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energy can be utilized either by burning it or by ago, the earth had dense forests and low-lying
altering it to another form. wetland area.

Fossil Fuels : Fuels obtained or formed from
the remains of dead and decaying plants and Floods came, leading to the submergement
animals are called fossil fuels. Examples of of these forests.
fossil fuels include coal and petroleum.

Coal : Coal is a hard stone. It is black or brown
Thereafter, layers of soil got deposited over
in colour. It is highly combustible. Coal consists
it.
of carbon as the main component along with
minor quantities of sulphur, hydrogen, oxygen
and nitrogen. This generated both heat and pressure on
dead submerged vegetation.
In air, coal combines with oxygen to form
carbon dioxide.

Occurrence of Coal : Coal is “mineral fossilized Heat and pressure thus converted dead
carbon”. Coal is present in coal beds or coal vegetation to the carbonized fuel called coal.
seams deep under the surface of the earth. Process of formation of coal is called

Formation of Coal : About 300 million years carbonization. The age during which coal
formation took place was the carboniferous
age.

Dead Plants

Coal formation

Types of Coal : Depending upon the amount of (b) Lignite : It is the coal of lowest quality. It is
coal content, coal can be of the following also called as brown coal or rosebud coal. It
types: has carbon content of about 20-35% and
(a) Peat : It is the precursor of coal. Peat is ash content of 6-19%, rest of the

actually an accumulated partly composition of lignite is formed by
decomposed vegetation. moisture, which is about 66%.

Peat Lignite

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