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Important Questions for CBSE Class 8 Science Chapter 18 - Pollution of Air and Water

CBSE

Class 8 Important Question

Science

Chapter 18: Pollution Of Air And Water

CBSE Class 8 Science Chapter-18 Pollution of Air and Water Important Questions - Free PDF Download

Free PDF download of Important Questions with solutions for CBSE Class 8 Science Chapter 18 - Pollution of Air and Water prepared by expert Science teachers from latest edition of CBSE(NCERT) books. Register Online for Class 8 Science tuition on Vedantu.com to score more marks in your examination. Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for the better solutions ,they can download Class 8 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

Study Important Questions for Class 8 Science Chapter 18 – Pollution of Air and Water

Very Short Answer Questions: 1 Mark

1. Pollution is mainly caused by __________.

A. human activities

B. trees

C. sea waves

D. heavy rains

Ans: A. human activities

2. In which one of the following chlorofluorocarbons are used?

A. refrigerators

B. air conditioners

C. perfumes

D. all of these

Ans: D. All of these

3. Which one of the following is present the most in air.

A. oxygen

B. carbon dioxide

C. nitrogen

D. argon

Ans: C. Nitrogen

4. CNG is a __________.

A. polluted fuel

B. clean fuel

C. harmful fuel

D. none of the above

Ans: B. Clean Fuel

5. Most polluted river in the world is ____________.

A. Yamuna

B. Cauvery

C. Chenab

D. Ganga

Ans: D. Ganga

6. Which of the following is NOT a greenhouse gas?

A. sulphur dioxide

B. carbon dioxide

C. nitrogen

D. methane

Ans: C. Nitrogen

7. Name the gases present in air.

Ans: Gases present in air are as follows:

Nitrogen
Oxygen
Carbon Dioxide
Argon
Methane etc.

8. What are the natural causes of air pollution?

Ans: Natural causes of air pollution are as follows:

Forest Fire
Storms etc.

9. How is carbon monoxide produced?

Ans: Carbon monoxide is formed due to incomplete burning of products like petrol, diesel, kerosene etc.

10. What is smog?

Ans: Dust combined with smoke is known as smog.

11. What are the respiratory disorders caused by air pollution?

Ans: Disorders caused by air pollution:

Asthma
Emphysema
Bronchitis.

12. Name the two major gases responsible for corrosion of the marble of Taj Mahal.

Ans: Gases responsible for corrosion of Taj Mahal are as follows:

Sulphur Dioxide
Nitrogen Dioxide

13. Expand - CNG and LPG?

Ans: CNG - Compressed Natural Gas.

LPG – Liquefied Petroleum Gas

14. Which gases can be called greenhouse gases?

Ans: Gases that are called as greenhouse gases are as follows:

Carbon Dioxide
Methane
Nitrous Oxide

15. What is potable water?

Ans: Water which is fit for drinking is called potable water.

16. Write any two ways in which water can be made safe for drinking.

Ans: Ways in which water can be made safe for drinking:

Boiling
Filtration
Chlorination

Short Answer Questions: 3 Marks

17. What is air pollution?

Ans: When air is contaminated by unwanted substances which have a harmful effect on both the living and the non-living, it is referred to as air pollution. Substances which contaminate air are known as air pollutants. It is an undesirable change in atmosphere and can cause very diseases in humans, animals and plants.

18. What is acid rain?

Ans: The sulphur dioxide and nitrogen dioxide present in air which are released from various factories combines with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. These acids pour down along with rain and this phenomenon is called acid rain. Acid rain can be harmful for both living and non living things.

In humans it can cause rashes, itching, and other skin problems.
Acid rain damages plant leaves.
It also causes yellowing of various monuments.
It makes sea/river water unfit for aquatic animals.

19. What are the causes of the increasing amount of carbon dioxide in air?

Ans: Various causes of increase in carbon dioxide in atmosphere:

Burning of fossil fuels at a high rate in factories.
Carbon emission by vehicles.
Deforestation.

20. Define water pollution.

Ans: Addition of unwanted and harmful substances in water which makes it unfit for drinking and other purposes is known as water pollution. Substances which contaminate water are called water pollutants. Water pollution increases the risk for aquatic animals as the pH and temperature of water changes. It also increases the growth of algae which reduces oxygen level in water bodies.

