NCERT Class VIII Science Solutions: Chapter 18-Pollution of Air and Water Part 3 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 15:

Name two gases which are mainly responsible for acid rain?


  1. Sulphur dioxide
  2. Nitrogen oxide
Gases Which Are Cause of Acid Rain

Question 16:

The quality of air at various locations is monitored regularly by government and other agencies? In what way can you use these data?


These data can be used to generate awareness about air pollution among people.

Question 17:

Combustion of fossil fuels generates a lot of air pollution. Can you suggest any two alternative sources of energy which do not cause any pollution?


Solar energy and wind energy.

Question 18:

Name any two water pollutants which are toxic for plants and animals.


Lead, arsenic, fluorides

Water Pollution


Question 19:

A lot of dry leaves are collected in a school garden and are burnt every day. Do you think that it is right to do so? If not, what should be done to dispose of the dry leaves?


It is not right to burn dry leaves as it causes air pollution. The right way to dispose of the dry leaves is to convert them into compost.

Question 20:

The level of air pollution is higher at a busy traffic intersection. Why?


A large number of automobiles stop for a short period at red light throughout the day and release a large quantity of gases which create air pollution.

Question 21:

Fill in the blanks with the help of words given in bracket after each sentence.

  1. When air is contaminated by ________ substances which have a ________ effect on both the ________ and ________, it is referred to as ________.

(air pollution, harmful, living, unwanted, non-living, pollutants) .

  1. Many ________ are responsible for causing ________ pollution. Petroleum ________ are a major source of ________ pollutants like ________ and ________.

(sulphur dioxide, refineries, industries, nitrogen dioxide, gaseous, liquid, people, air) .

  1. While ________ your teeth, leaving the ________ running may waste several ________ of water.

(tap, litres, brushing, washing, drops)

  1. Water which is suitable for ________ is called ________ water.

(washing, bathing, drinking, potable, soft) .

  1. Water which looks clean still has disease carrying ________ and ________ impurities.

(insects, microorganism, particles, dissolved, harmful) .


  1. When air is contaminated by unwanted substances which have a harmful effect on both the living and non-living, it is referred to as air pollution.
  2. Many industries are responsible for causing air pollution. Petroleum refineries are a major source of gaseous pollutants like sulphur dioxide and nitrogen dioxide.
  3. While brushing your teeth, leaving the tap running may waste several litres of water.
  4. Water which is suitable for drinking is called potable water.
  5. Water which looks clean still has disease carrying microorganism and dissolved impurities.

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