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Page No 282:

Question A:

Answer:



1. Chlorination
2. Pollutant
3. Eutrophication
4. Bioconcentration

Page No 282:

Question B.1:



1. Chlorination
2. Pollutant
3. Eutrophication
4. Bioconcentration

Answer:

(c) both (a) and (b)
Eutrophication is caused due to the presence of excessive nitrates and phosphates in water.

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Question B.2:

(c) both (a) and (b)
Eutrophication is caused due to the presence of excessive nitrates and phosphates in water.

Answer:

(b) bio-concentration
The accumulation of harmful pesticides in the living body is known as bio-concentration.

Page No 282:

Question B.3:

(b) bio-concentration
The accumulation of harmful pesticides in the living body is known as bio-concentration.

Answer:

(a) cleaning the Ganga
Ganga Action Plan deals with cleaning the Ganga.

Page No 282:

Question B.4:

(a) cleaning the Ganga
Ganga Action Plan deals with cleaning the Ganga.

Answer:

(b) carbon dioxide
Excessive release of carbon dioxide causes the greenhouse effect.
Note: Methane is also a greenhouse gas. But the excessive release of carbon dioxide in recent years has led to the greenhouse effect. Methane is not a major pollutant; therefore, it is not considered a cause of the greenhouse effect.

Page No 282:

Question B.5:

(b) carbon dioxide
Excessive release of carbon dioxide causes the greenhouse effect.
Note: Methane is also a greenhouse gas. But the excessive release of carbon dioxide in recent years has led to the greenhouse effect. Methane is not a major pollutant; therefore, it is not considered a cause of the greenhouse effect.

Answer:

(c) both (a) and (b)
Acid rain damages old monuments and statues.

Page No 282:

Question B.6:

(c) both (a) and (b)
Acid rain damages old monuments and statues.

Answer:

(a) fly ash
Fly ash is a type of suspended particulate matter (SPM).

Page No 282:

Question B.7:

(a) fly ash
Fly ash is a type of suspended particulate matter (SPM).

Answer:

(b) nitrogen
Nitrogen is not a greenhouse gas.



Page No 283:

Question 1:

(b) nitrogen
Nitrogen is not a greenhouse gas.

Answer:

Steps that should be taken to stop pollution of mountains:
(a) Volunteers should be selected for cleaning up mountains.
(b) Use of plastic materials should be banned on mountains.
(c) Mountaineers should be advised not to leave their used oxygen tanks and other supplies on mountains.

Page No 283:

Question 2:

Steps that should be taken to stop pollution of mountains:
(a) Volunteers should be selected for cleaning up mountains.
(b) Use of plastic materials should be banned on mountains.
(c) Mountaineers should be advised not to leave their used oxygen tanks and other supplies on mountains.

Answer:

River water looks clean, but it is not suitable for drinking because it contains large amounts of dissolved and suspended impurities. Large amounts of harmful substances are thrown into the rivers which make the water unfit for drinking. Hence, it is essential to purify it before drinking.

Page No 283:

Question 3:

River water looks clean, but it is not suitable for drinking because it contains large amounts of dissolved and suspended impurities. Large amounts of harmful substances are thrown into the rivers which make the water unfit for drinking. Hence, it is essential to purify it before drinking.

Answer:

Oil spill is a major problem for aquatic life because it pollutes water and aquatic organisms are not able survive in polluted water bodies. Oil materials released in water bodies affect the growth and reproduction of aquatic animals by killing their larvae.

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Question 4:

Oil spill is a major problem for aquatic life because it pollutes water and aquatic organisms are not able survive in polluted water bodies. Oil materials released in water bodies affect the growth and reproduction of aquatic animals by killing their larvae.

Answer:

CNG is a smokeless fuel. In comparison to diesel, CNG emits less carbon particles and harmful gases (such as carbon monoxide) on ignition. Hence, CNG is considered as a better fuel in vehicles over diesel.

Page No 283:

Question B.8:

CNG is a smokeless fuel. In comparison to diesel, CNG emits less carbon particles and harmful gases (such as carbon monoxide) on ignition. Hence, CNG is considered as a better fuel in vehicles over diesel.

Answer:

(a) bronchitis
Bronchitis is caused by air pollution.

Page No 283:

Question B.9:

(a) bronchitis
Bronchitis is caused by air pollution.

Answer:

(d) all of these
All the options are preventive measures to control water pollution.

