NCERT Solutions for Class 8 Science Chapter 3 Coal and Petroleum

NCERT Solutions for Class 8 Science Chapter 3 Coal and Petroleum

Question 1:
Make a list of various materials used by us in daily life and classify them as natural and man-made materials (Refer to Activity 5.1).
Answer

Question 2:
Does this list include air, water, soil and minerals?
Answer:
Yes, this list contains, air, water, soil and minerals.

Question 3:
Can we use all our natural resources forever?
Answer
No, we cannot use all our natural resources forever, because these are going to exhaust one day.

Question 4:
Can air, water and soil he exhausted by human activities?
Answer
No, these can not be exhausted at all.

Question 5:
Is water a limit less source?
Answer
Yes, water is a limitless source, but by unwise use and cutting of trees, sources of water can be finished.

Question 6:
What are the advantages of using CNG and LPG as fuels?
Answer
The advantages of using CNG and LPG:
        (i) CNG and LPG are clean fuels.
        (ii) Their cost is low.
        (iii) They can he used directly for burning.
        (iv) They are easily available.
        (v) They do not produce pollution.

Question 7:
Name the petroleum product used for surfacing of roads.
Answer
Bitumen is the petroleum product which is used for surfacing of roads these days

Question 8:
Describe how coal is formed from dead vegetation. What is this process called?
Answer
About 300 million years ago the earth had dense forest in low lying wetland areas. Due to various natural processes, like flooding and earthquakes, these forests got buried under the soil. The soil eposits layer by layer over them, they were compressed. Under high temperature and pressure the plants got converted to coal slowly. This process is called carbonisation.

Question 9:
Fill in the blanks.

a.    Fossil fuels are ______, _____________ and ____________. (Imp)
b.    Process of separation of different constituents from petroleum is
called _______.
c.     Least polluting fuel for vehicles is__________.
d.    Forests and coal are _________ natural resources. (imp.)

Answer
(a) Coal, Petroleum and Natural gas
(b) Refining
(c) Compressed Natural Gas (CNG).
(d) 

Question 10:
True/False.
(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) Coaltar is a mixture of various substances.
(e) Kerosene is not a fossil fuel.
Answer
(a) False        (b) False        (c) True        (d) True        (E) False.

Question 11:
Explain why fossil fuels are exhaustible natural resources.
Answer
Fossil fuels are present in limited quantity in the nature. They can be exhausted by human activities. So fossil fuels are called exhaustible natural resources.

Question 12:
Describe characteristics and uses of coke.
Answer
Characteristic of coke:
        (i) Coke is tough.
        (ii) It is porous and black substance.
        (iii) It is an almost pure form of carbon.

Uses: 
Coke is used in the manufacture of steel and in the extraction of many metals.

Question 13:
Explain the process of formation of petroleum.
Answer
Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea. These bodies got covered with layers of sand and clay. Over millions of years, in the absence of air, and under high temperature and pressure the dead bodies are converted into petroleum and natural gas.

Question 14:
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 years on the y-axis and the year on x-axis.