NCERT solution for class 8 // Science// Chapter 5 - Coal and Petroleum

 NCERT solution > class 8 science  > Chapter 5 - Coal and Petroleum 

NCERT solution for class 8 // Science// Chapter 5 - Coal and Petroleum

Chapter 5 - Coal and Petroleum

Exercise

Q1. What are the advantages of using CNG and LPG as fuels. 

Answer  

LPG and CNG both produce less quantity of pollution they have following advantages 

Advantages of using CNG as a fuel 

  • CNG burn easily with smokeless flame and it is a clean fuel 
  • CNG is used as a fuel for vehicle because it is less polluting
  • It is also used as a fuel in the thermal power station for generating electricity 
  • It can be used in home and factories for directly burning process 

Advantages of LPG as a fuel 

  • LPG does not leave behind any solid residue after burning
  • It does not produce any poisonous gases during burning
  • It has high calorific  value .
  • It create a smokeless flame and it is clean fuel.

Q2. Name the petroleum product used for surfacing of roads 

Answer  

Bitumen is used for surfacing of roads

Q3. Describe how coal is formed from dead vegetation what is this process called? 

Answer  

Coal is formed from dead vegetation about 300 million years ago the earth had dence forest due to natural disaster like flooding , earthquake, landsliding the forest got buried under the soil due to formation of new soil they undergo deep down the earth and die to high pressure and temperature  slowly plants get converted into coal this is a very slow process of dead vegetation into coal is called carbonisation 

Q4. Fill in the blanks 

a ) Fossils fuels are coal , petroleum and natural gas 

b) Process of separation of different constitutes from petroleum is called refining 

c) Least polluting fuel for vehicle is CNG 

Q5 . True false against the following statement 

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 substance 

e) Kerosene is not a fossil fuel 

Answer 

a) False

 b) False 

c) True 

d) True

d) False 

Q6. Explain why fossil fuels are exhaustible natural resources 

Answer 

Fossils fuel are made by the action of heat and pressure on that remains of dead of vegetation and animal it required millions of the years for preparation  and it is limited source but the rate at which we are using them is very fast as compared to rate of its formation therefore  fossil fuel are exhaustible natural resources 

Q7. Describe characteristics and uses of coke

Answer 

Coke is obtained by the destructive distillation of coal it is porous Black substance and it has following characteristics 

  • Coke is a pure form of carbon 
  • It burns almost with no smoke 
  • It does not conduct heat and electricity 

Uses of coke 

  • It is used for the manufacturing of Steel 
  • Coke is used in the extraction of metals from its ore  

Q8 . Explain the process of formation of petroleum 

Answer 

  • Petroleum formation takes place inside the sea it is the remains of sea organisms 
  • When the sea organism divides they got buried at the bottom of sea 
  • After passage of time the body is got covered with mud 
  • Due to high pressure and temperature they got married lower and lower in the earth 
  • Due to the action of temperature pressure and bacteria in absence of air that decomposed very slowly and forming a petroleum 

Q9. The following table shows the total power shortage in India from 1991 1997 show the data in the form of a graph plot shortage percentage for the years on the y-axis and year on the x-axis 

Sr No

Year

Shortage

%

1

1991

7.9

2

1992

7.8

3

1993

8.3

4

1994

7.4

5

1995

7.1

6

1996

9.2

7

 1997

11.5

Answer 



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