Page No 283:

Question B.10:

(d) all of these
All the options are preventive measures to control water pollution.

Answer:

(d) all of these
In cities and towns, water should be purified by sedimentation, filtration and chlorination.

Page No 283:

Question C:

(d) all of these
In cities and towns, water should be purified by sedimentation, filtration and chlorination.

Answer:

1. Hydrogen sulphide tarnishes silver objects.
2. Greenhouse effect is produced due to increase in greenhouse gases.
3. Acid rains damage old monuments and old statues.
4. Luxuriant growth of algae in a water body is called eutrophication.
5. Carbon dioxide is a greenhouse gas.

Page No 283:

Question D:

1. Hydrogen sulphide tarnishes silver objects.
2. Greenhouse effect is produced due to increase in greenhouse gases.
3. Acid rains damage old monuments and old statues.
4. Luxuriant growth of algae in a water body is called eutrophication.
5. Carbon dioxide is a greenhouse gas.

Answer:

Column A  Column B
1. Bioconcentration (c) Pesticides
2. Eutrophication (e) Fertilisers
3. Greenhouse effect (d) Carbon dioxide
4. Acid rain  (b) Sulphur dioxide
5. Chlorine     (a) Purify water

Page No 283:

Question E:

Column A  Column B
1. Bioconcentration (c) Pesticides
2. Eutrophication (e) Fertilisers
3. Greenhouse effect (d) Carbon dioxide
4. Acid rain  (b) Sulphur dioxide
5. Chlorine     (a) Purify water

Answer:

1. (T) True
Water pollution is hazardous to all life forms.
2. (F) False
Pure drinking water does not have any taste.
3. (T) True
Sulphur dioxide gas eats up limestone and marble of buildings.
4. (T) True
Acid rains are harmful for aquatic life.
5. (F) False
Bioconcentration is harmful for living organisms.



Page No 284:

Question A.1:

1. (T) True
Water pollution is hazardous to all life forms.
2. (F) False
Pure drinking water does not have any taste.
3. (T) True
Sulphur dioxide gas eats up limestone and marble of buildings.
4. (T) True
Acid rains are harmful for aquatic life.
5. (F) False
Bioconcentration is harmful for living organisms.

Answer:

Harmful gases such as sulphur dioxide, nitrogen dioxide and carbon monoxide, unburnt hydrocarbons, lead compounds and soot are emitted from vehicles.

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Question A.2:

Harmful gases such as sulphur dioxide, nitrogen dioxide and carbon monoxide, unburnt hydrocarbons, lead compounds and soot are emitted from vehicles.

Answer:

Vehicles are the major source of air pollution in metro cities.

Page No 284:

Question A.3:

Vehicles are the major source of air pollution in metro cities.

Answer:

Sewage should not be dumped into the rivers because it pollutes their water.

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Question A.4:

Sewage should not be dumped into the rivers because it pollutes their water.

Answer:

Potable water refers to that water which is free from all kinds of impurities and is fit for drinking.

Page No 284:

Question A.5:

Potable water refers to that water which is free from all kinds of impurities and is fit for drinking.

Answer:

Greenhouse gases are those gases that cause the greenhouse effect.
Examples: Carbon dioxide and methane.

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Question A.6:

Greenhouse gases are those gases that cause the greenhouse effect.
Examples: Carbon dioxide and methane.

Answer:

At the individual level, one should use CNG instead of petrol and diesel for vehicles. Moreover, use of public transport can also reduce air pollution.

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Question A.7:

At the individual level, one should use CNG instead of petrol and diesel for vehicles. Moreover, use of public transport can also reduce air pollution.

Answer:

Increase in the concentration of carbon dioxide gas is responsible for global warming.

Page No 284:

Question A.8:

Increase in the concentration of carbon dioxide gas is responsible for global warming.

Answer:

Four pollutants that cause water pollution are chemical fertilisers, pesticides, oils and heavy metals.

Page No 284:

Question A.9:

Four pollutants that cause water pollution are chemical fertilisers, pesticides, oils and heavy metals.

Answer:

Sand, gravel, charcoal and alum are commonly used in Indian villages to purify water.

Page No 284:

Question A.10:

Sand, gravel, charcoal and alum are commonly used in Indian villages to purify water.

Answer:

Pesticides contain harmful chemicals that are toxic for living organisms. If pesticides mix in water bodies, they pollute the water bodies. Pesticides present in water get accumulated in the bodies of aquatic animals (bio-concentration) and may ultimately end up harming human-beings that consume these aquatic animals.

