Extra 30 short questions and answers from the chapter:3 "Coal and Petroleum" for Class 8 Science (CBSE):-
1. What are natural resources?
Ans: Natural resources are materials provided by nature that are useful to humans, such as air, water, sunlight, minerals, forests, and fossil fuels.
2. What are fossil fuels? Name three fossil fuels.
Ans: Fossil fuels are energy-rich substances formed from the remains of dead plants and animals over millions of years. Examples:
Coal
Petroleum
Natural Gas
3. What is coal? How is it formed?
Ans: Coal is a black, hard, and combustible substance formed from dead plant remains buried under the earth's surface for millions of years. The process of coal formation is called carbonization.
4. Name the different products obtained from coal.
Ans: The main products obtained from coal are:
Coke
– Used as a fuel and in steel manufacturing.
Coal Tar
– Used in making roads and chemicals.
Coal Gas
– Used as a fuel in industries.
5. What is petroleum? How is it formed?
Ans: Petroleum is a liquid fossil fuel formed from the remains of tiny marine organisms buried under the sea millions of years ago. Due to high pressure and temperature, these remains converted into petroleum and natural gas.
6. What is coke? Mention its uses.
Ans: Coke is a tough, porous, and black substance obtained from coal.
Uses:
Used in the manufacture of steel.
Used in the extraction of metals.
7. What is coal gas? How is it obtained?
Ans: Coal gas is a mixture of hydrogen, methane, and carbon monoxide. It is obtained as a by-product when coal is processed to make coke.
8. What is coal tar? Mention its uses.
Ans: Coal tar is a thick, black liquid with an unpleasant smell.
Uses:
Used in making synthetic dyes, paints, and explosives.
Used in making waterproof materials.
9. What is meant by refining of petroleum?
Ans: Refining of petroleum is the process of separating crude oil into different useful components such as petrol, diesel, kerosene, and lubricating oil. It is done in an oil refinery by fractional distillation.
10. Name the main components of petroleum and their uses.
Ans: The main components of petroleum are:
Petrol
– Used in vehicles and as a solvent.
Diesel
– Used in trucks, buses, and generators.
Kerosene
– Used in jet engines and cooking fuel.
11. Why is petroleum called "black gold"?
Ans: Petroleum is called "black gold" because it is black in colour when extracted and is very valuable due to its multiple uses in fuels and industries.
12. What is CNG? Mention its advantages.
Ans: CNG (Compressed Natural Gas) is a clean fuel used in vehicles.
Advantages:
Produces less pollution.
Cheaper than petrol and diesel.
Burns efficiently and leaves no residue.
13. How is natural gas stored and transported?
Ans: Natural gas is stored under high pressure in cylinders or transported through pipelines over long distances.
14. What are the disadvantages of using fossil fuels?
Ans:
Non-renewable
– Limited supply, takes millions of years to form.
Causes pollution
– Releases harmful gases, leading to air pollution.
Contributes to global warming
– Increases carbon dioxide levels.
15. How can we conserve fossil fuels?
Ans:
Use
public transport
instead of private vehicles.
Use
renewable energy
like solar and wind power.
Turn off
unnecessary electrical appliances
.
16. What is the difference between renewable and non-renewable resources?
Ans:
Renewable resources
: Can be replenished (e.g., sunlight, wind).
Non-renewable resources
: Limited and take millions of years to form (e.g., coal, petroleum).
17. What are the uses of diesel?
Ans: Diesel is used in:
Heavy vehicles
like buses and trucks.
Generators
for electricity production.
18. What are the harmful effects of burning coal?
Ans:
Releases
carbon dioxide
, causing global warming.
Produces
smoke
and
ash
, leading to air pollution.
Causes
acid rain
, which damages crops and buildings.
19. What is fractional distillation?
Ans: Fractional distillation is the process of separating petroleum into different useful components based on their boiling points.
20. What is LPG? What are its advantages?
Ans: LPG (Liquefied Petroleum Gas) is a clean cooking fuel.
Advantages:
Produces no smoke.
Easy to store and transport.
Highly efficient and clean.
21. Why is natural gas considered an ideal fuel?
Ans:
Produces
less pollution
than coal and petrol.
Easily available
and can be transported through pipelines.
High calorific value
, meaning more energy per unit.
22. What are petrochemicals? Give two examples.
Ans: Petrochemicals are chemicals derived from petroleum and natural gas.
Examples:
Plastic
– Used in packaging and containers.
Synthetic
fibres
– Used in clothes and ropes.
23. How does burning fossil fuels contribute to acid rain?
Ans:
Burning coal and petroleum releases
sulphur
dioxide (SO₂) and nitrogen oxides (NOx)
.
These gases combine with water vapor to form
acid rain
, which harms crops, buildings, and water bodies.
24. What are hydrocarbons?
Ans: Hydrocarbons are organic compounds of carbon and hydrogen found in fossil fuels like petrol and natural gas.
25. What is the composition of natural gas?
Ans: Natural gas mainly contains methane (CH₄), along with small amounts of ethane and propane.
26. What is the role of coal in electricity generation?
Ans: Coal is burned in thermal power plants to produce heat, which converts water into steam. This steam runs turbines to generate electricity.
27. Why should fossil fuels be used wisely?
Ans:
They are
limited
and take millions of years to form.
Burning them causes
pollution
and
global warming
.
Conservation ensures their
availability for future generations
.
28. How does petroleum drilling affect the environment?
Ans:
Oil spills
harm marine life.
Deforestation
occurs for drilling sites.
Air pollution
due to extraction and burning.
29. How does burning of coal affect human health?
Ans:
Causes
respiratory diseases
like asthma.
Produces
toxic gases
like carbon monoxide.
Leads to
lung infections
and allergies.
30. What can be used as an alternative to fossil fuels?
Ans: Renewable energy sources like solar power, wind energy, hydroelectricity, and biofuels can replace fossil fuels.
