Coal and Petroleum – MCQs with Answers and Explanations
Class 8 • Science
Chapter 5 — Coal and Petroleum
CBSE Board Examinations — Systematic overview
Topic 1 — Basics & Definitions (10 MCQs)
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1. Fossil fuels are mainly formed from:Answer: BFossil fuels like coal and petroleum are formed from the remains of plants and animals buried under sediments and transformed by heat and pressure over millions of years.
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2. The major component of natural gas is:Answer: BNatural gas is primarily composed of methane (CH₄), which is a clean-burning fuel used for cooking and electricity generation.
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3. LPG stands for:Answer: CLPG means Liquefied Petroleum Gas, primarily a mixture of propane and butane stored as a liquid under pressure for domestic and industrial use.
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4. Which of the following is a solid fossil fuel?Answer: CCoal is a solid fossil fuel formed from plant remains; petroleum and natural gas are liquid and gaseous fuels respectively.
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5. Crude oil is primarily a mixture of:Answer: CCrude oil is a complex mixture of hydrocarbons — compounds made of hydrogen and carbon atoms.
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6. Which of the following is NOT a fossil fuel?Answer: CSolar energy is a renewable energy source, not a fossil fuel which is formed from ancient biological matter.
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7. Which is the earliest stage in coal formation?Answer: CPeat is the earliest stage of coal formation — partially decayed plant matter that can later transform into lignite and higher ranks of coal.
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8. Which fraction of crude oil is used as a fuel in aircraft?Answer: CKerosene is used as aviation fuel (jet fuel) and also for heating and lighting in some regions.
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9. Which of these is a heavy fraction from crude oil used in road construction?Answer: CBitumen is the heavy residue used for road surfacing and roofing due to its sticky, waterproof properties.
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10. The term 'reserve' in context of fossil fuels means:Answer: BReserves are the portion of resources that can be extracted economically with current technology and under present market conditions.
Topic 2 — Formation & Types of Coal (8 MCQs)
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11. Which process transforms plant remains into coal?Answer: BCarbonisation under heat and pressure converts plant remains into coal through stages like peat, lignite, bituminous and anthracite.
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12. Which coal type has the highest carbon content?Answer: DAnthracite is the highest rank of coal with the highest carbon content and calorific value.
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13. Lignite is mainly used in:Answer: BLignite (brown coal) is a low-grade coal commonly used in some thermal power plants for electricity generation.
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14. Which of the following decreases as coal rank increases?Answer: BAs coal rank increases (towards anthracite), moisture and volatile matter decrease while carbon content and calorific value increase.
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15. Peat is used as:Answer: BPeat is partially decayed plant matter sometimes used locally as a fuel source, though it has low calorific value compared to higher rank coals.
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16. Which impurity in coal contributes to acid rain when burned?Answer: BSulfur in coal forms sulfur dioxide on combustion, which can lead to acid rain after atmospheric reactions.
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17. Which process is used to obtain coke from coal?Answer: BDestructive distillation of coal in absence of air yields coke, coal gas and coal tar.
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18. Which coal type produces the least smoke when burnt?Answer: CAnthracite burns cleaner with less smoke due to high carbon and low volatile matter.
Topic 3 — Fractional Distillation & Refining (10 MCQs)
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19. Fractional distillation separates crude oil components based on:Answer: BDifferent hydrocarbons have different boiling points, so they condense at different heights in the fractionating column.
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20. Which fraction is collected at the top of a fractionating column?Answer: CLighter fractions like petrol (gasoline) with low boiling points condense near the top of the column.
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21. Cracking in petroleum refining is used to:Answer: BCracking breaks large hydrocarbon molecules into smaller, more useful molecules like petrol to increase yield of lighter fuels.
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22. Which process removes sulfur compounds from petroleum fractions?Answer: AHydrotreating (catalytic desulfurisation) uses hydrogen to convert sulfur compounds into hydrogen sulfide which is removed, reducing SO₂ emissions on burning.
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23. Naphtha obtained from crude oil is mainly used in:Answer: BNaphtha is used as a feedstock in petrochemical industries for producing plastics and other chemicals.
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24. Which fraction has the highest boiling point?Answer: DBitumen is the heaviest residue with the highest boiling point, collected at the bottom of the fractionating column.
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25. Which of the following is a lubricant fraction?Answer: BLubricating oil is a middle-to-heavy fraction used to reduce friction in machines.
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26. Why is fractional distillation performed at different levels in the column?Answer: BThe column has a temperature gradient; fractions condense where the temperature matches their boiling points, allowing collection at different levels.
