NCERT Solutions for Class 8th Science Chapter 2 Coal and Petroleum Questions and answers Based on the latest syllabus of CBSE and JKBOSE
Coal and Petroleum
Exercises
1. What are the advantages of using CNG and LPG as fuels?
Answer: The advantages of using CNG and LPG as fuels include:
- They produce less pollution compared to petrol and diesel.
- They are more economical.
- They have a higher calorific value.
- They cause less damage to the environment and human health.
2. Name the petroleum product used for surfacing of roads.
Answer: The petroleum product used for surfacing of roads is bitumen.
3. Describe how coal is formed from dead vegetation. What is this process called?
Answer: Coal is formed from dead vegetation when it is buried under layers of soil and subjected to high pressure and temperature over millions of years. This process is called carbonization.
4. Fill in the blanks:
- (a) Fossil fuels are coal, petroleum, and natural gas.
- (b) Process of separation of different constituents from petroleum is called refining.
- (c) Least polluting fuel for vehicle is CNG.
5. Tick True/False against the following statements:
(a) Fossil fuels can be made in the laboratory.
Answer: False
(b) CNG is more polluting fuel than petrol.
Answer: False
(c) Coke is almost pure form of carbon.
Answer: True
(d) Coal tar is a mixture of various substances.
Answer: True
(e) Kerosene is not a fossil fuel.
Answer: False
6. Explain why fossil fuels are exhaustible natural resources?
Answer: Fossil fuels are exhaustible natural resources because they are formed over millions of years from the remains of dead plants and animals. Their formation takes a long time, and the rate at which we are using them is much faster than the rate at which they are being formed. Once depleted, they cannot be replaced within a human lifetime.
7. Describe characteristics and uses of coke.
Answer: Coke is a tough, porous, and black substance. It is almost pure form of carbon. Uses of coke include:
- It is used as a fuel.
- It is used in the extraction of metals.
- It is used in the manufacture of steel.
8. Explain the process of formation of petroleum.
Answer: Petroleum is formed from the remains of tiny marine organisms that were buried under the ocean floor millions of years ago. As these organisms got buried deeper, they were subjected to high pressure and temperature, which transformed them into petroleum. This process is called petroleum formation.
9. 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.
Answer:
- Year: 1991, Shortage (%): 7.9
- Year: 1992, Shortage (%): 7.8
- Year: 1993, Shortage (%): 8.3
- Year: 1994, Shortage (%): 7.4
- Year: 1995, Shortage (%): 7.1
- Year: 1996, Shortage (%): 9.2
- Year: 1997, Shortage (%): 11.5
(Students are required to plot this data on a graph as part of their exercise).
10. What are exhaustible natural resources? Give examples.
Answer: Exhaustible natural resources are those resources that are available in limited quantities and can be exhausted by human activities. Examples include coal, petroleum, and natural gas.
11. What are inexhaustible natural resources? Give examples.
Answer: Inexhaustible natural resources are those resources that are abundant in nature and cannot be exhausted by human activities. Examples include sunlight, air, and water.
12. Why is natural gas called a clean fuel?
Answer: Natural gas is called a clean fuel because it burns completely, leaving no residue. It produces fewer pollutants and greenhouse gases compared to other fossil fuels like coal and petroleum.
13. What are the uses of coal?
Answer: Uses of coal include:
- It is used as a fuel in homes and industries.
- It is used in the generation of electricity in thermal power plants.
- It is used in the manufacture of steel.
- It is used in the production of various chemicals.
Extended Learning — Activities and Projects
1. Get an outline map of India. Mark the places in the map where coal, petroleum and natural gas are found. Show the places where petroleum refineries are situated.
Answer: This activity involves marking the locations of coal mines, petroleum fields, natural gas reserves, and petroleum refineries on a map of India.
2. Choose any five families of your neighbourhood. Enquire whether their energy consumption (coal, gas, electricity, petrol, kerosene) has increased or decreased in the last five years. Enquire also about the measures they adopt to conserve energy.
Answer: This activity involves surveying five families about their energy consumption patterns and the conservation measures they adopt.
3. Find out the location of major thermal power plants in India. What could be the reasons for their being located at those places?
Answer: This activity involves researching and marking the locations of major thermal power plants in India and understanding the reasons for their specific locations, such as proximity to coal mines, water sources, and population centers.
4. Find out the location of major power projects in J&K. What could be the reasons for their being located at those places?
Answer: This activity involves researching and marking the locations of major power projects in Jammu & Kashmir and understanding the reasons for their specific locations, such as availability of water resources for hydroelectric projects and topographical advantages.
