# TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VIII SCIENCE-Chapter-5 COAL AND PETROLEUM

Exercise

1) What are the advantages of using CNG and LPG as
fuels?
(i) They can be burnt directly.
(ii) They can be transported easily
through pipe lines.
(iii) They are clean fuels and do not
give smoke when burnt.
(iv) They give a lot of heat energy
when burnt.
2) Name the petroleum product used for surfacing of
.
3) Describe how coal is formed from dead vegetation. What
is this process
called?

years ago the earth had dense forests in low lying wetland areas. Due to
natural processes, like earth quakes, flooding, these forests got
buried under the soil,
rocks and other land masses. With the passage of time, as more soil deposited over them, they were compressed. The temperature
also rose as they sank deeper and deeper.
Under high pressure and high temperature, dead plants got slowly converted to
coal. As coal contains mainly carbon, the slow process of conversion of dead
vegetation into coal is called carbonisation. Since it was formed from the
remains of vegetation, coal is also called a fossil fuel.
4) Fill in the blanks:
(a) Fossil fuels are –Coal–, –Petroleum– and –Natural
gas–.
(b) Process of separation of different constituents from
petroleum is called –Refining–.
(c) Least polluting fuel for vehicle is –CNG–
5) Tick True/False against the following statements:
(a) Fossil fuels can be made in the
laboratory. ( F)
(b) CNG is more polluting fuel than
petrol. ( F)
(c) Coke is almost pure form of
carbon. ( T )
(d) Coal tar is a mixture of various
substances. ( T )
(e) Kerosene is not a fossil fuel.
(F)
6) Explain why fossil fuels are exhaustible natural
resources.
natural resources, as
limited fossil fuels reserves like coal, petroleum, natural
gas are being depleted very fast by human activities like rapid urbanization,
industrialization and transportation.
7) Describe characteristics and uses of coke.
(i) Tough
(ii) Porous
(iii) Black in colour
Uses of coke:
(i) In manufacture of steel.
(ii) In the extraction of metals (as a reducing agent).
Coke is used in the homes for cooking, heating and in
industries, for manufacturing of steel and extraction of many metals. Earlier
it was also used in steam engines for rail transportation. It is also used in
thermal power plants to produce
electricity.
8) Explain the process of formation of petroleum.