NCERT Exemplar solutions for Science [English] Class 8 chapter 18 - Pollution of Air and Water [Latest edition]

Air is a mixture of various gases. One of the gas is 21% part of the air and is essential for the survival of human beings. This gas is

Which of the following is not a source of air pollution?

Boojho wishes to contribute in reducing air pollution. Which vehicle should he use for going to school?

Which of the following is not a way to conserve water?

The type of pollution which is likely to affect Taj Mahal in Agra to a greater extent is

Incomplete combustion of fuel such as petrol and diesel gives

The phenomenon of marble cancer is due to

Potable water is the water which is

Which, of the following procedures will give you water free from all impurities?

A pond contains clean water. Which of the following activities will produce least pollution of water?

Trees help in reducing the pollution of our environment. Lakhs of trees are planted by people in the month of July every year. This occasion is called

Which of the following is not a greenhouse gas?

Name the chemicals which are used in refrigerators, air conditioners and damage ozone layer when released in air.

Name any two sources which causes air pollution due to Suspended Particulate Matter (SPM).

Name two gases which are mainly responsible for acid rain.

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

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?

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

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 off the dry leaves?

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

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)

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)

While ______ your teeth, leaving the ______ running may waste several ______ of Water.

(tap, litres, brushing, washing, drops)

Water which is suitable for ______ is called ______ water.

(washing, bathing, drinking, potable, soft)

Water which looks clean still has disease carrying ______ and ______ impurities.

(insects, microorganisms, particles, dissolved, harmful)

Match the items of Column A with those of Column B.

Find out the wrong statement and write it in its correct form.

We can survive for sometime without air but we cannot survive even for a few minutes without food.

Find out the wrong statement and write it in its correct form.

A brick kiln emits lot of smoke and other harmful gases causing air pollution.

Find out the wrong statement and write it in its correct form.

Carbon monoxide is produced by complete burning of fuels such as coal, petrol, diesel.

Find out the wrong statement and write it in its correct form.

Chlorination is a commonly used chemical method for killing germs in water.

Find out the wrong statement and write it in its correct form.

Water which is suitable for drinking is called soft water.

In the following statement, the underlined words are jumbled up. Write them in their correct form.

Air contains 78% ginroten and 21% gonexy. 

In the following statement, the underlined words are jumbled up. Write them in their correct form.

Vehicles produce high level of pollutants like carbon dioxide,  nitrogen oxides, nobrac moondexi and mosek.

In the following statement, the underlined words are jumbled up. Write them in their correct form.

Carbon dioxide, thaneme, nitrous oxide and water vapour are known as heengrouse sesga. 

In the following statement, the underlined words are jumbled up. Write them in their correct form.

Gangotri glacier in Himalaya has started melting because of lablog ringwam.

In the following statement, the underlined words are jumbled up. Write them in their correct form.

Whenever harmful substances such as wagese, toxic chemicals, silt, etc get mixed with water, the water becomes potdulle. 

What do CFCs stand for? Name some devices where CFCs are used. Why CFCs are considered as pollutants?

Why is it advised that industries should switch over to cleaner fuels such as CNG and LPG in the Taj Mahal zone in Agra?

It is said, ‘CO₂ contributes to global warming.’ Explain.

We should plant trees and nurture the ones already present in the neighbourhood. Why?

Explain the traditional ways of purifying water to make it fit for drinking.

How can we reduce, reuse and recycle water?

Read the paragraph and answer the questions following it.

Water is essential for life. Without water there would be no life. We usually take water as granted for its purity, but we must ensure the quality of water. Pollution of water originates from human activities. Through different paths, pollution reaches to groundwater. Easily identified source or place of pollution is called as point source, e.g. municipal and industrial discharge pipes, where pollutants enter the water source. Non-point sources of pollution are those where a source of pollution cannot be easily identified, e.g. agricultural run-off, acid rain, etc.

1. How do you classify the various sources of water pollution?
2. What are the point sources of water pollution?
3. Name any two non-point sources of water pollution?

Complete the crossword puzzle with the help of clues given below :

Across

1. Pollutant which was used in refrigerators and air conditioners. (18)

3. Produced on incomplete combustion of fuels (14)

6. This chemical protects our crops and is washed into water bodies from the field. (9)

Down

2. This layer protects us from harmful ultraviolet rays. (5)

4. It is essential for combustion. (6)

5. Disease which is caused by drinking contaminated water. (7)

7. River which is famous in India and sustains most of the northern, central and eastern Indian population. (5)