NCERT Class VIII Science Solutions: Chapter 18-Pollution of Air and Water Part 2

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Question 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.

Answer:

We can take following measures:

  • Water should be treated properly to make it free from harmful germs, chemical and physical impurities.

  • Enforce laws to treat water and chemicals before disposing into water bodies.

  • Proper maintenance of pipes supplying tap water to avoid any corrosion, breakage and leakage.

  • Organize awareness programmers to keep water resources clean and make a habit of conserving water.

Question 5:

Explain the differences between pure air and polluted air.

Answer:

Pure air consists of a mixture of gases in proper amount which is good for living being. If by volume, about of this mixture is nitrogen, about is oxygen, carbon dioxide, argon, methane, ozone and water vapour are also present in very small quantities, and then it is called pure air.

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 polluted air.

Question 6:

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

Answer:

When harmful gases like sulphur dioxide and nitrogen dioxide, react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. The acids drop down with rain, making the rain acidic. This is called acid rain. Acid rain causes skin irritation, inhibits germination of plants, causes corrosion to bridges and building. It changes the fertility of the soil, destroys plants and aquatic life.

Image result for acid rain

Result for Acid Rain

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Question 7:

Which of the following is not a greenhouse gas?

  1. Carbon dioxide

  2. Sulphur dioxide

  3. Methane

  4. Nitrogen

Answer:

D. Nitrogen

Diagram shows greenhouse gas

Greenhouse Gas

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