Lakhmir Singh Class 8 Science Solutions
Chapter 5: Coal and Petroleum - Complete Solutions
Updated on June 19, 2025
Very Short Answer Type Questions
1. Name three useful products of coal.
Answer: Coke, coal tar, coal gas.
Explanation: These are obtained by processing coal through destructive distillation, each used in industries, chemicals, or as fuels.
2. Which product of coal is used as a reducing agent in the extraction of metals?
Answer: Coke.
Explanation: Coke, nearly pure carbon, reduces metal oxides to pure metals in processes like iron extraction in a blast furnace.
3. Name the process by which plant material buried deep under the earth was slowly converted into coal.
Answer: Carbonisation.
Explanation: Over millions of years, heat and pressure transformed buried plant matter into coal in the absence of air.
4. Name the product of coal which is a thick black liquid having an unpleasant smell.
Answer: Coal tar.
Explanation: Coal tar, a byproduct of coal processing, is a viscous liquid used to produce chemicals like naphthalene.
5. Name any five substances used in everyday life which are manufactured starting from the products of coal tar.
Answer: Synthetic fibres, plastics, perfumes, paints, pesticides.
Explanation: Coal tar provides chemicals like benzene, used to make products such as nylon, plastic containers, and insect repellents.
6. Name an important source from which naphthalene balls are obtained.
Answer: Coal tar.
Explanation: Naphthalene, used for mothballs, is extracted from coal tar through distillation.
7. Which substance is used for metalling the roads these days in place of coal tar?
Answer: Bitumen.
Explanation: Bitumen, a petroleum product, is durable and widely used for road surfacing, replacing coal tar.
8. Name the most common fuel used in light motor vehicles.
Answer: Petrol.
Explanation: Petrol (gasoline) is efficient for cars and motorcycles due to its combustion properties.
9. Name the fuel which is used in jet aircraft engines.
Answer: Kerosene.
Explanation: A special grade of kerosene, called aviation fuel, powers jet engines due to its high energy content.
10. Name the petroleum product used to drive heavy vehicles.
Answer: Diesel.
Explanation: Diesel provides more power for heavy vehicles like trucks and buses.
11. Name the petroleum product commonly used for electric generators.
Answer: Diesel.
Explanation: Diesel’s high energy output makes it ideal for powering generators.
12. What is the full form of LPG?
Answer: Liquefied Petroleum Gas.
Explanation: LPG is a mixture of propane and butane, stored as a liquid under pressure for cooking and heating.
13. Is it possible to extract petroleum from under the sea bed?
Answer: Yes.
Explanation: Offshore drilling rigs extract petroleum from seabed reserves, like in Mumbai High.
14. What is the full form of CNG?
Answer: Compressed Natural Gas.
Explanation: CNG is natural gas compressed for use as a cleaner vehicle fuel.
15. Name the major component of natural gas.
Answer: Methane.
Explanation: Methane (about 95%) makes natural gas a clean-burning fuel.
16. Name any two places in India where natural gas is found.
Answer: Vadodara, Mumbai high.
Explanation: These regions have natural gas reserves, often alongside petroleum.
17. Name a fossil fuel other than coal and petroleum.
Answer: Natural gas.
Explanation: Natural gas, formed from organic remains, is a key fossil fuel for energy.
18. Name two places in India where coal is found.
Answer: Jharkhand , West Bengal.
Explanation: Major coal fields like Jharia (Bihar) and Raniganj (West Bengal) are located here.
19. Name the petroleum product used for surfacing of roads.
Answer: Bitumen.
Explanation: Bitumen’s sticky, durable nature makes it ideal for paving roads.
20. Name any four places in India where petroleum is found.
Answer: Assam, Gujarat, Mumbai High, Godavari River basins.
Explanation: These are major petroleum-producing regions, with Mumbai High being a key offshore field.
21. Write the full form of PCRA.
Answer: Petroleum Conservation Research Association.
Explanation: PCRA promotes fuel conservation and efficient energy use in India.
22. State whether the following statements are true or false:
- a. Coke is almost pure form of carbon. True (Coke is nearly pure carbon after removing impurities).
- b. Coal tar is a mixture of various substances. True (Contains chemicals like benzene).
- c. Kerosene is not a fossil fuel. False (Kerosene is a petroleum product).
- d. CNG is more polluting than petrol. False (CNG burns cleaner).
- e. Fossil fuels can be made in the laboratory. False (They form naturally over millions of years).
23. Fill in the following blanks with suitable words:
- a. Fossil fuels are coal, petroleum, natural gas.
- b. Coal contains mainly carbon.
- c. The slow process of conversion of dead vegetation into coal is called carbonisation.
- d. The process of separation of different constituents from petroleum is called refining.
- e. The least polluting fuel for vehicles is CNG.
- f. The burning of fossil fuels causes air pollution and also leads to global warming.
Explanation: These terms describe fossil fuels, their properties, formation, processing, and environmental impacts.
Short Answer Type Questions
24. Explain why fossil fuels are exhaustible natural resources.
Answer: Fossil fuels (coal, petroleum, natural gas) are formed over millions of years from ancient organic remains. Their slow formation and rapid consumption make them exhaustible.
Explanation: Since they cannot be replenished on a human timescale, they will eventually run out.
25. Describe how coal was formed. What is this process called?
Answer: About 300 million years ago, large land plants and trees died and were buried. Heat, pressure, and bacteria transformed them into coal via carbonisation.
Explanation: In the absence of air, geological forces converted plant matter into carbon-rich coal over millions of years.
26. What happens when coal is heated in air? State the uses of coal.
Answer: Coal burns, producing carbon dioxide and heat.
Uses: Fuel in homes/industries, electricity generation in thermal power plants.
Explanation: Burning coal releases energy but causes pollution. It’s vital for heating and power generation.
27. State the uses of coke.
Answer: Reducing agent in metal extraction, fuel in industries.
Explanation: Coke’s high carbon content makes it ideal for reducing metal oxides and as an industrial fuel.
28. What are the constituents of coal gas? State one use of coal gas.
Answer: Coal gas contains methane and hydrogen.
Use: Fuel in industries.
Explanation: Its combustible nature makes it suitable for industrial heating.
29. What are the major products of petroleum refining? Give one use of each.
- Petroleum gas: Fuel in homes/industries.
- Petrol: Fuel for light motor vehicles.
- Kerosene: Fuel for wick stoves/lanterns.
- Diesel: Fuel for heavy motor vehicles.
- Lubricating oil: Lubrication in machines.
- Paraffin wax: Making candles.
- Bitumen: Road surfacing.
Explanation: Refining separates crude oil into these fractions via fractional distillation, each with specific uses.
30. What are the advantages of using natural gas (or CNG) as a fuel?
Answer: Burns easily, produces high heat, smokeless, minimal pollution, environmentally friendly.
Explanation: CNG’s clean combustion makes it a preferred fuel for vehicles and industries.
31. State the various uses of natural gas.
Answer: Domestic/industrial fuel, thermal power station fuel, hydrogen source for fertilizers.
Explanation: Its versatility supports cooking, electricity, and chemical production.
32. What is CNG? State its one use.
Answer: CNG is compressed natural gas.
Use: Fuel in transport vehicles.
Explanation: CNG is a cleaner alternative for buses and cars, stored in cylinders.
33. Where is natural gas found? Why is it called a clean fuel?
Answer: Found under the earth’s crust, often above petroleum. It’s clean because it burns smokelessly, causing minimal pollution.
Explanation: Methane’s clean combustion reduces environmental impact.
34. What are the advantages of using LPG as a fuel?
Answer: Burns easily, high calorific value, smokeless, easy to store/transport.
Explanation: LPG’s efficiency and cleanliness make it ideal for cooking and heating.
35. Name any five useful substances manufactured from petrochemicals.
Answer: Synthetic fibres, plastics, synthetic rubber, perfumes, detergents.
Explanation: Petrochemicals are used to produce essential modern materials.
36. Which material is called 'black gold'? Why?
Answer: Petroleum, due to its high commercial value.
Explanation: Its importance in energy and industry earns it the nickname 'black gold.'
37. (a) Where and when was the world’s first oil well drilled? (b) Where and when was oil first struck in India?
Answer:
a. Pennsylvania, USA, 1859.
b. Makum, Assam, 1867.
Explanation: These events marked the start of the modern oil industry in the USA and India.
