Science Class 8-Chapter 5-Coal and Petroleum- NCERT Exercise Solution ( Question-Answer) is provided below.
Exercise with Answer –
Q.1 What are the advantages of using CNG and LPG as fuels?
Answer: Advantages of using CNG and LPG as fuels are-
- CNG and LPG are less polluting fuels.
- CNG and LPG are clean fuels because they not release smoke when burnt.
- After burning they don’t leave ash.
- They can be used directly for burning.
- CNG and LPG can be transported through pipelines.
- They do not produce harmful gas, they burn with a smokeless flame.
- Easy to burn LPG and CNG.
- They give a lot of heat energy when burnt.
Q2. Name the petroleum product used for surfacing of roads.
Anwer: Bitumen is a petroleum product used for surfacing of roads.
3. Describe how coal is formed from dead vegetation. What is the process called?
Answer: Millions of years ago dense forests got buried under the soil and rock due to natural processes like flooding, earthquake, etc. These forests got buried under the soil. The soil deposits layer by layer over them, they were compressed. Under high temperature and pressure and lack of air, the plants got slowly converted to coal.
The slow process of conversion of dead vegetation into coal is called carbonisation.
4. Fill in the blanks.✍️
(a) Fossil fuels are ____________, ___________and _____________.
Answer: coal, petroleum and natural gas
(b) Process of separation of different constituents from petroleum is called __________.
Answer: refining
(c) Least polluting fuel for vehicle is ______________.
Answer: CNG
Q5. Tick True/ False against the following statements.
(a) Fossil fuels can be made in the laboratory. (T/F) F (❌)
(b) CNG is more polluting fuel than petrol. (T/F) F (❌)
(c) Coke is the almost pure form of carbon. (T/F) T (✔️)
(d) Coal tar is a mixture of various substances. (T/F) T (✔️)
(e) Kerosene is not a fossil fuel. (T/F) F (❌)
Q6. Explain why fossil fuels are exhaustible natural resources.
Answer: Fossil fuels are exhaustible natural resources because they are limited in nature and cannot be prepared in the laboratory.
It takes millions of years to be formed.
Q7. Describe the characteristics and uses of coke.
Answer: Characteristic of coke–
- It is a pure form of carbon.
- It is tough, porous and black substance.
- It burns without producing any smoke.
Uses of coke-
It is used in the manufacture of steel and in the extraction of many metals.
8. Explain the process of the formation of petroleum.
Answer: Petroleum is formed by dead aquatic animals and plants that get buried in sea millions of years ago. They got covered by a layer of sand and clay. Due to lack of air and due to high temperature and high pressure, these dead organisms get converted into petroleum and natural gas.
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 the year on the X-axis.
| S. No. | Year | Shortage(%) |
| 1
2 3 4 5 6 7 | 1991
1992 1993 1994 1995 1996 1997 | 7.9
7.8 8.3 7.4 7.1 9.2 11.5 |
Answer:
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