Coal and Petroleum – Very Short Answer Type Questions
Class 8 • Science
Chapter 5 — Coal and Petroleum
CBSE Board Examinations — Quick overview
Topic A — Introduction & Definitions (1–6)
1. What are fossil fuels?
Fossil fuels are energy-rich substances formed from remains of dead plants and animals over millions of years.
2. Name two major fossil fuels discussed in this chapter.
Coal and petroleum (crude oil).
3. What is crude oil?
Crude oil (petroleum) is a mixture of many hydrocarbons formed from marine organisms.
4. Define coal in one sentence.
Coal is a solid fossil fuel formed from plant remains buried under sediments and transformed by heat and pressure.
5. What is natural gas mainly composed of?
Natural gas is mainly composed of methane (CH₄).
6. What is LPG?
LPG (liquefied petroleum gas) is a mixture of propane and butane used as domestic fuel.
Topic B — Formation & Types of Coal (7–14)
7. What is carbonisation?
Carbonisation is the process where plant remains are transformed into coal under heat and pressure over time.
8. Name the stages in coal formation from lowest to highest rank.
Peat → Lignite → Bituminous coal → Anthracite.
9. Which type of coal has the highest carbon content?
Anthracite has the highest carbon content.
10. Which coal is called brown coal?
Lignite is often called brown coal.
11. Give one use of bituminous coal.
Used in thermal power plants to generate electricity.
12. What impurities are commonly found in coal?
Coal commonly contains sulfur, ash-forming minerals, and moisture.
Topic C — Uses & Disadvantages of Coal (15–20)
13. Name two uses of coal.
Electricity generation and manufacture of coke for iron and steel industry.
14. What is coke?
Coke is a high-carbon fuel obtained by heating coal in absence of air; used in metallurgy.
15. What harmful gases are released by burning coal?
Carbon dioxide (CO₂), carbon monoxide (CO), and sulfur dioxide (SO₂).
16. How does coal mining affect land?
Mining can cause land degradation, deforestation and soil erosion.
17. Give one health effect of air pollution from coal burning.
Respiratory problems like asthma and bronchitis.
18. Why is coal considered non-renewable?
Because it takes millions of years to form and cannot be replenished quickly.
Topic D — Petroleum Formation & Crude Oil (21–26)
19. From what organisms is petroleum formed?
From remains of tiny marine organisms (plankton) and plants deposited on sea beds.
20. What conditions are necessary for formation of petroleum?
Burial under sediments, heat, pressure, and time.
21. What is a hydrocarbon?
A compound made of hydrogen and carbon atoms (e.g., methane, octane).
22. Is crude oil a pure substance?
No, crude oil is a complex mixture of many hydrocarbons and impurities.
23. Where is petroleum commonly found?
In underground reservoirs, often with natural gas, beneath sedimentary rock layers.
24. Name one impurity present in crude oil.
Sulfur compounds are common impurities in crude oil.
Topic E — Fractional Distillation of Petroleum (27–34)
25. What is fractional distillation?
A process that separates components of a mixture based on different boiling points.
26. What is the main purpose of fractional distillation of crude oil?
To separate crude oil into useful fractions like petrol, diesel, kerosene, etc.
27. In a fractionating column, where do lighter fractions condense?
Lighter fractions condense at the top of the column where the temperature is lower.
28. Which fraction is collected near the top and used as petrol?
Petrol (gasoline) is collected near the top as a light fraction.
29. Which heavy fraction is used for road surfacing?
Bitumen is the heavy fraction used for road surfacing and roofing.
30. Which fraction is commonly used as aviation fuel?
Kerosene is commonly used as aviation fuel (jet fuel) and for heating.
31. What happens to very heavy residues at the bottom?
They form bitumen or are further processed for lubricants and heavy oils.
Topic F — Uses of Petroleum Products (35–40)
32. Name two transport fuels obtained from petroleum.
Petrol (gasoline) and diesel.
33. Name a petroleum product used as a lubricant.
Lubricating oil.
34. Which petroleum fraction is a raw material for plastics?
Naphtha is used as a feedstock for petrochemical industries to make plastics.
35. What is bitumen mainly used for?
Bitumen is used for road construction and roofing.
36. Give one domestic use of LPG.
Cooking (in gas stoves) is a common domestic use of LPG.
Topic G — Natural Gas & LPG (41–44)
37. How is natural gas transported over long distances?
Natural gas is transported through pipelines; liquefied form (LNG) is transported by ships.
38. What is the advantage of natural gas over coal?
Natural gas burns cleaner, producing less smoke and fewer pollutants than coal.
39. Why is LPG stored under pressure?
Under pressure LPG becomes liquid, making it easier and safer to store and transport.
40. Give one safety precaution while using LPG cylinders.
Check for leaks using soapy water; keep cylinders upright and away from heat sources.
Topic H — Environmental Impact & Conservation (45–50)
41. Name a greenhouse gas released from burning fossil fuels.
Carbon dioxide (CO₂) is a major greenhouse gas released.
42. What is acid rain and which fossil fuel pollutant causes it?
Acid rain is precipitation made acidic by sulfur dioxide (SO₂) and nitrogen oxides; SO₂ from coal burning contributes to it.
43. Mention one impact of oil spills.
Oil spills harm marine life, birds, and coastal ecosystems by coating and poisoning organisms.
44. State one way to conserve fossil fuels.
Use public transport, improve fuel efficiency, and switch to renewable energy sources.
45. Why should we use cleaner fuels?
Cleaner fuels reduce air pollution and health hazards and lower greenhouse gas emissions.
46. Give one method to reduce pollution from vehicles.
Promote electric vehicles and regular vehicle maintenance to reduce emissions.
47. What is biogas and how is it related to fossil fuels?
Biogas is produced from organic waste and is a renewable alternative to fossil fuels.
48. Which energy source is non-polluting and can replace fossil fuels?
Renewable sources like solar and wind energy are non-polluting alternatives.
49. What does the term 'reserve' mean in context of fossil fuels?
Reserve refers to the quantity of fossil fuel that can be extracted economically using current technology.
50. Why is it important to study coal and petroleum in Class 8 science?
To understand sources of energy, their uses, environmental impacts and the need for conservation and alternatives.