Page No 284:

Question B.1:

Pesticides contain harmful chemicals that are toxic for living organisms. If pesticides mix in water bodies, they pollute the water bodies. Pesticides present in water get accumulated in the bodies of aquatic animals (bio-concentration) and may ultimately end up harming human-beings that consume these aquatic animals.

Answer:

Pollution: It refers to the contamination of abiotic factors such as air, water and soil by substances that reduce their quality and may be harmful to living organisms.
Pollutant: The substances that cause pollution are called pollutants.

Page No 284:

Question B.2:

Pollution: It refers to the contamination of abiotic factors such as air, water and soil by substances that reduce their quality and may be harmful to living organisms.
Pollutant: The substances that cause pollution are called pollutants.

Answer:

The four sources of water pollution are:
(a) Sewage
(b) Industrial wastes
(c) Chemical fertilisers and pesticides
(d) Petroleum oil

Page No 284:

Question B.3:

The four sources of water pollution are:
(a) Sewage
(b) Industrial wastes
(c) Chemical fertilisers and pesticides
(d) Petroleum oil

Answer:

Greenhouse effect refers to the process of keeping a closed area warm by trapping the heat inside and not allowing it to escape out.

Page No 284:

Question B.4:

Greenhouse effect refers to the process of keeping a closed area warm by trapping the heat inside and not allowing it to escape out.

Answer:

The two harmful effects of air pollution are:
(a) Suspended particulate matter in air causes diseases such as asthma, bronchitis and allergic cold.
(b) Air pollutants also cause irritation in eyes, throat and lungs.

Page No 284:

Question B.5:

The two harmful effects of air pollution are:
(a) Suspended particulate matter in air causes diseases such as asthma, bronchitis and allergic cold.
(b) Air pollutants also cause irritation in eyes, throat and lungs.

Answer:

Bio-concentration of pesticides refers to the accumulation of toxic pesticides in living organisms through consumption of polluted water.

Page No 284:

Question B.6:

Bio-concentration of pesticides refers to the accumulation of toxic pesticides in living organisms through consumption of polluted water.

Answer:

Extreme depletion of dissolved oxygen in a water body due to the overgrowth of aquatic weeds and other microorganisms, causing damage to aquatic life is called eutrophication. It occurs when fertilisers are discharged into water bodies along with the run-off from agricultural lands.

Page No 284:

Question B.7:

Extreme depletion of dissolved oxygen in a water body due to the overgrowth of aquatic weeds and other microorganisms, causing damage to aquatic life is called eutrophication. It occurs when fertilisers are discharged into water bodies along with the run-off from agricultural lands.

Answer:

The two harmful effects of water pollution are:
(a) Water polluted by various pathogens can cause human diseases such as cholera, typhoid and jaundice.
(b) Water pollutants disturb the ecological balance of water bodies by promoting the growth of certain life forms that are harmful to other life forms.

Page No 284:

Question B.8:

The two harmful effects of water pollution are:
(a) Water polluted by various pathogens can cause human diseases such as cholera, typhoid and jaundice.
(b) Water pollutants disturb the ecological balance of water bodies by promoting the growth of certain life forms that are harmful to other life forms.

Answer:

Water gets polluted by the discharge of industrial wastes, domestic wastes, sewage, oils, and other pollutants in water bodies. These pollutants bring about undesirable changes in the biological, physical and chemical properties of water bodies, thereby making them unfit for consumption.

Page No 284:

Question B.9:

Water gets polluted by the discharge of industrial wastes, domestic wastes, sewage, oils, and other pollutants in water bodies. These pollutants bring about undesirable changes in the biological, physical and chemical properties of water bodies, thereby making them unfit for consumption.

Answer:

Solid particles of very minute size that are present in air are known as suspended particulate matter (SPM).
SPM pollutants are dangerous because of the following reasons:
(a) They can cause lung cancer when inhaled. The hair present in our nose is not able to filter them out because of their minute size.
(b) They get deposited on the leaves of plants, thereby restricting the process of photosynthesis.

Page No 284:

Question B.10:

Solid particles of very minute size that are present in air are known as suspended particulate matter (SPM).
SPM pollutants are dangerous because of the following reasons:
(a) They can cause lung cancer when inhaled. The hair present in our nose is not able to filter them out because of their minute size.
(b) They get deposited on the leaves of plants, thereby restricting the process of photosynthesis.

