Function Class 7 Science Textbook Solutions
• Properties of Natural Resources Class 7 Science Textbook Solutions
• Nutrition in Living Organisms Class 7 Science Textbook Solutions
• Food Safety Class 7 Science Textbook Solutions
• Measurement of Physical Quantities Class 7 Science Textbook Solutions
• Motion, Force and Work Class 7 Science Textbook Solutions
• Static Electricity Class 7 Science Textbook Solutions
• Heat Class 7 Science Textbook Solutions
• Disaster Management Class 7 Science Textbook Solutions

Std 6 Science Chapter 12 Simple Machines Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 6 Science Solutions Chapter 12 Simple Machines Notes, Textbook Exercise Important Questions and Answers.

Class 6 Science Chapter 12 Simple Machines Question Answer Maharashtra Board

1. Classify the following as a lever, a pulley and an inclined plane:
(A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife)

Question a.
Classify the following as a lever, a pulley and an inclined plane:
(A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife)
Answer:

2. Fill in the blanks using the proper word and complete the statements.

Question a.
The ………….. in the centre, the ………….. on one side and the on the ………….. other side make a lever of the first order.
Answer:
Fulcrum, load and effort

Question b.
The ………….. in the centre, the ………….. on one side and the ………….. on the other side make a lever of the second order.
Answer:
Load, fulcrum, effort

Question c.
The ………….. in the centre, the ………….. on one side and the ………….. on the other side make a lever of the third order.
Answer:
Effort, fulcrum, load

3. Which machines will you use to do the following work? Write their types.

Question a.
To remove the lid of a tin. Opener Lever of the second order
Answer:

• Work: To remove the lid of a tin.
• Machine: Opener
• Machine: Lever of the second order

Question b.
To lift bricks to the top of a tall building Crane Complex machine
Answer:

• Work: To lift bricks to the top of a tall building
• Machine: Crane
• Machine: Complex machine

Question c.
To cut vegetable Knife Wedge – Simple machine
Answer:

• Work: To cut vegetable
• Machine: Knife
• Machine: Wedge – Simple machine

Question d.
To draw water from a well Pulley Simple machine
Answer:

• Work: To draw water from a well
• Machine: Pulley
• Machine: Simple machine

Question e.
To hold a papad for roasting it. A pair of tongs Lever of the third order
Answer:

• Work: To hold a papad for roasting it.
• Machine: A pair of tongs
• Machine: Lever of the third order

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

Question a.
What is meant by a simple machine?
Answer:

1. Machines which have only one or two parts and a simple and easy structure are simple machines.
2. Example: the bottle opener, nail cutter.
3. Simple machines can be handled easily.
4. We use many simple machines in our day to day life.

Question b.
Mention the advantages of using a machine.
Answer:

1. Machines, simple or complex, are used to get more work done in less time and with less effort.
2. Machines are used to accomplish certain tasks more easily.
3. Use of simple or complex machines depends upon the task to be carried out and the time and the efforts required to do it.

Question c.
What is meant by a complex machine?
Answer:

1. Complex machines have many parts which carry out many processes for completing a task.
2. For this purpose the parts are joined to one another.
3. Therefore, these machines are called complex machines.
4. Some of the parts of such complex machines are actually simple machines.
5. The structure of complex machine is complicated.

Question d.
What is a lever? How is the order of the lever determined?
Answer:

1. Lever is a simple machine made up of 3 parts: Load, effort and fulcrum.
2. Order of the lever are determined on the position of the effort, the fulcrum and the load.

5. Why is this so?

Question a.
Traveller’s bags have wheels.
Answer:

1. Combination of wheel and axle is a simple machine.
2. When the axle starts rotating due to force applied, the wheel fitted to it also starts rotating.
3. This makes easier for travellers to carry heavy load.
4. Instead of lifting heavy bag, to drawing it on wheels require less energy. Therefore, traveller’s bag have wheels.

Question b.
Machines have to be maintained.
Answer:

1. Parts of machines rub against one another when they are used.
2. Soiled, dusty parts create more friction. Some parts are affected by the weather, rust and corrosion.
3. Machines get damaged or become useless due to such wear and tear. Hence to avoid this, machines should be maintained properly to keep them in good working condition.

Question c.
A bicycle is said to be a complex machine.
Answer:

1. Bicycle has a complicated structure.
2. Bicycle has many parts which carry out many processes for completing a task.
3. Many parts of bicycle such as pedals, wheels, axle, handle are actually simple machines.
4. The parts of a bicycle are joined to one another – making it a complex machine.

6. Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs.

Question a.
Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs.
Answer:
Levers:

1. See – saw – lever of the first order.
   Load – fulcrum – effort.
2. Wheelbarrow – lever of the second order.
   Fulcrum – load – effort.
3. Lemon squeezers – lever of the second order.
   Fulcrum – load – effort.
4. Tongs – lever of the third order.
   Fulcrum – effort – load.

Activity:

Question 1.
Make a list of the various machines used in your home and neighborhood and write their types.

Question 2.
Go to a bicycle repair shop, observe how a bicycle is repaired, and note down the information.

Class 6 Science Chapter 12 Simple Machines Important Questions and Answers

Fill in the blanks.

Question 1.
Simple machines can be handled ………….. .
Answer:
easily

Question 2.
The structure of complex machine is ………….. .
Answer:
complicated

Question 3.
The more gradual the the ………….. lesser is the we bear. But, such an inclined plane is ………….. .
Answer:
slope, weight, longer

Question 4.
The steeper the ………….. , the ………….. is the inclined plane. But we have to bear a …………. weight.
Answer:
slope, shorter, greater

Question 5.
A screw is like a rolled up inclined plane made of an ………….. strip.
Answer:
iron

Question 6.
A wedge is used for ………… an object into two pieces or to ………….. the objects stuck together.
Answer:
breaking, separate

Question 7.
A farmer uses a strong …………. to remove the big stone bogged down in the farm.
Answer:
crow-bar

Question 8.
A device with a grooved wheel and thread designed to lift weights is called a …………. .
Answer:
pulley

Question 9.
When we use a pulley, force is applied in the downward direction for lifting the weight in an …………. direction.
Answer:
upward

Question 10.
Combination of an axle and a wheel is a …………. machine.
Answer:
simple

Question 11.
A needle and a nail are also kind of …………. .
Answer:
wedge

Question 12.
Machines are covered when not in use to prevent …………. settling on them.
Answer:
dust

Question 13.
In Archimedes’ screw, the pipe was placed at an angle of …………. with one end inside the …………. and the rod resting on a …………. .
Answer:
45°, water, flat surface.

Match the columns:

Question 1.

Answer:

Question 2.

Answer:

State whether the following statements are ‘true’ or ‘false’.

Question 1.
Lever helps big vehicle to climb up and down the mountain easily.
Answer:
False

Question 2.
Combination of wheel and axle is a simple machine.
Answer:
True

Question 3.
In pulley, force can be applied in upward direction.
Answer:
False

Question 4.
Screw is an example of wedge.
Answer:
False

Question 5.
In Archimedes screw, the rod rests on flat surface.
Answer:
True

Question 6.
A slanting plank is used to lift a weight.
Answer:
True

Question 7.
A winding road or ghat is an example of lever of first order.
Answer:
False

Answer the following questions in one sentence.

Question 1.
What is a machine?
Answer:
Devices which are used to get more work done in less time and less effort are called machines.

Question 2.
What is a simple machine?
Answer:
Machines which have only one or two parts and a simple and easy structure are called simple machines.

Question 3.
What is a complex machine?
Answer:
Some machines have many parts and they carry out many processes for completing a task. For this purpose, the parts are joined to each other. They are called complex machines.

Question 4.
List the properties of simple machines.
Answer:
Properties of simple machine are:

1. They are made up of only one or two parts.
2. They have a simple and easy structure.
3. They can be handled easily.
4. There are less chances of simple machines breaking down or getting damaged.

Question 5.
List properties of complex machines.
Answer:
Properties of complex machine are:

1. These machines have many parts to carry out many processes.
2. The parts are joined to one another.
3. The structure of complex machines is complicated.
4. Some parts of complex machines are actually simple machines.

Question 6.
What is an inclined plane?
Answer:
A slanting plank which is used to lift a weight on which we bear less weight and lifting becomes easier is an inclined plane.

Question 7.
What is a screw?
Answer:
A screw is like a rolled up inclined plane made up of iron strip.

Question 8.
What is a wedge?
Answer:
A wedge is used for breaking an object into two pieces or to separate objects stuck together.

Question 9.
State examples of wedges.
Answer:
An axle, a knife, a chisel, a needle and a nail are different kinds of wedges.

Question 10.
What is a lever?
Answer:
A lever is a machine made up of 3 parts: effort, load and fulcrum.

Question 11.
What is a fulcrum?
Answer:
The support at which the rod of a lever is rested is called fulcrum of a lever. The lever rotates about the fulcrum.

Question 12.
What is a load?
Answer:
The weight lifted by a lever or the force against which the lever acts is called a load.

Question 13.
What is a load arm?
Answer:
The arm of the lever from the fulcrum to the load is called a load arm.

Question 14.
What is an effort?
Answer:
The force applied on the other end of the rod to lift the load is called an effort.

Question 15.
What is an effort arm?
Answer:
The part of the lever from the fulcrum to the effort is called an effort arm.

Question 16.
What is lever of the first order?
Answer:
The fulcrum is in the centre, the load is at one end while effort is at other end.

Question 17.
What is lever of the second order?
Answer:
The load is in the centre, the fulcrum on one side, and the effort on the other side.

Question 18.
What is lever of the third order?
Answer:
The effort is in the centre, the fulcrum on one side, and the load on the other side.

Question 19.
What is a pulley?
Answer:
A pulley is a device with a grooved wheel and thread designed to lift weights.

Question 2.
How does a pulley help us?
Answer:
If we use a pulley, force can be applied in the downward direction for lifting the weight in an upward direction. It is convenient and easy.

Give scientific reasons:

Question 1.
We use many simple machines in our day-to-day life.
Answer:
Simple machines can be handled easily and there are less chances of these machines breaking down or getting damaged. Hence, we use many simple machines in our day-to-day life.

Question 2.
Less force is required to fit a screw than to hammer a nail.
Answer:

1. A screw is like a rolled-up inclined plane of an iron strip.
2. When a screw is fitted in wood it goes in as if it is going down an inclined plane.
3. Therefore, less force is required to fit a screw than hammer a nail.

Question 3.
Big vehicles easily climb up and down the mountains than a pathway.
Answer:
A winding road or ghat that goes up a mountain is like an inclined plane wrapped around the mountain. It helps big vehicles to climb, up and down the mountain easily.

Question 4.
Oil or lubricant is released between parts of machine.
Answer:
Oil or lubricant is released between parts that rub against each other so that there is less friction between them and wearing is reduced.

Question 5.
Machines are covered when not in use.
Answer:
Machines are covered when not in use to prevent dust settling on them.

Question 6.
How are machines protected from the effect of weather?
Answer:
To prevent the effect of weather, metallic parts in a machine are painted externally and the machines are always kept dry.

Draw the neat and labelled diagram of following:

Question 1.
The screw as an inclined plane.
Answer:

Question 2.
Archimedes’ screw
Answer:

Observe the following diagram and identify the order of lever.

Question 1.
Removing the lid.
Answer:

Question 2.
Picking up an object.
Answer:

Question 3.
Lifting a paper weight.

Answer:

1. Lever of the second order
2. lever of third order
3. Level of first order.

Answer each of the question in brief:

Question 1.
With the help of the diagram explain lever of the 1st, 2nd, 3rd order.
Answer:
1. Lever of the First order: The fulcrum is in the centre, the load is at one end, while the effort is at the other end. e.g. scissors

2. Lever of the Second order: The load is in the centre, the fulcrum on one side, and the effort on the other side. e.g. lid opener

3. Lever of the Third order: The effort is in the centre, the fulcrum on one side, and the load on the other side. e.g. Tongs

Question 2.
How can machines be maintained?
Answer:

1. To maintain machines, all its parts are wiped clean.
2. Oil or lubricant is released between parts that rub against each other.
3. Machines are covered, painted externally and always kept dry.

Question 3.
What is an inclined plane? Explain longer and shorter inclined plane.
Answer:

1. A slanting plank used to lift a weight, is called an inclined plane. Because of inclined plane we will experience less weight and weight lifting become easier.
2. Longer inclined plane: When the inclined plane is longer, the slope is more gradual and lesser is the weight we bear.
3. Shorter inclined plane: When the inclined plane is shorter, the slope is steeper and greater is the weight we bear.

Question 6.
Explain the working of a giant wheel.
Answer:

1. The giant wheel is fitted to a rod at its centre. This rod is called an axle.
2. When the axle starts rotating with the help of electricity the wheel fitted to it starts rotating.
3. This combination of an axle and a wheel is a simple machine.

Observe and discuss:

Question 1.
Name the devices and discuss how they help.

Answer:

1. Needle and thread – Stitching of clothes
2. Wheelbarrow – To carry materials.
3. Opener – To open the lids of bottles.
4. Pulley – To lift bucket
5. Nail cutter – To cut nails
6. Axe – To cut wood into small pieces

Can you tell?

Question 1.
Observe the machines shown in the following pictures. For what purposes are they used? Can you name some other machines of this kind?

Answer:

1. Mixer grinder – To grind the foodstuffs
2. Scooter – To ride and reach places
3. Bicycle – To ride and reach places
4. Sewing machine – To stitch clothes
5. Wheel chair – Specially designed for handicapped patients to move around.

Question 2.
Compare the pathway and a road, available to climb the mountain, the time and strength and your convenience, required to reach the mountain top.
Answer:
We can reach the mountain top by climbing the pathway early than by the road. The time required is less but the strength required is more. The road is easy to walk and more time consuming.

Question 3.
If the point of a needle or the edge of a knife become blunt, then the needle does not penetrate the cloth and the knife does not cut into the fruit. Why is this so?
Answer:
The tip of the needle or the edge of a knife becomes blunt due to regular use. Both the knife and the needle lose their sharpness.

Use your brain power!

Question 1.
Which task can be done using a lever?
Answer:
Task such as using a nut cracker, cutting paper with scissors, can be done using a lever.

Question 2.
Some machines we use in our day to day life are shown in picture. What is the type in each of these?

Answer:

• Wheelbarrow – Lever of the third order
• Pair of tongs – Lever of the first order
• See – saw – Lever of the first
• order Cutter – Lever of the second lever
• Pair of Scissors – Lever of the first order.

Question 3.
When the pedal of the bicycle is rotating, the wheel starts rotating. How does this happen?
Answer:
Pedals of the bicycle are connected to the wheels through the axle, when the axle starts rotating, the wheels also start rotating.

Question 4.
Examples of pulley.
Answer:

1. A simple pulley is used to hoist a flag, to draw water from a well.
2. The crane which is used to lift heavy loads is an example of application of pulleys and levers working together.

Maharashtra State Board Class 6 Science Textbook Solutions

• Work and Energy Class 6 Science Textbook Solutions
• Simple Machines Class 6 Science Textbook Solutions
• Sound Class 6 Science Textbook Solutions
• Light and the Formation of Shadows Class 6 Science Textbook Solutions
• Fun with Magnets Class 6 Science Textbook Solutions
• The Universe Class 6 Science Textbook Solutions

Std 6 Science Chapter 3 Diversity in Living Things and their Classification Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 6 Science Solutions Chapter 3 Diversity in Living Things and their Classification Notes, Textbook Exercise Important Questions and Answers.

Class 6 Science Chapter 3 Diversity in Living Things and their Classification Question Answer Maharashtra Board

1. Match the pairs.

diversity in living things and their classification class 6 exercise Question 1.

Answer:

2. Who is the odd one out?

Question a.
Fungus, mushroom, chrysanthemum, spirogyra
Answer:
Chrysanthemum (only flowering plants)
or
Spirogyra (only aquatic plant)

Question b.
Mango, banyan, palm, chickpea
Answer:
Chickpea (shrub, others are not)
or
Palm (tall tree without any branches, others have branches)

Question c.
Grape, orange, lemon, hibiscus
Answer:
Grape (only creeper, others are not)
or
Hibiscus (flower, others are fruits)

Question d.
Sunflower, banyan, jowar, bajra
Answer:
Banyan (perinnial, others are not)

Question e.
Guava, radish, carrot, beetroot
Answer:
Gauva (fruit, others are roots)

Question f.
Deer, fish, man, worms
Answer:
Worms (invertebrate, others are not)
or
Fish (aquatic animal, others are terristrial animals

3. What is the difference?

Question a.
Flowering plant and Non-flowering plant
Answer:

Question b.
A Tree and a Shrub
Answer:

Question c.
Vertebrates and Invertebrates
Answer:

4. True or false?

Question a.
The snail is an aquatic animal.
Answer:
False

Question b.
Amphibians can live in air and in water.
Answer:
False

Question c.
The function of the brain is well developed in vertebrate.
Answer:
True

Question d.
The amoeba is a multicellular animal.
Answer:
False

5. Write two names of each. 

Question a.
A flowering plant
Answer:
Rose, hibiscus

Question b.
A non-flowering plant
Answer:
Fern, algae

Question c.
A tree
Answer:
Mango, banyan

Question d.
A shrub
Answer:
Oleander, hibiscus

Question e.
A creeper
Answer:
Pumpkin, watermelon

Question f.
An annual plant
Answer:
Jowar, sunflower

Question g.
A biennial plant
Answer:
Carrot, beetroot

Question h.
A perennial plant
Answer:
Mango, gulmohar

6. Write answers to the following. 

Question a.
What are the parts of a plant?
Answer:
The parts of a plant are: root, stem, leaves, flowers, fruit and seed.

