Science STD 8 Chapter 3: Coal and Petroleum - Exercises
1. What are the advantages of using CNG and LPG as fuels?
The advantages of using CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas) as fuels are that they are less polluting, cleaner fuels that can be used directly for burning in homes and factories through a network of pipes. They are also easy to transport and store.
2. Name the petroleum product used for surfacing of roads.
The petroleum product used for surfacing roads is bitumen.
3. Describe how coal is formed from dead vegetation. What is this process called?
About 300 million years ago, the Earth had dense forests in low-lying wetland areas. Due to natural processes like flooding, these forests were buried under the soil. As more soil was deposited over them, they were compressed. Under high pressure and high temperature, the dead vegetation slowly got converted into coal. This slow process of converting dead vegetation into coal is called **carbonisation**.
4. Fill in the blanks.
- (a) Fossil fuels are coal and petroleum.
- (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. (T/F)
F
- (b) CNG is more polluting fuel than petrol. (T/F)
F
- (c) Coke is 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
6. Explain why fossil fuels are exhaustible natural resources.
Fossil fuels are exhaustible natural resources because the amount of these resources in nature is limited. They were formed over millions of years from the dead remains of living organisms. Once consumed, they cannot be replenished quickly, and their known reserves are estimated to last only a few hundred years. Continued human consumption will eventually lead to their complete exhaustion.
7. Describe characteristics and uses of coke.
Coke is a tough, porous, and black substance that is an almost pure form of carbon. It is obtained by processing coal in an industry. Coke is used in the manufacture of steel and in the extraction of many metals. It is a highly useful product due to its pure carbon content.
8. Explain the process of formation of petroleum.
Petroleum was formed from organisms that lived in the sea. As these organisms died, their bodies settled at the bottom of the sea and were covered by layers of sand and clay. Over millions of years, due to the absence of air and under high temperature and high pressure, these dead organisms slowly transformed into petroleum and natural gas. This process is similar to the formation of coal but occurs with marine organisms.
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.
A graph would be plotted with the years (1991, 1992, 1993, 1994, 1995, 1996, 1997) on the X-axis and the power shortage percentage (from 7.1 to 11.5) on the Y-axis. The data points would be marked and connected to create a line graph showing the trend of power shortage over the years.
Suggested 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.
Outline: This activity involves using a map of India to mark key locations of fossil fuel resources. You would identify states like Assam, Gujarat, and Maharashtra for oil; Tripura, Rajasthan, and the Krishna Godavari delta for natural gas; and states like Jharkhand, Chhattisgarh, and Odisha for coal. You would also mark the locations of major petroleum refineries, providing a clear visual representation of India's energy resources.
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.
Outline: This project is a social survey to understand energy consumption patterns and conservation efforts. By interviewing five families, you would gather data on their use of various fuels over the past five years. You would also learn about practical conservation methods they use, such as switching to energy-efficient appliances, using public transport, or adopting solar energy. This activity promotes awareness of energy conservation in daily life.
3. Find out the location of major thermal power plants in India. What could be the reasons for their being located at those places?
Outline: This project involves researching the location of thermal power plants. You would discover that these plants are often located near coal mines or water sources. The reasons for this are that thermal power plants use coal as their primary fuel, and transporting coal is expensive. Locating the plants near the source of fuel (coal) or a large water body (for cooling purposes) makes the process more economical and efficient.