Answer:

The function of catalytic converter in vehicles is to convert harmful pollutants such as carbon monoxide and nitrogen oxides into non-toxic substances such as nitrogen, water and carbon dioxide.

Page No 284:

Question C.1:

The function of catalytic converter in vehicles is to convert harmful pollutants such as carbon monoxide and nitrogen oxides into non-toxic substances such as nitrogen, water and carbon dioxide.

Answer:

When rainwater in clouds gets mixed with sulphur dioxide present in the atmosphere, this mixture, i.e., sulphuric acid, precipitates in the form of rain. This phenomenon is called acid rain.
It is mainly caused due to the burning of coal that contains sulphur as impurity and emits sulphur dioxide on burning. In the atmosphere, this sulphur dioxide reacts with oxygen to form sulphur trioxide. Sulphur trioxide, in turn reacts with the water in the clouds to form sulphuric acid.
Acid rain severely affects the growth of plants and animals and destroys buildings by eroding their stone and brickwork (e.g., Taj Mahal).
It also causes skin cancer and allergies in human beings.

Page No 284:

Question C.2:

When rainwater in clouds gets mixed with sulphur dioxide present in the atmosphere, this mixture, i.e., sulphuric acid, precipitates in the form of rain. This phenomenon is called acid rain.
It is mainly caused due to the burning of coal that contains sulphur as impurity and emits sulphur dioxide on burning. In the atmosphere, this sulphur dioxide reacts with oxygen to form sulphur trioxide. Sulphur trioxide, in turn reacts with the water in the clouds to form sulphuric acid.
Acid rain severely affects the growth of plants and animals and destroys buildings by eroding their stone and brickwork (e.g., Taj Mahal).
It also causes skin cancer and allergies in human beings.

Answer:

Carbon monoxide poisoning refers to the inhalation of carbon monoxide gas. Carbon monoxide is considered to be a dangerous pollutant because it competes with oxygen to bind with haemoglobin in the blood of human bodies. It has 200 times more affinity towards haemoglobin than oxygen. This ultimately reduces the availability of oxygen to the body tissue and leads to suffocation and death of the organism. Also, it is an odourless gas; therefore, it cannot be detected through smell. This makes it even more dangerous.

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Question C.3:

Carbon monoxide poisoning refers to the inhalation of carbon monoxide gas. Carbon monoxide is considered to be a dangerous pollutant because it competes with oxygen to bind with haemoglobin in the blood of human bodies. It has 200 times more affinity towards haemoglobin than oxygen. This ultimately reduces the availability of oxygen to the body tissue and leads to suffocation and death of the organism. Also, it is an odourless gas; therefore, it cannot be detected through smell. This makes it even more dangerous.

Answer:

Global warming: The heating up of the atmosphere because of greenhouse gases (carbon dioxide and methane) that trap the heat reflected by the Earth, thereby causing an increase in the Earth's temperature, is called global warming.
Ozone depletion: Depletion of ozone layer refers to the reduction in the concentration of this layer. It is caused by ozone-depleting substances (ODSs), such as chloro-fluoro carbons (CFCs), halons, methyl bromide, nitrogen oxide and chlorine.
Greenhouse gases: These are the gases that cause the greenhouse effect. They trap the heat and do not allow it to escape to space.

Page No 284:

Question C.4:

Global warming: The heating up of the atmosphere because of greenhouse gases (carbon dioxide and methane) that trap the heat reflected by the Earth, thereby causing an increase in the Earth's temperature, is called global warming.
Ozone depletion: Depletion of ozone layer refers to the reduction in the concentration of this layer. It is caused by ozone-depleting substances (ODSs), such as chloro-fluoro carbons (CFCs), halons, methyl bromide, nitrogen oxide and chlorine.
Greenhouse gases: These are the gases that cause the greenhouse effect. They trap the heat and do not allow it to escape to space.