Question b.
What are the functions of root?
Answer:
The functions of root are:

1. The root hold the soil firmly and anchor the plant.
2. They absorb water, salt and minerals from the soil and transport it to stem.
3. Some roots store food. e.g. Carrot, radish.

Question c.
Why is it necessary to classify living things?
Answer:

1. There is a great diversity in living things- both plants and animals on the earth.
2. In order to identify them and to study their characteristics, systematic classification is necessary.

Question d.
What are the criteria used to classify living things?
Answer:
Following are the criteria used to classify living things:
a. Plants:

• Mode of nutrition.
• Similarities and differences in structure.
• Presence of flowers or not.
• Period of life cycles.
• Habitat.

b. Animals:

• Cell structure.
• Presence of vertebral column.
• Method of reproduction.
• Habitat.

Question e.
Tell some characteristics of creepers.
Answer:
The characteristics of creepers are:

1. The stem of a creeper is very flexible, soft and green and need support to climb.
2. Some climbers spread on the ground, e.g. Pumpkin
3. Some have aerial roots, e.g. Money plant
4. Some climbers develop tendrils, e.g. Cucumber

Question f.
Explain the characteristics of herbs with examples.
Answer:

1. Herbs grow 1 to 1.5 m tall.
2. Their stem is green and quite flexible.
3. They may live for a few months or upto two years, e.g. Tulsi, oregano, etc.

Question g.
How is the body of animals protected?
Answer:
Body of animals are protected by special covering such as skins, feathers, scales, hair fur, etc.

Question h.
On the basis of which criteria will you classify plants and animals?
Answer:

7. Draw figures. 

Question a.
Draw the figure of a plant to show the parts, namely, the root, stem and leaves in it.
Answer:

Activity:

Question 1.
Visit a plant nursery and classify the plants there.

Question 2.
Visit a zoo and obtain information about the diversity in animals.

Question 3.
Write an essay on diversity in plants.

Question 4.
Collect seeds of various plants during summer and throw them in open spaces (fallow land, moorland, hill, etc.) during the rainy season.

Class 6 Science Chapter 3 Diversity in Living Things and their Classification Important Questions and Answers

Fill in the blanks:

Question 1.
Plants that can prepare their own food are called ………….. plants.
Answer:
autotrophic

Question 2.
Pitcher plants are ………….. .
Answer:
insectivorous

Question 3.
The ………….. is an important means of reproduction.
Answer:
flower

Question 4.
Animals that lay eggs are ………….. animals.
Answer:
oviparous

Question 5.
Animals that can live on land as well as water are called ………….. .
Answer:
amphibians

Choose the correct alternative:

Question 1.
The ………….. is a perennial.
(a) beetroot
(b) gulmohar
(c) grass
Answer:
(b) gulmohar

Question 2.
The sunflower is a / an ………….. plant.
(a) annual
(b) biennial
(c) perennial
Answer:
(a) annual

Question 3.
Cactus is a ………….. plant.
(a) land
(b) water
(c) desert
Answer:
(c) desert

Question 4.
The …………….. is a unicellular animal.
(a) cockroach
(b) snail
(c) paramoecium
Answer:
(c) paramoecium

Question 5.
Hen is a …………….. animal.
(a) oviparous
(b) viviparous
(c) none of above
Answer:
(b) oviparous

Question 6.
Earthworm is a / an ……………. animal.
(a) vertebrate
(b) invertebrate
(c) unicellular
Answer:
(b) invertebrate

True or False:

Question 1.
The pods of beans and peas are actually fruits.
Answer:
True

Question 2.
Fungus is heterotrophic.
Answer:
True

Write two names of each.

Question 1.
An invertebrate animal
Answer:
Earthworm, cockroach

Question 2.
An oviparous animal.
Answer:
Hen, sparrow

Distinguish between:

Question 1.
Autotrophic plant and Heterotrophic plant
Answer:

Classify as directed.

Question 1.
Into annual, biennial, perennial
Sunflower, carrot, bajra, mango, jowar, oleander, beetroot, coconut
Answer:

Question 2.
Into vertebrates and invertebrates
Fish, cat, earthworm, snail, hen, cockroach
Answer:

Define. 

