“Pollution of Air and Water” is Chapter 13 taken from the JKBOSE textbook of Science for students of Class 8th. In the previous post, I provided you with Questions and Answers for Chapter 12 Light. This post is about the Pollution of Air and Water Class 8 Question Answers. Before we move on to solutions you must have your basics clear. So, let me begin by giving you a brief overview of what you have studied in this chapter.
Pollution of Air and Water Class 8 Question Answers
Overview of Chapter
- AIR POLLUTION.
- HOW DOES THE AIR GET POLLUTED?
- CASE STUDY: THE TAJ MAHAL.
- GREENHOUSE EFFECT.
- WHAT CAN BE DONE?
- WATER POLLUTION.
- HOW DOES WATER GET POLLUTED?
- WHAT IS POTABLE WATER AND HOW WATER IS PURIFIED?
- WHAT CAN BE DONE?
The presence of a high concentration of harmful and poisonous substances in the environment (air, water or soil) is termed pollution. An unwanted substance which contaminates the environment is called a pollutant.
AIR POLLUTION: The contamination of air by unwanted substances which have a harmful effect on both the living and the non-living, it is referred to as air pollution.
HOW DOES THE AIR GET POLLUTED? Air gets polluted by two types of pollutants:
- Gaseous Pollutants: Sulphur dioxide (SO2), Carbon dioxide (CO2), Nitrogen dioxide (NO2), and Carbon monoxide (CO).
- Particulate Pollutants: Smoke, Dust, Fly ash, Smog.
The sources of pollution are classified into two groups:
- Natural Sources: Dust storms, forest fires, volcanoes and pollen grains.
- Man-made Sources: Exhaust gases emitted from vehicles, burning of fossil fuels, industries, nuclear power plants, etc.
CASE STUDY: THE TAJ MAHAL: India’s most famous tourist attraction, the Taj Mahal located in Agra has become a matter of concern. The experts have warned that pollutants in the air are discolouring its white marble and also corroding it slowly. It is due to acid rain. Acid rain corrodes the marble of the monument. The phenomenon is also called Marble cancer.
GREENHOUSE EFFECT: The heating up of the earth’s atmosphere due to the trapping of the sun’s heat rays by carbon dioxide gas in the atmosphere, is called the greenhouse effect. The greenhouse effect is caused due to presence of excessive greenhouse gases like carbon dioxide, methane etc. in the atmosphere.
WHAT CAN BE DONE: Air pollution can be controlled by adopting the following measures:
- By switching to CNG in moto vehicles in place of petrol and diesel.
- We should not burn dry leaves, papers and garbage in the open.
- We should grow more trees.
- Usage of alternative fuels such as solar energy, biogas, hydropower and wind energy.
- Join the “Say No to Crackers” campaign.
- We should use bicycles for short distances.
WATER POLLUTION: The contamination of water by the addition of unwanted and harmful substances is called water pollution.
HOW DOES WATER GET POLLUTED: The substance that pollutes water are called water pollutants. The major water pollutants are fertilisers, pesticides, sewage wastes and industrial wastes.
WHAT IS POTABLE WATER ANS HOW WATER IS PURIFIED: The water which is suitable for drinking is called potable water. Water which looks clear and has no smell doesn’t need to be potable. Water has to be treated to make it suitable for drinking. Various methods used to purify water are:
- Boiling.
- Filtration.
- Chlorination.
- Reverse Osmosis.
WHAT CAN BE DONE: Water pollution can be minimised by adopting the following measures:
- Treatment of sewage waste before discharging it into nearby rivers.
- Water treatment plants should be installed in all industrial plants.
- Excessive use of fertilisers and pesticides should be avoided.
- Laws for setting up industrial units should be strictly implemented.
- Create awareness among the people.
Pollution of Air and Water Class 8th Questions
Exercises
- What are the different ways in which water gets contaminated?
Ans. The different ways in which water gets contaminated by the following ways:
- Industrial Wastes from oil refineries, paper factories, and textile and sugar mills.
- Pesticides such as DDT etc.
- Fertilisers lead to water pollution.
- Untreated Sewage: Food wastes, detergents, microorganisms etc.
- At an individual level, how can you help reduce air pollution?
Ans. Water pollution can be minimised by adopting the following measures:
- Treatment of sewage waste before discharging it into nearby rivers.
- Water treatment plants should be installed in all industrial plants.
