NCERT Class 8 Science Chapter 18 Pollution of Air and Water

NCERT Class 8 Science Chapter 18 Pollution of Air and Water Solutions to each chapter is provided in the list so that you can easily browse through different chapters NCERT Class 8 Science Chapter 18 Pollution of Air and Water and select need one. NCERT Class 8 Science Chapter 18 Pollution of Air and Water Question Answers Download PDF. NCERT Class 8 Science Solutions.

NCERT Class 8 Science Chapter 18 Pollution of Air and Water

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. CBSE Class 8 Science Solutions are part of All Subject Solutions. Here we have given NCERT Class 8 Science Chapter 18 Pollution of Air and Water and Textbook for All Chapters, You can practice these here.

Pollution of Air and Water

Chapter: 18

NCERT TEXT BOOK EXERCISES

Q. 1. What are the different ways in which water gets contaminated?

Ans. Water gets contaminated by following ways: 

(i) Water gets contaminated when sewage is disposed off in rivers.

(ii) Chemicals which are harmful and poisonous are thrown in water resources by various industrial units.

(iii) Harmful chemicals used in agricultural process gets mixed with ground water making it unfit for consumption.

(iv) Breeding of microorganisms in water make water polluted.

Q. 2. At an individual level, how can you help reduce air pollution?

Ans. We can plant tree to reduce the level of carbon dioxide. We can get our vehicles serviced well to reduce incomplete consumption of fuels. We can also reduce air pollution by saying no to crackers during Diwali celebrations.

Q. 3. Clear, transparent water is always fit for drinking. Comment.

Ans. The clear, transparent water may not always safe for drinking because it may still contain harmful microorganisms.

Q. 4. 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) To get clean water in every household, it is necessary that water reaching houses should be treated water. Water is treated in sewage plants, to make it free from physical, chemical and biological impurities.

(ii) Strict laws should be enforced on industrial units, which dispose polluted water in water resources.

(iii) Open defecation in water resources by slum dwellers should be strictly prohibited. 

(iv) Chlorine tablets should be distributed for purification of water during rainy season.

(v) People should be made aware and motivated to keep water resources clean.

Q. 5. Explain the differences between pure air and polluted air.

Ans. Pure air is free from harmful gases which can be poisonous in nature. Pure air has balanced quantity of all its constituent gases. It is free from other germs. This type of air is fit for breathing. On the other hand polluted air has poisonous gases and other suspended impurities like dust and smoke. It is unfit for consumption.

Q. 6. Explain circumstances leading to acid rain. How does acid rain affect us?

Ans. Some pollutants like sulphur dioxide and nitrogen dioxide reacts with the water vapour present in the atmosphere to form sulphuric acid and nitric acid . The acid drop down with rain, making the rain acidic. This is called acid rain. Acid rain affects us in many ways.

(i) Acid rain corrodes the marble of the monument.

(ii) Acid rain damages building and sculptural materials. 

(iii) Acid rain damages fresh water also.

(iv) Acid rain also damages our crops and also makes it poisonous.

(v) Acid rain damages the leaves of plants.

Q. 7. Which of the following is not a greenhouse gas?

(a) Carbon dioxide.

(b) Sulphur dioxide.

(c) Methane.

(d) Nitrogen.

Ans. (b) Sulphur dioxide.

Q. 8. Describe the ‘Green House Effect’ in your own words.

Ans. Greenhouse effect means warming the environment. When the rays of sun reach earth, some of the heat is absorbed by the earth. Rest of it is reflected back by the earth. Some of the heat is trapped by the environment of the earth. This causes warming of the environment, which is necessary for the sustaining life. This trapping of the heat is called greenhouse effect.

Q. 9. Prepare a brief speech on global warming. You have to deliver the speech in your class.

Ans. Continuous increase in the temperature of the earth is called global warming. It is caused by the pollution of air, excessive heat trapped by the greenhouse gases, because the amount of green house gases has increased in the environment. Global warming is a threating phenomenon because we may have to face dire consequences due to Global warming.

Q. 10. Describe the threat to the beauty of the Taj Mahal.

Ans. Increasing air pollution has posed a threat to the beauty of the Taj Mahal. Excessive poisonous gases and smoke has started to discolour the white marble of the Taj Mahal. Acid rains due to increasing air pollution has started to corrode the marble, thus making Taj Mahal loose its beauty.

Q. 11. Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

Ans. Excessive quantities which get washed from the fields, act as nutrients for algae to flourish. Once these algae die, they serve as food for decomposers like bacteria. A lot of oxygen in water body get used up. This results in a decrease in the oxygen level which may kill aquatic organisms.