Class 6 Science Chapter 3 Diversity In Living Things and Their Classification Question 1.
Unicellular animal
Answer:
Animals which have a single cell body performing all functions, are called unicellular animals, e.g. Amoeba

Diversity In Living Things And Their Classification Exercise Question 2.
Multicellular animals
Answer:
Animals which have many cells in their body, are called multicellular animals, e.g. Cat

Diversity In Living Things and Their Classification Question 3.
Vertebrates
Answer:
Animals with vertebral column are called vertebrates, e.g. Man

Question 4.
Invertebrate animals
Answer:
Animals without vertebrate column are called invertebrate animals, e.g. Earthworm

Question 5.
Oviparous animals
Answer:
Animals which lay eggs and hatch them are called oviparous animals, e.g. Hen

Question 6.
Viviparous animals
Answer:
Animals which give birth to their young ones are called viviparous animals, e.g. Dog

Answer the following:

Question 1.
Give the functions of:
Answer:
a. Stem:
1. The stem gives support to the other parts of the plant.
2. The stem carries out the function of production, conduction and storage of the food.
3. In some cases it stores food.
b. Leaves: They play an important role in the production of food.
c. Flowers: The flowers are reproductive organ of plant.
d. Fruits: Fruits have seeds which give rise to new plant.
e. Seeds: From the seeds arise new plants.

Answer the following in short.

Question 1.
What type of plants are toolstools and mushrooms?
Answer:
Toolstools and mushrooms are heterotrophs.

Question 2.
What type of plant is a fig?
Answer:
Fig is a tree.

Question 3.
Do ferns, algae and money plant bear flowers?
Answer:
Ferns, algae and money plants do not bear flowers. They are non-flowering plants.

Question 4.
Which is the largest flower and where is it found?
Answer:
Rafflesia Arnoldi is the world’s largest flower. It is found in Indonesia.

Question 5.
Where does pomegranate grow?
Answer:
Pomegranate is a shrub which grows on land in soil.

Question 6.
Where do bulrushes and railroad creepers grow?
Answer:
Bulrushes is a water plant and railroad creepers grow along the ground.

Question 7.
Where does lotus grow?
Answer:
Lotus grows in water.

Question 8.
Where does the dodder plant grow?
Answer:
Dodder is a parasitic plant and grows on other plants.

Question 9.
Why does water hyacinth float?
Answer:
The stem of water hyacinth is filled with air and its leaves are specially modified, which helps it to float in water.

Question 10.
Why is the stem of a cactus plant fleshy?
Answer:
Cactus is a desert plant. As there is a shortage of water, cactus stores water in its stem and hence, stem of cactus is fleshy.

Question 11.
Which spheres of the earth do living things exist?
Answer:
Living things exists in all three spheres of earth, i.e. Atmosphere, lithosphere and hydrosphere.

Question 12.
Are the plants and animals that you have seen all alike?
Answer:
No. They are all of different types.

Question 13.
What are the similarities between a mango, a banyan and a tamarind tree?
Answer:
They are tall, big and perennial plants.

Question 14.
What are the similarities between the hibiscus, oleander and lantana plants?
Answer:
They are shorter and smaller than trees.

Question 15.
What are the similarities between fenugreek and periwinkle plants?
Answer:
They are smaller and shorter than trees and shrubs.

Question 16.
Have you seen vines like the pumpkin, the railroad creeper, kavali, watermelon or the grapvine? How do they grow?
Answer:
They have very soft, green and flexible stem. They grow with the help of a support.

Question 17.
For how many years do crops like bajra, wheat, corn, radish, marigold live?
Answer:
They live for about one year.

Question 18.
To which part of plants are butterflies and insects attracted?
Answer:
Butterflies and insects are attracted towards the flower of the plants.

Question 19.
What is the chain of bones in the centre of our back called?
Answer:
A vertibral column.

Maharashtra State Board Class 6 Science Textbook Solutions

• Natural Resources – Air, Water and Land Class 6 Science Textbook Solutions
• The Living World Class 6 Science Textbook Solutions
• Diversity in Living Things and their Classification Class 6 Science Textbook Solutions
• Disaster Management Class 6 Science Textbook Solutions
• Substances in the Surroundings – Their States and Proper Class 6 Science Textbook Solutionsties
• Substances in Daily Use Class 6 Science Textbook Solutions
• Nutrition and Diet Class 6 Science Textbook Solutions
• Our Skeletal System and the Skin Class 6 Science Textbook Solutions
• Motion and Types of Motion Class 6 Science Textbook Solutions
• Force and Types of Force Class 6 Science Textbook Solutions

Std 7 Science Chapter 6 Measurement of Physical Quantities Question Answer Maharashtra Board

Balbharti Maharashtra State Board Class 7 Science Solutions Chapter 6 Measurement of Physical Quantities Notes, Textbook Exercise Important Questions and Answers.

