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Coal and Petroleum Notes for Class 8, Ideal for CBSE based on NCERT

Important topics covered in Coal and petroleum notes:

  • Introduction
  • Natural Resources
  • Inexhaustible Natural Resources
  • Exhaustible Natural resources
  • Coal
  • Petroleum
  • Natural Gas
  • Limited Natural Resources


  • In our day to day life, we use various materials to fulfil our needs.
  • Some of them are naturals while others are artificial/man-made resources.
  • Some example of natural resources are:
Natural Resources Man-made Resources
Silk Clothes
Wood Paper
Leather Shoes
Rubber Tyre
Fur Pillow
Fabrics Suit

Natural Resources:

natural resources and its types

  • The resources which are present in nature and is used by living organisms in various ways are called natural resources.
  • These resources can be exploited for economic gain.
  • The raw material for the food we eat, the clothes we wear is obtained from natural resources.

Types of natural resources:

There are two types of natural resources. They are:

  1. Inexhaustible resources
  2. Exhaustible resources

Inexhaustible resources:

inexhaustible natural resources

  • The resources which are never-ending and will not be depleted even after continuous usage are inexhaustible resources.
  • These resources are available in large quantities in air.
  • Sunlight and air are some examples.

Exhaustible resources:

exhaustible resources

  • The resources which are present in a limited amount and can be depleted after continuous usage are said to be exhaustible resources.
  • Overexploitation of exhaustible resources can lead to a higher rate of depletion.
  • Coal, petroleum and minerals are some examples of exhaustible resources.

Fossil fuels

fossil fuels

  • Dead and decayed remains of organisms which are more than 10,000 years old are called fossils.
  • Those substances which bums in air to produce energy without releasing harmful gases in large quantities are said to be fuels.
  • The formation of coal and petroleum possess the same reason. So these are said to be fossil fuels.

Calorific value of fuels:

  • The amount of heat liberated by complete burning of a unit mass or volume of fuel is said to be calorific value of the fuel.
  • To find out the calorific value of liquid or gaseous fuels, volume of fuel is considered while for solid fuels mass of fuel is considered.
  • Its unit is KJ/Kg.
  • Calorific value = \(\frac{Amount\:of \:liberated\: heat\: energy}{Total\:mass\:of\:fuel}\)

Features of ideal fuel:

  • Possess high calorific values.
  • Pollution free by not releasing any harmful gases
  • Cost-effective
  • Easily available
  • Easy to handle and transport and store.
  • Moderate ignition temperature
  • Rate of combustion should also be moderate.



  • It is quite hard and stone-like substance.
  • Coal appears black in colour.
  • It is of great use since times.
  • We use coal to heat a substance, cook food, run trains, in thermal power plants to produce electricity etc.

History of coal:

  • Millions of years ago on the earth there were only forest and grasslands.
  • Due to natural calamities, like floods, earthquakes the forests are buried under the soil.
  • Above the dead plants, layers of soil were formed.
  • As dead plants went deeper and deeper under the soil they got compressed.
  • The excess temperature and pressure produced on these materials converted it into coal.


  • The process of conversion of dead plants vegetation into coal is said to be carbonization.
  • Coal is mainly composed of carbon as on burning it releases carbon and its product.

Uses of coal

  • Earlier it was used as fuel in steam engine.
  • Thermal power plants use coal as fuel.
  • Some households, dhabas still uses coal as the kitchen fuel.

Products of coal:

Some of the widely used products of coal are:


  • Coke is the form of coal which is hard, porous and black in colour.
  • It is said to be the purest form of carbon.
  • It is used in extraction of metals and manufacturing of steel.

Coal Tar:

  • It is thick black liquid.
  • It bears unpleasant smell.
  • It is mixture of different substances.
  • Synthetic dyes, explosives, drugs, perfumes, plastics, paints, roofing materials, etc. are prepared from Coal tar.
  • Naphthalene balls for keeping insects away are also made from Coal tar.
  • A form of coal tar i.e. bitumen is used for metalling of roads.

Coal Gas:

  • Coal gas is mid material obtained between the process of obtaining coke from coal.
  • It is used as fuel in many industries which are situated near coal mines.
  • Earlier coal gas was used in London for lightning process but now it is used for heating purpose rather than lightning process.


petroleum types and uses

  • Petroleum is a dark oily liquid.
  • It is a mixture of various substances, like petroleum gas, diesel, petrol, paraffin wax, lubricating oil, etc.
  • Earlier several organisms lived in sea.
  • When they died their remains got settled at the bottom of the sea.
  • The layers of clay deposited over it.
  • In the absence of air with excess of temperature and pressure converted them to petroleum.

Refining of petroleum:

  • The process of separating its constituents (petrol, diesel, wax etc.) from petroleum is said to be refining.
  • Refining is done in petroleum refinery.
  • Petrochemicals are useful substances are obtained from petroleum and natural gas.
  • Detergents, polythene, fibres (nylon, polyester, acrylic etc.) and other artificial plastics are manufactured from petrochemicals.
  • Due to the great commercial importance of petroleum, these are termed as “black gold”.

Uses of petroleum and its constituents:

The uses of different constituent of petroleum are listed below;

  • Liquid Petroleum Gas (LPG): It is the main source of fuel in household and in some industries.
  • Petrol: Automobiles uses it as a fuel and also used in dry cleaning.
  • Diesel: It is used as a fuel for heavy machinery like rail engine, factories machines etc.
  • Kerosene: It is mainly used in lamps and for jet aircraft.
  • Paraffin wax: It is used in ointments, candles, cosmetics, Vaseline etc.
  • Lubricating oil: For lubricating machinery lubricating oil is used.
  • Bitumen: Used in metalling roads.

Natural gas:

natural gas

  • Millions of years ago natural gas was formed.
  • Microscopic sea plants and animals died & got buried under the mud.
  • Under anaerobic conditions, these plants and animals changed to natural gas.
  • Natural gas mainly contains methane with 85% composition.
  • 10% of it is ethane and 3% butane is present in it.
  • When Natural Gas is compressed at high pressure then gets converted into compressed natural gases.
  • It is ideal fuel with a calorific value of 55Ktj/g.

Uses of Natural gas:

  • It is also used for power generation.
  • Because of its less pollution measure, it is used in vehicle as fuel.
  • It can easily be transported from one place to another through pipeline.
  • It is also used as the beginning material for manufacturing of fertilizers.

Conservation of natural resources:

  • It took millions of years for the dead organisms to get converted into coal, petroleum or natural gas.
  • We have limited known resources.
  • These resources are exhaustible.
  • It is our responsibility to use them as less as possible.
  • To fulfil our energy requirement, we must look for alternative sources of energy such as solar energy, tidal energy, wind energy, etc.
  • Limited usage of these resources will save our earth from pollution, which will decrease the risk of Global warming.
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