- Excessive use of fertilisers and pesticides should be avoided.
- Laws for setting up industrial units should be strictly implemented.
- Create awareness among the people.
- Clear, transparent water is always fit for drinking. Comment.
Ans. Water which looks clear doesn’t need to be always fit for drinking because it may contain disease-causing microorganisms like viruses and bacteria and dissolved impurities in it. So, it is necessary to purify water before using it.
- You are a member of the municipal body of your town.
Make a list of measures that would help your town to ensure the supply of clean water to all its residents.
Ans. I would take the following measures to ensure the supply of clean water to all its residents:
- I would try to replace faulty and leaky taps, water pipes and joints.
- I will create awareness among people about the shortage of clean water.
- Chlorination of water to purify it.
- I would initiate a drive to check that sewage waste is not disposed of in water bodies.
- Explain the differences between pure air and polluted air.
Ans.
| Pure Air | Polluted Air |
|---|---|
| 1. The air which does not contain any pollutant is termed pure air. | 1. The air which has pollutants in it is termed polluted air. |
| 2. It is free from harmful gases and microorganisms. | 2. It has harmful gases and diseases causing germs in it. |
| 3. Pure air does not have a foul smell. | 3. Polluted air may have a foul smell. |
| 4. It does not contain particulate matter like smoke or smog etc in it. | 4. It contains suspended particulate matter like fog, smoke and smog etc in it. |
| 5. It is beneficial for living organisms. | 5. It is harmful to living organisms. |
6. Explain circumstances leading to acid rain. How does acid rain affect us?
Ans. The gaseous pollutant like sulphur dioxide and nitrogen dioxide when reacts with water vapours present in the atmosphere forms sulphuric acid and nitric acid respectively. When these acids drop down with rain. It is termed acid rain. There are several industries like rubber processing industries, automobiles, and chemical and oil refineries which are responsible for producing these harmful gaseous pollutants. Acid rain affects us in the following ways:
a. It is responsible for the corrosion of marble buildings.
b. It damages our crops due to wilting and burning of leaves.
c. It damages aquatic life by making the water acidic.
d. It changes the rate of metabolism in organisms.
7. Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Methane
(d Nitrogen
Ans. Nitrogen is not a greenhouse gas.
8. Describe the ‘Green House Effect’ in your own words.
Ans. The trapping of solar radiation in the earth’s atmosphere which is responsible for heating up of earth’s surface is termed the greenhouse effect. The process of the greenhouse effect takes place in the following manner:
When sun rays enter the atmosphere, they warm the surface of the earth and it is necessary too but when an excess of greenhouse gases gets accumulated in the atmosphere it leads to excessive heating of the surface of the earth. When solar radiations fall on earth, some of them are absorbed by the surface of the earth and then released back into the atmosphere. Greenhouses gases like carbon dioxide, methane etc trap these radiations and do not allow the heat to escape from the atmosphere. It causes heating of the surface of the earth.
9. Prepare a brief speech on global warming that you have to make in your class.
Ans. The rise in the average temperature of the earth due to the greenhouse effect is called global warming. It is caused due to increased concentration of greenhouse gases in the atmosphere. The level of greenhouse gases like carbon dioxide, methane and nitrous oxide etc. are increasing excessively due to human activities like vehicular emissions, burning of fossil fuels etc. Global warming leads to serious effects on our lives.
10. Describe the threat to the beauty of the Taj Mahal.
Ans. The Taj Mahal is the most famous tourist attraction in India located in Agra. It has become a matter of concern due to increasing air pollution. There are several industries in and around the place where the Taj Mahal is located. These industries release harmful gaseous pollutants etc sulphur dioxide and nitrogen dioxide etc into the atmosphere. These gases when reacts with water vapours present in the air form sulphuric acid and nitric acid. These acids come down along with rain termed acid rain. The Taj Mahal is made of white marble. The acid rain corrodes the white marble of the Taj Mahal.
11. Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
Ans. The increased levels of nutrients in water bodies lead to increased growth of algae in them. When algae die, they serve as food for bacteria. While bacteria use dead algae as a source of food lot of oxygen is utilised in this process. This leads to a decreased level of dissolved oxygen in the water body. Due to decreased levels of oxygen aquatic organisms die or struggle for their survival.
That’s all about Pollution of Air and Water Class 8 Question Answers. Hope it has helped. Do share your views about this post in the comment section below.
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