21. Write in short about the Ganga Action Plan.

Ans: Ganga Action Plan is an ambitious plan to save the river Ganga launched in 1985. It aimed to reduce the pollution levels in the river. However, the increasing population and industrialisation have already damaged the river beyond repair. Now, the Government of India has launched a new initiative known as National Mission for Clean Ganga (NMCG) in 2016.

22. Describe the greenhouse effect.

Ans: Greenhouse effect is a phenomenon in which the sun rays are captured and absorbed by the greenhouse gases such as carbon dioxide, CFCs etc which leads to increase in earth’s temperature.

23. What is global warming?

Ans: The gradual increase in earth’s temperature due to excessive release of carbon dioxide, methane, CFCs which causes greenhouse effect is called global warming. The harmful effects of global warming include:

Threat to aquatic life
Flooding
Loss of habitation for both aquatic animals as well as humans etc.

24. List some of the sources of air pollution.

Ans: Some sources of air pollution are as follows:

Carbon dioxide released from industries and vehicles.
Forest fire
Burning of fire woods and dung cakes.
Storms.
Mining activities.

25. How do environmental problems affect people’s health?

Ans: Environment problems can cause various physical, biological and chemical hazards in humans due to air, water, or soil pollution. Some of them are listed below:

Respiratory diseases like asthma, bronchitis.
Cancer.
Heart diseases.
Water borne diseases like diarrheal infection.

26. Clear transparent water is fit for drinking, do you agree?

Ans: No, clear and transparent water is not always fit for drinking. There are possibilities of disease causing microbes and dissolved impurities in the clear and transparent water as well which are not visible from naked eyes. So, it is important to purify water before drinking. Water can be purified by using water purifiers, chlorination or boiling.

Long Answer Questions: 5 Marks

27. What steps should be taken to minimise air pollution?

Ans: Some of the steps that we can add in our day to day life to minimize air pollution are as follows:

Use of clear fuel such as CNG in vehicles instead of petrol/diesel.
Use bicycles for a small distance.
Cooking of food on LPF gases instead of fire woods.
Turn off the vehicles on red lights to lesser carbon emission.
Use solar/nuclear energies in big factories instead of coal.

28. What are the differences between pure water and polluted water?

Ans: The differences between pure water and polluted water are as follows:

Pure Water	Polluted Water
Water is free from any harmful bacteria or chemical substances.	Water is contaminated with harmful bacteria and chemicals.
It is fit for drinking.	It is unfit for drinking.
It is visibly clear.	Most of the time it is seen as unclear, dark and has a bad odour but sometimes it is also clear.
It has a high level of oxygen.	It has very low oxygen content.

28. Why does the increased level of chemicals in the water affect the survival of aquatic organisms?

Ans: The discharge from factories mixes with various water bodies. The chemical discharges add unwanted and harmful substances into the water. This causes water pollution. Some of the chemicals that are mixed in water are lead, fluorides, carbon monoxide etc. These chemicals are harmful for aquatic plants and animals.Sometimes, the chemicals released also help in algae blooming which takes up a lot of oxygen from water. Lack of oxygen can kill aquatic organisms as well. Therefore, increased levels of chemicals in water is unhealthy for aquatic life.

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Conclusion

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FAQs on Important Questions for CBSE Class 8 Science Chapter 18 - Pollution of Air and Water

1. What is pollution?

The introduction of toxins into the environment that has a negative impact on it is known as pollution. Pollution can be any kind of material or energy. The components of pollution, which include both naturally occurring toxins and imported materials/energies, are referred to as pollutants.

2. What is air pollution?

Air pollution is the contamination of the atmosphere's atmosphere by compounds that are dangerous to the health of people and other living things, or that impair the climate or materials. Gases, particles, and biological molecules are just a few of the various sorts of air pollution.

3. What is water pollution?

The term "water pollution" refers to the contamination of water bodies, typically as a result of human activity, which has a detrimental impact on the uses of the water. Lakes, rivers, oceans, aquifers, reservoirs, and groundwater are all examples of bodies of water. Contaminants are introduced into these water bodies, which causes water pollution.

4. How does air pollution affect the environment?

There are numerous ways in which air pollution can harm trees and crops. Reduced development and survival of tree seedlings, decreased yields of agricultural crops and commercial forests, and increased vulnerability of plants to disease, pests, and other environmental pressures are all effects of ground-level ozone (such as harsh weather).

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Because Vedantu can provide conceptually clear answers to the questions in CBSE Class 8 Maths Chapter 10: Visualizing Solid Shapes, it is regarded as a competitive option.

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