2. Coal
 Coal is one of the most commonly used by humans today. It is
obtained by mining . It is black or brownish-black rock-like
substance made up of carbon, hydrogen, oxygen, nitrogen,
and varying amounts of sulphur.
 Coal is formed by the slow decomposition of organic plant
materials that have been subjected to heat and pressure in the
absence of oxygen for about 300 million years. Coal primarily
contains carbon. Hence, the slow process of conversion of
dead vegetation into coal is called carbonization.
 When heated in air, coal burns and produces mainly carbon-
dioxide gas along with heat energy. Coal is mainly used to
generate electricity in power stations. It is the world’s main
source of energy for the production of electricity.

3. Formation Of Coal.
 Millions of years ago, Earth was covered with dense
swampy forests. The plants that perished fell into swamp
waters while new plants grew to take their places.
Overtime, the fallen plants got covered by layers of mud,
sand, and dirt. The new plants that took the place of the
fallen plants also perished and fell to form another layer in
the swamp water. This cycle continued, and after millions
of years, many layers formed one on top of the other
 The weight of the top layers of plant matter together with
extreme heat and pressure under the surface of the earth
produced chemical and physical change to convert the
plant matter into black, hard, rock-like substance coal.

4. Types Of Coal.
There are four main types
of coal depending on the
varying percentage if
carbon content – peat,
lignite, bituminous, and
anthracite.

5. Destructive Distillation of Coal.
It is a process of heating a complex
substance, such as coal, in a limited
supply of air so that it breaks down
to form simpler substances. In this
process, coal is heated to 1000*C in
the absence of air to obtain
different useful components such as
coke, coal tar, coal gas.

6. Coke.
It is a porous, black
substance that is left behind
as a residue when coal is
subjected to destructive
distillation. It is an almost
pure form of carbon,
containing 90% carbon.

7. Coal Tar.
It is a thick, black liquid with
an unpleasant smell. It is a
complex organic compound
and can be separated to
many important simpler
compounds for further use.

8. Coal Gas.
Coal gas is a mixture of hydrogen,
methane, carbon monoxide, and
other gases. It was earlier used as a
domestic-lightning fuel before
natural gas came into use. It is
presently used as a fuel in some
industries located near the coal
processing plants.

9. Uses Of Coal.
 Coal has numerous uses, some of which are listed as follows:
 Coal is widely used as a fuel because it burns easily and releases
high amount of heat energy.
 Other fuels such as coal gas, coal tar, synthesis petrol, methane,
and coke are derived from coal.
 Coke is used in the manufacture of steel. It is largely used as a
reducing agent in the extraction of metals from their ores.
 Coke is also used as a fuel and is preferred over coal since it burns
without smoke.
 Coal tar is used in the manufacture of many useful organic
compounds such as synthetic dyes, drugs, pesticides,
naphthalene balls, explosives, perfumes, plastics, paints,
photographic materials, roofing materials, and so on.

10. Petroleum.
 Petrol is also an important fossil fuel. Petroleum is also
called crude oil. It is found locked in impervious rocks
deep below the earth’s crust. Crude oil is a smelly, dark-
colored liquid, which is a mixture of various hydrocarbons
(compounds made of only carbon and hydrogen) such as
natural gas ,gasoline, kerosene, asphalt, and fuel oil.
 Products of petroleum such as petrol, diesel, and jet fuel
are used to run cars, trucks, aircrafts, ships, and other
vehicles. It is hard to imagine our life without synthetic
fibers, wax, plastics, fertilizers, lubricants, and many
more – all of which are available to us because of
petroleum.