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27. Which refinery process improves octane number of petrol?Answer: BReforming rearranges hydrocarbon molecules to increase octane number and improve petrol quality for engines.
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28. The fraction used for making detergents and plastics is:Answer: ANaphtha serves as feedstock for petrochemical industries to make plastics, detergents and other chemicals.
Topic 4 — Uses & Products of Coal and Petroleum (10 MCQs)
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29. Which fuel is commonly used in domestic cooking in cylinder form?Answer: CLPG is used widely for domestic cooking due to its clean flame and convenient storage in cylinders.
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30. Which petroleum product is used as a raw material for plastics?Answer: BNaphtha is an important feedstock for the petrochemical industry to manufacture plastics and synthetic fibres.
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31. Which fuel is preferred for running diesel engines?Answer: BDiesel is used in compression-ignition engines commonly found in heavy vehicles and some generators.
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32. Which product from coal is used in metallurgy as a reducing agent?Answer: CCoke, produced by destructive distillation of coal, is used in blast furnaces as a fuel and reducing agent in iron and steel production.
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33. Bitumen is mainly used for:Answer: BBitumen's adhesive and waterproof properties make it ideal for road surfacing and roofing.
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34. Which petroleum fraction is used as a solvent and in chemical industries?Answer: BNaphtha and similar light fractions are used as solvents and feedstock in chemical and petrochemical industries.
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35. Which fuel has the highest energy per unit mass among common fossil fuels?Answer: CLiquid petroleum fuels (like diesel) generally have higher energy density per unit mass compared to coal and wood.
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36. Which petroleum product is commonly used for lighting in some regions?Answer: BKerosene is used in lamps for lighting and as an aviation fuel; historically common for household lighting in areas without electricity.
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37. Which of these is NOT a use of petroleum products?Answer: CWhile petrochemicals are feedstocks for many chemicals, fertilisers are typically produced from natural gas (for ammonia) and other sources; petroleum is not directly used to make fertilisers in most processes.
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38. Which product from petroleum refining is commonly used to make synthetic fibres?Answer: BNaphtha is a feedstock for the petrochemical industry, which produces monomers used to make synthetic fibres such as polyester and nylon.
Topic 5 — Environmental Impact & Conservation (6 MCQs)
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39. Burning fossil fuels increases which greenhouse gas in the atmosphere?Answer: CCombustion of fossil fuels releases carbon dioxide (CO₂), a major greenhouse gas contributing to global warming.
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40. Acid rain is mainly caused by emissions of:Answer: BSulfur dioxide (SO₂) and nitrogen oxides (NOₓ) from burning fossil fuels form acids in the atmosphere that lead to acid rain.
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41. Which method can reduce air pollution from coal power plants?Answer: AElectrostatic precipitators remove particulates and scrubbers reduce sulfur emissions, helping control pollution from coal plants.
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42. One effective way to conserve fossil fuels is to:Answer: BPromoting public transport and fuel-efficient vehicles lowers per-capita fuel consumption and reduces overall fossil fuel demand.
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43. Which renewable energy source can replace fossil fuels for electricity generation without direct emissions?Answer: BSolar energy generates electricity without direct emissions of greenhouse gases and can help replace fossil fuel-based power.
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44. Oil spills mainly affect:Answer: BOil spills coat marine organisms, damage food chains and pollute coastlines, severely impacting marine life and livelihoods.
Topic 6 — Natural Gas, LPG & Safety (6 MCQs)
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45. How is LPG stored for domestic use?Answer: BLPG is liquefied under pressure and stored in cylinders, making it convenient and safe for transport and domestic use.
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46. Which gas is mainly present in biogas?Answer: BBiogas primarily contains methane produced by anaerobic decomposition of organic waste; it is a renewable alternative to fossil fuels.
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47. One safety precaution with LPG cylinders is to:Answer: BCylinders should be upright in ventilated areas and checked for leaks using soapy water; storing near heat or in closed rooms is dangerous.
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48. LNG stands for:Answer: CLNG means Liquefied Natural Gas — natural gas cooled to very low temperatures to become liquid for transport.
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49. Which is a clean-burning fuel commonly used in urban areas?Answer: CNatural gas burns cleaner with fewer particulates and sulfur compounds compared to coal, making it suitable for urban use.
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50. To detect a leak in an LPG connection, you should:Answer: CApplying soapy water around connections will show bubbles if there's a leak — a safe, recommended method. Never use a flame to check for leaks.