Coal and Petroleum (Chemistry) Class 8 - NCERT Questions

Q 1.

What are the advantages of using CNG and LPG as fuels?


The advantages of using CNG and LPG as fuels are following:
(i) CNG and LPG both are clean fuels.
(ii) Their cost is low.
(iii) They burn with a blue flame without any smoke. Thus they do not blacken utensils or pollute air.
(iv) They are very easy to handle, ignite and to put off.
(v) They have a very high calorific values.
(vi) They are easily available.

Q 2.

Name the petroleum product used for surfacing of roads.


Bitumen is the petroleum product used for surfacing of roads.

Q 3.

Describe how coal is formed from dead vegetation. What is this process called?


About 300 million years ago, there were dense forests in low-lying wetland areas on the earth. As the trees died, they got covered with sand and mud. More trees grew on this sand and mud. When these died, they too got covered. Sometimes earthquake and volcanoes buried entire forests deep down in the earth. The high temperature and high pressure inside the earth slowly converted the buried vegetation into coal. A coal contains mainly carbon. Thus, this slow process of conversion of wood into coal is called carbonization.

Q 4.

Fill in the blanks.
(A) Fossil fuels are ............, .............. and ............... .
(B) Process of separation of different constituents from petroleum is called ............... .
(C) Least polluting fuel for vehicles is ............. .


(A) coal, petroleum, natural gas
(B) refining

Q 5.

Tick true/false against the following statements.
(A) Fossil fuels can be made in the laboratory.
(B) CNG is more polluting fuel than petrol.
(C) Coke is almost pure form of carbon.
(D) Coal tar is a mixture of various substances.
(E) Kerosene is not a fossil fuel.


(A) False
(B) False
(C) True
(D) True
(E) False

Q 6.

Explain why fossil fuels are exhaustible natural resources.


Fossil fuels are limited in the nature and can be exhausted very soon by human activities. So fossil fuels are called exhaustible natural resources.

Q 7.

Describe characteristics and uses of coke.


Characteristics of coke:
(i) It is an almost pure form of carbon.
(ii) It is porous and black substance.
(iii) It is a bad conductor of heat and electricity.
(iv) It is tough.
Uses of coke :
(i) It burns easily and does not produce any smoke.
(ii) It is a very good reducing agent.
(iii) It is used in the manufacture of gaseous fuel. e.g. producer gas (N2 + CO) and water gas (H2 + CO).
(iv) It is used in the manufacture of steel and in the extraction of many metals.

Q 8.

Explain the process of formation of petroleum.


Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.

Q 9.

The following table shows the total power shortage in India from 1991-1997. Show the data in the form of graph. Plot shortage percentage for the year on the y-axis and the year on x-axis.