NCERT Class VIII Science Solutions: Chapter 5-Coal and Petroleum Part 4

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Question 20:

Sunlight and air are inexhaustible natural resources. Comment.


These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities.

Question 21:

Some natural resources are given in a box. Classify them into the exhaustible and inexhaustible natural resources.

Air, coal, natural gas, sunlight, petroleum, minerals, forests, oxygen.


Exhaustible natural resources are

Coal, natural gas, petroleum, minerals, forests.

Inexhaustible natural resources are

Air, sunlight, oxygen.

Image of difference between exhaustible and inexhaustible

Difference between Exhaustible and Inexhaustible

Image of difference between exhaustible and inexhaustible

Question 22:

Write two important uses of coke.


It is used for extraction of many metals and also for the manufacture of steel.

Question 23:

Write the characteristics and some important uses of coal.


Coal is black in colour and hard as stone. It is one of the fuels used to cook food. Earlier it was used in railway engines to produce steam to run the engine. It is used as fuel in thermal power plants to produce electricity and in various other industries.

Question 24:

Look at Fig where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?

Result for petroleum and natural gas deposits

Petroleum and Natural Gas Deposits

Result for petroleum and natural gas deposits


Oil is lighter than water hence floats over it.

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