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NCERT Solutions for Class 8th Science

 

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Chapter 5. Coal And Petroleum

Text Book Exercise

 

 

 

Exercise


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

Answer : The advantages of using CNG and LPG are as follows :

(i) These are clener fuels. 

(ii) These are low coct fuels.

(iii) These are available easily.

(iv) These can be used directly for buring in homes and factories where it can supplied through pipes. 

Q2. Name the petroleum product used for surfacing of roads.

Answer : These days bitumen, a petroleum product is used for surfacing the roads in place of coaltar. 

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

Answer: About 300 million years ago, earth was having dense forests in low lying wet land areas. Due to earthquakes and volcanic erruptions, these forests got buried under he soil. As more soil deposited over them, they were compressed. The temperature also raised as they sank deeper and deeper. Due to high temperature and lack of oxygen dead plants inside the earth got slowly converted to coal. As coal contains manily carbon, the slow process of conversion of dead vegetation into coal is called carbonisation.  

Q4. 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 vehicle is .

Answer : (a) coal, petroleum, natural gas. 

 (b) refining.

 (c) CNG (compressed natural gas).

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