Answer:

Following methods are used to prevent water pollution:
(i) Treating sewage in sewage treatment plants allows clean water to be discharged into water bodies.
(ii) Treating industrial wastes to remove harmful chemicals
(iii) Pesticides and fertilisers should be used in a limited amount.
(iv) Planting trees and shrubs along the banks of the rivers



Page No 285:

Question C.5:

Following methods are used to prevent water pollution:
(i) Treating sewage in sewage treatment plants allows clean water to be discharged into water bodies.
(ii) Treating industrial wastes to remove harmful chemicals
(iii) Pesticides and fertilisers should be used in a limited amount.
(iv) Planting trees and shrubs along the banks of the rivers

Answer:

Methods to purify water supplied to our homes:
(a) Sedimentation and decantation: In this process, large-sized impurities are made to settle down at the bottom of the tank by the process of sedimentation.
The clear water is then separated from the sediments through the process of decantation.
(b) Loading: To remove smaller-sized particles, water is treated with alum that makes these particles heavier. Consequently, they settle down at the bottom and can be separated from the water.
(c) Filtration: Water is then filtered by passing it through sand filters. This makes water free from impurities.
(d) Chlorination: Finally, to remove germs from water, it is treated with chlorine.

Page No 285:

Question C.6:

Methods to purify water supplied to our homes:
(a) Sedimentation and decantation: In this process, large-sized impurities are made to settle down at the bottom of the tank by the process of sedimentation.
The clear water is then separated from the sediments through the process of decantation.
(b) Loading: To remove smaller-sized particles, water is treated with alum that makes these particles heavier. Consequently, they settle down at the bottom and can be separated from the water.
(c) Filtration: Water is then filtered by passing it through sand filters. This makes water free from impurities.
(d) Chlorination: Finally, to remove germs from water, it is treated with chlorine.

Answer:

Harmful effects of water pollution:
(a) Water polluted by various pathogens can cause human diseases such as cholera, typhoid, jaundice, dysentery and hepatitis.
(b) Water pollutants disturb the ecological balance of water bodies by promoting the growth of certain life forms that are harmful to other life forms.
(c) Increase in the concentration of organic pollutants causes an increase in the bacterial population, which uses the available oxygen. The lack of oxygen kills fish and other animals.
(d) Discharge of untreated industrial wastes, rich in heavy metals, acids and alkalis, results in the death of useful microorganisms that contribute to the self-purification process of water bodies.
(e) Thermal pollution causes a sudden change in the temperature of water bodies that may kill the larvae of various animals and affect the breeding of aquatic animals.

Page No 285:

Question C.7:

Harmful effects of water pollution:
(a) Water polluted by various pathogens can cause human diseases such as cholera, typhoid, jaundice, dysentery and hepatitis.
(b) Water pollutants disturb the ecological balance of water bodies by promoting the growth of certain life forms that are harmful to other life forms.
(c) Increase in the concentration of organic pollutants causes an increase in the bacterial population, which uses the available oxygen. The lack of oxygen kills fish and other animals.
(d) Discharge of untreated industrial wastes, rich in heavy metals, acids and alkalis, results in the death of useful microorganisms that contribute to the self-purification process of water bodies.
(e) Thermal pollution causes a sudden change in the temperature of water bodies that may kill the larvae of various animals and affect the breeding of aquatic animals.

Answer:

When rainwater in clouds gets mixed with sulphur dioxide present in the atmosphere, this mixture, i.e., sulphuric acid, precipitates in the form of rain. This phenomenon is called acid rain.
It is caused mainly due to the burning of coal that contains sulphur as impurity and emits sulphur dioxide on burning. This sulphur dioxide in the atmosphere reacts with oxygen to form sulphur trioxide, which, in turn, reacts with the water in the clouds to form sulphuric acid.
Sulphur dioxide present in acid rain eats up marble and limestone of the buildings. In this way, acid rain damages the old monuments.

Page No 285:

Question C.8:

When rainwater in clouds gets mixed with sulphur dioxide present in the atmosphere, this mixture, i.e., sulphuric acid, precipitates in the form of rain. This phenomenon is called acid rain.
It is caused mainly due to the burning of coal that contains sulphur as impurity and emits sulphur dioxide on burning. This sulphur dioxide in the atmosphere reacts with oxygen to form sulphur trioxide, which, in turn, reacts with the water in the clouds to form sulphuric acid.
Sulphur dioxide present in acid rain eats up marble and limestone of the buildings. In this way, acid rain damages the old monuments.

Answer:

The heating up of the atmosphere because of greenhouse gases (carbon dioxide and methane) that trap the heat reflected by the Earth, thereby causing an increase in the Earth's temperature, is called global warming.

Harmful effects of global warming:
(i) It causes change in the weather and precipitation patterns on Earth.
(ii) It causes melting of polar ice caps and leads to rise in sea levels.



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