Class 7 Science Chapter 6 Measurement of Physical Quantities Question Answer Maharashtra Board

1. Write answers to the following questions in your own words:

Question a.
Why is the weight of the same object different on different planets?
Answer:
The weight of the same object is different on different planets because weight depends on the gravitational force of the planet and gravitational force on every planet is different so the weight also differs from planet to planet.

Question b.
What precautions will you take to make accurate measurements in day-to-day affairs?
Answer:
Following precautions will be taken to make accurate measurements in day to day affairs:

1. The balance should carry the stamp of standardisation by the department of weights and measures.
2. Balance should be stable and the pointer of the balance should be upright.
3. The underside of the pan should not be tampered with any other weight or layers of other metal.
4. The weight should be made of metal.

Question c.
What is the difference between mass and weight?
Answer:

2. Who is my companion? 

Class 7 Science Chapter 6 Measurement Of Physical Quantities Exercise Question 1.

Answer:

3. Explain giving examples. 

Question a.
Scalar quantity:
Answer:
A quantity that can be completely expressed by its magnitude alone is called a scalar quantity, e.g. length, breadth, area, mass, temperature, density, time, work. In all these examples a value with a unit is used to express quantities. Thus, we say that the length of a tunnel is 2 km.

Question b.
Vector quantity:
Answer:
The quantity that is expressed completely only.’ v when magnitude and direction are both given is called a vector quantity. Displacement, velocity are vector quantities e.g. a displacement of 20 km towards north, the aeroplane flying at a velocity of 500 km/hr towards Mumbai.

4. Explain, giving examples, the errors that occur while making measurements.

Question a.
Explain, giving examples, the errors that occur while making measurements.
Answer:
Major causes of errors in measurement are:

1. Not using the appropriate device.
2. Not using the device properly.

Example: While buying things at grocery shops and the vegetable market remember to look out for the following:

• The balance should carry the stamp of standardisation by the department of weights and measures.
• Balance should be stable. The pointer of the balance should be upright.
• No changes should be done on the underside of the pan of the balance.
• Weight should be made up of metals and it has to be standardized.

5. Give reasons:

Question a.
It is not proper to measure quantities by using body parts as units.
Answer:
It is not proper to measure quantities by using body parts as units because length of the body parts changes from person to person, so accurate measurement can not be found with the body parts as units.

Question b.
It is necessary to get the weights and measures standardized at regular intervals.
Answer:
It is necessary to get the weights and measures standardized at regular intervals because of that accurate weight and measurement can be taken. Errors will be avoided.

6. Explain the need for accurate measurement and the devices to be used for that.

Question a.
Explain the need for accurate measurement and the devices to be used for that.
Answer:

1. Measurement of substances that are precious or of great importance and used in very small quantities is done meticulously and accurately.
2. Due to advancements in technology, devices that measure very small magnitudes of quantities like distance, mass, time and temperature are available now.
3. e.g. distance and time in connection with very important sports competitions, mass of gold, body temperature etc.
4. Devices to be used for this are thermometer, digital balance (Analytical balance) etc.

Project:

Class 7 Science Chapter 6 Measurement Of Physical Quantities Question 1.
Collect information about various physical quantities used in day-to-day life and the devices used for their measurement.

Class 7 Science Chapter 6 Measurement of Physical Quantities Important Questions and Answers

Fill in the blanks:

Std 7 Science Chapter 6 Measurement Of Physical Quantities Question 1.
The amount of matter present in a substance is called ………………. .
Answer:
mass

Measurement Of Physical Quantities Class 7 Exercise Question 2.
…………. is the qualitative measure of the inertia of an object.
Answer:
mass

6. Measurement Of Physical Quantities Question 3.
The larger the mass, the ……………. is the inertia.
Answer:
greater

6.Measurement Of Physical Quantities Question 4.
Mass is a …………… quantity.
Answer:
scalar

Physical Quantities And Measurement Class 7 Question 5.
…………… does not change from place to place anywhere in the world.
Answer:
mass

Measurement Of Physical Quantities Class 7 Question 6.
The gravitational force that acts on a mass is called its ……………. .
Answer:
weight

6 Measurement Of Physical Quantities Question 7.
Wright is a …………… quantity.
Answer:
vector

Question 8.
System International (SI) is also called ………….. .
Answer:
metric system

Question 9.
In Egypt in ancient times, the distance from a man’s elbow to the tip of his middle finger was called a ………… .
Answer:
cubit

Question 10.
Gold was weighed in a unit called …………… .
Answer:
gun

Who is my companion?

