5. Coal And Petroleum Science class 8 in English Medium ncert book solutions 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).

5. Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory. (T/F)

(b) CNG is more polluting fuel than petrol. (T/F)

(c) Coke is almost pure form of carbon. (T/F)

(d) Coal tar is a mixture of various substances. (T/F)

(e) Kerosene is not a fossil fuel. (T/F)

Answer:

(a)-(f) (b)-(f) (c)-(t) (d)-(t) (e)-(f)

6. Explain why fossil fuels are exhaustible natural resources.

Answer:

Fossil fuels are present in nature is limited quantity and are being exhausted abundantly by us. That is why fossil fuels are called exhaustable natural resourses.

7. Describe characteristics and uses of coke. 

Answer:

Coke is a tough, porous and substance. It is almost pure form of carbon. It is use vin the manufacture of steel and in the extraction of many metals.

8. Explain the formation of pertroleum.

Answer: 

petroleum is formed from organisms living in the sea. When these organisms died, their bodies seettled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, they were transformed into petroleum and natural gas under the absence of air and presence og high temperature and pressure.

Q9. The following table shows the total power shortage in india from 1991 - 1997. show the data in the from of a graph. Plot shortage percentage for the years on the Y - axis and the year on the X - axis.

Answer: