Chapter 3 Coal And Petroleum Question Answers

Class 8 Ncert Question and Answers, NCERT Class 8 Science Question/Answers / By

Important Terms to Learn Before Starting Making Notes 🗒

Coal (कोयला): A black or brownish-black sedimentary rock that is used as a fuel and in the production of electricity.
Coal Gas (कोयला गैस): A flammable gaseous fuel made from coal and used for heating and lighting.
Coal Tar (कोलतार): A thick, black liquid produced during the process of making coke from coal and used in road construction and medical treatments.
Coke (कोक): A porous, carbon-rich solid derived from coal, used in metallurgy and as a fuel.
Fossil Fuel (जीवाश्म ईंधन): Natural fuels formed from the remains of living organisms over millions of years, such as coal, oil, and natural gas.
Natural Gas (प्राकृतिक गैस): A gaseous fossil fuel consisting mainly of methane, used for heating, cooking, and electricity generation.
Petroleum (पेट्रोलियम): A liquid fossil fuel that is refined to produce fuels such as gasoline, diesel, and jet fuel.
Petroleum Refinery (पेट्रोलियम रिफाइनरी): An industrial process plant where crude oil is processed and refined into useful petroleum products.
Charcoal (लकड़ी का कोयला): A lightweight, black residue consisting of carbon and ash, obtained by removing water and other volatile constituents from animal and vegetation substances.

Exercise Question Starts Here: Start Working 🖊️

1. What Are the Advantages of Using CNG and LPG as Fuels?

Compressed Natural Gas (CNG):

  1. Environmentally Friendly: CNG produces fewer harmful emissions compared to petrol and diesel, reducing air pollution.
  2. Economical: CNG is generally cheaper than other fossil fuels.
  3. Safety: CNG is stored in high-pressure cylinders, which are less prone to leakage and explosion.
  4. Efficiency: Vehicles running on CNG have better fuel efficiency and longer engine life.

Liquefied Petroleum Gas (LPG):

  1. Cleaner Combustion: LPG burns more cleanly than petrol and diesel, producing fewer pollutants and greenhouse gases.
  2. Versatility: LPG can be used for cooking, heating, and powering vehicles.
  3. Cost-effective: LPG is often more economical than other fuels for domestic and industrial use.
  4. Convenience: LPG can be easily transported and stored in cylinders, making it accessible for various applications.

2. Name the Petroleum Product Used for Surfacing of Roads.

Bitumen (बिटुमेन) is the petroleum product used for surfacing roads. It is a black, sticky, and highly viscous liquid or semi-solid form of petroleum.

3. Describe How Coal is Formed from Dead Vegetation. What is This Process Called?

Coal is formed from the remains of dead vegetation over millions of years. The process involves several stages:

  1. Accumulation: Dead plants and trees accumulate in swampy areas and are buried under water and sediment.
  2. Compaction: Over time, the accumulated vegetation is buried deeper and subjected to high pressure and temperature.
  3. Carbonization: The buried vegetation undergoes chemical and physical changes, losing moisture and volatile substances, and becoming rich in carbon.

This process is called carbonization (कार्बोनाइज़ेशन).

4. Fill in the Blanks

(a) Fossil fuels are coal, petroleum, and natural gas. (b) The process of separation of different constituents from petroleum is called refining. (c) The least polluting fuel for a vehicle is CNG (Compressed Natural Gas).

5. Tick True/False Against the Following Statements

  • (a) Fossil fuels can be made in the laboratory. (False)
  • (b) CNG is more polluting fuel than petrol. (False)
  • (c) Coke is almost pure form of carbon. (True)
  • (d) Coal tar is a mixture of various substances. (True)
  • (e) Kerosene is not a fossil fuel. (False)

6. Explain Why Fossil Fuels Are Exhaustible Natural Resources.

Fossil fuels are considered exhaustible natural resources because they are formed over millions of years from the remains of dead plants and animals. The rate of consumption far exceeds the rate of their formation, leading to their depletion. Once used, they cannot be replenished on a human timescale, making them non-renewable and finite resources.

7. Describe Characteristics and Uses of Coke.

Characteristics:

  1. High Carbon Content: Coke is almost pure carbon.
  2. Hard and Porous: Coke is hard and porous, making it an excellent fuel.
  3. High Calorific Value: Coke produces a large amount of heat when burned.

Uses:

  1. Fuel: Coke is used as a fuel in industries, especially in steel manufacturing.
  2. Reducing Agent: In the extraction of metals from their ores in metallurgical processes.
  3. Industrial Applications: Used in the production of chemicals like calcium carbide.

8. Explain the Process of Formation of Petroleum.

Petroleum is formed from the remains of marine plants and animals that settled at the bottom of ancient seas. The process involves several stages:

  1. Accumulation: Dead marine organisms accumulate on the sea floor and are buried by sediment.
  2. Burial and Compaction: Over millions of years, the organic material is buried deeper and subjected to heat and pressure, transforming into a waxy substance called kerogen.
  3. Thermal Decomposition: With continued burial, heat, and pressure, kerogen undergoes thermal decomposition, breaking down into liquid and gaseous hydrocarbons, forming petroleum and natural gas.
  4. Migration: The formed hydrocarbons migrate through porous rock layers until trapped by non-porous rocks, creating petroleum reservoirs.

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.

Data for the Graph:

S. No.YearShortage (%)
119917.9
219927.8
319938.3
419947.4
519957.1
619969.2
7199711.5

Creating the Graph:

Here is a simple way to visualize the data:

  1. X-axis: Years (1991 to 1997)
  2. Y-axis: Shortage Percentage (0% to 12%)

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