38. State one use each of the following products of petroleum:
- a. Petroleum gas: Fuel in homes/industries.
- b. Petrol: Fuel for light motor vehicles.
- c. Diesel: Fuel for heavy motor vehicles.
- d. Lubricating oil: Lubrication in machines.
- e. Bitumen: Road surfacing.
Explanation: Each product is tailored to specific applications based on its properties.
39. What is the major cause of air pollution? Write various tips for minimizing the wastage of petrol/diesel while driving vehicles.
Answer:
Cause: Burning fossil fuels.
Tips: Drive at moderate speed, switch off engine when waiting, maintain tyre pressure, regular vehicle maintenance.
Explanation: These practices reduce fuel consumption and emissions, helping the environment.
40. Why should we use fossil fuels only when absolutely necessary?
Answer: They are exhaustible, cause pollution, and contribute to global warming. Conservation ensures future availability.
Explanation: Limited reserves and environmental impacts necessitate careful use.
41. State (a) two uses of kerosene, and (b) two uses of paraffin wax.
Answer:
a. Kerosene: Fuel for stoves, aviation fuel.
b. Paraffin wax: Making candles, Vaseline.
Explanation: Kerosene is a versatile fuel, while paraffin wax is used in waxy products.
Long Answer Type Questions
42. (a) What is meant by inexhaustible natural resources? Name two. (b) What is meant by exhaustible natural resources? Name any two.
Answer:
a. Inexhaustible: Unlimited resources not depleted by human use. Examples: Sunlight, Air.
b. Exhaustible: Limited resources that can be depleted. Examples: Coal, Natural gas.
Explanation: Inexhaustible resources are renewable, while exhaustible ones are finite and non-renewable.
43. (a) What are fossil fuels? Name three fossil fuels. (b) Describe how fossil fuels were formed.
Answer:
a. Fossil fuels: Fuels from ancient organic remains. Examples: Coal, Petroleum, Natural gas.
b. Formed from buried plants/animals under heat, pressure, and bacterial action over millions of years.
Explanation: Geological processes transformed organic matter into energy-rich fuels over long periods.
44. (a) What is petroleum? Where does petroleum occur? (b) Describe the process of formation of petroleum.
Answer:
a. Petroleum: Dark, viscous liquid found between rock layers.
b. Formed from marine organisms buried under the sea, transformed by heat, pressure, and bacteria.
Explanation: Petroleum forms in marine environments, trapped in geological formations.
45. (a) What are petrochemicals? Name any two petrochemicals. (b) Why are petrochemicals so important?
Answer:
a. Petrochemicals: Chemicals from petroleum/natural gas. Examples: Methyl alcohol, Ethyl alcohol.
b. Used to make detergents, plastics, fibres, perfumes, fertilizers.
Explanation: Petrochemicals are vital for producing modern materials and industrial products.
Multiple Choice Questions
46. Which one of the following is not a fossil fuel?
a. petrol
b. coke
c. charcoal
d. coal
Answer: (c) Charcoal.
Explanation: Charcoal is made from wood, not ancient organic remains like fossil fuels.
47. The major component of LPG is:
a. hydrogen
b. carbon monoxide
c. methane
d. butane
Answer: (d) Butane.
Explanation: LPG is primarily butane and propane, used as a fuel.
48. Which is the major component of CNG?
a. ethane
b. propane
c. methane
d. butane
Answer: (c) Methane.
Explanation: Methane makes CNG a clean-burning fuel.
49. The gas which occurs above the petroleum oil trapped under the rocks is called:
a. biogas
b. petroleum gas
c. natural gas
d. coal gas
Answer: (c) Natural gas.
Explanation: Natural gas is often found above petroleum deposits in reservoirs.
50. Which of the following is being used as a source of hydrogen gas needed to manufacture fertilizers?
a. biogas
b. natural gas
c. coal gas
d. petroleum gas
Answer: (b) Natural gas.
Explanation: Methane from natural gas is processed to produce hydrogen for fertilizers.
51. One of the following is not an exhaustible source of energy. This one is:
a. natural gas
b. petroleum gas
c. coal gas
d. biogas
Answer: (d) Biogas.
Explanation: Biogas is renewable, produced from organic waste, unlike fossil fuels.