Question 1.

Answer

Say whether true or false. Correct and rewrite the false statements:

Question 1.
The standards of the six fundamental units are kept in the National Physical Laboratory at New Delhi.
Answer:
True

Question 2.
Matter has a natural tendency to resist a change in its state, which is called inertia.
Answer:
True

Question 3.
Weight and mass are both equal quantities.
Answer:
False. Weight and mass are both different quantities

Question 4.
Work is a vector quantity.
Answer:
False. Work is a scalar quantity

Question 5.
Velocity is a scalar quantity.
Answer:
False. Velocity is a vector quantity

Question 6.
Unit of time in both the systems is second.
Answer:
True

Question 7.
Unit of mass in C.G.S. system is kilogram
Answer:
False. Unit of mass in C.G.S. system is gram

Question 8.
Symbol of unit of second is sec.
Answer:
False. Symbol of unit of second is ‘s’

Question 9.
1 cubic foot means 28.317 ml
Answer:
False. 1 cubic foot means 28.317 litres.

Question 10.
Vector quantity requires magnitude only.
Answer:
False. Vector quantity required magnitude and direction both.

Give scientific reasons:

Question 1.
Weight of our body on the moon is less than that on the earth.
Answer:

1. Gravitational power of moon is less than the earth.
2. Weight depends on the gravitational power of that place.
3. Since the gravitational power of the moon is less than that of the earth, the weight on moon is less than that on the earth.

Question 2.
Mass is a scalar quantity
Answer:
Mass is a scalar quantity because it can be completely expressed by its magnitude alone, so it is scalar quantity.

Question 3.
Weight is a vector quantity.
Answer:
Weight can be expressed completely only when magnitude and direction are both given so weight is a vector quantity.

Distinguish between the following:

Question 1.
Scalar quantity and Vector quantity
Answer:

Question 2.
M.K.S. system and C.G.S. system
Answer:

Define the following:

1. Mass: The amount of matter present in a substance is called mass.
2. Inertia: Matter has a natural tendency to resist a change in its state, which is called Inertia.
3. Weight: The gravitational force that acts on the mass is called its weight.
4. Physical Quantities: The quantities in day to day life which can be measured are called physical quantities.
5. Standardization: The process of checking things against a standard measure from time to time is called standardization.

Write answers to the following questions in your own words.

Question 1.
What is an atomic clock?
Answer:
An extremely accurate type of clock which is regulated by the vibrations of an atomic or molecular system such as caesium atom or ammonia is called atomic clock. It is used to maintain standard times of countries accurately.

Answer the following questions:

Question 1.
Why would the weight of an object be; maximum at the poles and minimum at the equator?
Answer:

1. The gravitational force that acts on the mass is called the weight.
2. The earth is not exactly spherical, it flattens at the poles.
3. As the distance increases the gravitational force decreases.
4. Therefore due to reduced distance at the poles compared to the equator, the weight is maximum at the poles than equator.

Question 2.
Why is the weight of an object at a high altitude less than its weight at the sea-level?
Answer:

1. The gravitational force that acts on the mass is called the weight.
2. The gravitational force is always inversely proportional to the distance.
3. So as the distance increases between the earth and the object, the gravitational force decreases.
4. The gravitational force by which the earth attracts an object towards its centre is called weight.
5. The weight at the sea-level is higher than at higher altitude, as the object is at a greater distance at higher altitudes compared to sea-level.

Maharashtra State Board Class 7 Science Textbook Solutions

• The Living World: Adaptations and Classification Class 7 Science Textbook Solutions
• Plants: Structure and Function Class 7 Science Textbook Solutions
• Properties of Natural Resources Class 7 Science Textbook Solutions
• Nutrition in Living Organisms Class 7 Science Textbook Solutions
• Food Safety Class 7 Science Textbook Solutions
• Measurement of Physical Quantities Class 7 Science Textbook Solutions
• Motion, Force and Work Class 7 Science Textbook Solutions
• Static Electricity Class 7 Science Textbook Solutions
• Heat Class 7 Science Textbook Solutions
• Disaster Management Class 7 Science Textbook Solutions