52. The slow process by which large land plants and trees buried deep under the earth have become coal is called:
a. carbonation
b. carburetion
c. carbonization
d. carbocation
Answer: (c) Carbonization.
Explanation: Carbonization is the geological process forming coal from plant matter.
53. Which of the following is used as a reducing agent in the extraction of iron metal?
a. coal
b. bitumen
c. charcoal
d. coke
Answer: (d) Coke.
Explanation: Coke reduces iron oxide to iron in a blast furnace.
54. Which of the following is usually referred to as 'black gold'?
a. coke
b. coal tar
c. petroleum
d. coal
Answer: (c) Petroleum.
Explanation: Petroleum’s economic value and dark color earn it the nickname 'black gold.'
55. The various compounds present in coal tar are separated by the process of:
a. simple distillation
b. destructive distillation
c. fractional distillation
d. fractional crystallization
Answer: (c) Fractional distillation.
Explanation: Fractional distillation separates coal tar components by their boiling points.
56. Which of the following is not obtained as a fraction during the refining of petroleum?
a. kerosene
b. natural gas
c. lubricating oil
d. bitumen
Answer: (b) Natural gas.
Explanation: Natural gas is extracted separately, not produced during petroleum refining.
57. Which one of the following is an inexhaustible natural resource?
a. coal
b. petroleum
c. water
d. forests
Answer: (c) Water.
Explanation: Water is renewable through the water cycle, unlike finite fossil fuels.
High Order Thinking Skills (HOTS) Questions
58. The substance W is a fossil fuel. It occurs deep below the ground in certain areas of the earth. Another fossil fuel X is found trapped above the deposits of W. When W is subjected to a process called Y, then a number of different products are collected at different temperature ranges which are put to different uses. A special grade of product Z obtained in this way is used as aviation fuel in jet aeroplanes.
a. What are (i) W, and (ii) X?
b. What is the physical state of (i) W, and (ii) X?
c. Name the process Y?
d. Name the product Z?
Answer:
a. (i) W: Petroleum, (ii) X: Natural gas.
b. (i) W: Thick liquid, (ii) X: Gas.
c. Process Y: Fractional distillation.
d. Product Z: Kerosene.
Explanation: Petroleum (W) is a dark, oily liquid found underground, refined through fractional distillation (Y) to produce kerosene (Z), used as aviation fuel. Natural gas (X), a gas, is often found above petroleum due to its lighter nature.
59. The material A is a fossil fuel which is extracted from the earth. It is said to be formed from the buried, large land plants by a very slow process B. When A is heated in the absence of air in a process called C, then it gives three products D, E, and F. The product D is used as a reducing agent in the extraction of metals, the product E is used as an industrial fuel whereas the product F has been traditionally used for metalling the roads.
a. What could material A be?
b. What is (i) physical state, and (ii) colour, of A?
c. Name the processes (i) B, and (ii) C.
d. What are (i) D, (ii) E, and (iii) F?
Answer:
a. A: Coal.
b. (i) Physical state: Solid, (ii) Colour: Black.
c. (i) Process B: Carbonization, (ii) Process C: Destructive distillation.
d. (i) D: Coke, (ii) E: Coal gas, (iii) F: Coal tar.
Explanation: Coal (A), a solid black fossil fuel, forms by carbonization (B) of buried plants. Destructive distillation (C) of coal produces coke (D) for metal extraction, coal gas (E) as industrial fuel, and coal tar (F) for chemicals and past road surfacing.
60. The fossil fuel P is formed under the earth by the decomposition of vegetable matter lying under water by the action of anaerobic bacteria. The major component of fuel P is Q. The fossil fuel P is used as a source of gas R needed to manufacture nitrogenous fertilizers. When P is filled in metal cylinders and used as a fuel in motor vehicles, it is called S. What are P, Q, R, and S?
Answer:
P: Natural gas, Q: Methane, R: Hydrogen, S: Compressed Natural Gas (CNG).
Explanation: Natural gas (P), mainly methane (Q), forms from underwater plant matter decomposed by anaerobic bacteria. It’s processed to produce hydrogen (R) for fertilizers and compressed into CNG (S) for vehicle fuel, known for its clean combustion.
No comments:
Post a Comment