1. Which of the following is the primary source of energy on Earth?
a) Coal
b) Sun
c) Petroleum
d) Natural Gas
Answer: b) Sun
Explanation: All fossil fuels and biomass originate from solar energy stored through photosynthesis.
2. Fuel is defined as:
a) A substance that produces heat on dissolution in water
b) A substance that produces energy when oxidized
c) A substance that increases temperature when cooled
d) A substance that absorbs oxygen
Answer: b) A substance that produces energy when oxidized
Explanation: Fuels release heat/energy by combustion (oxidation).
3. The unit of calorific value of fuel is:
a) J/kg
b) J/mol
c) J/m³
d) All of the above
Answer: a) J/kg
Explanation: Calorific value is usually expressed in Joules per kilogram for solids/liquids.
4. Which fuel has the highest calorific value?
a) Hydrogen
b) Coal
c) LPG
d) Methane
Answer: a) Hydrogen
Explanation: Hydrogen has ~150 kJ/g, highest among common fuels.
5. Which fuel is called the “fuel of the future”?
a) LPG
b) Hydrogen
c) Biogas
d) Kerosene
Answer: b) Hydrogen
Explanation: Hydrogen is clean, produces only water on combustion.
6. The calorific value of LPG is about:
a) 20–25 kJ/g
b) 35–40 kJ/g
c) 45–50 kJ/g
d) 55–60 kJ/g
Answer: c) 45–50 kJ/g
Explanation: LPG has high calorific value compared to coal and wood.
7. Which of the following is not a fossil fuel?
a) Coal
b) Petroleum
c) LPG
d) Hydrogen
Answer: d) Hydrogen
Explanation: Hydrogen is not derived from fossils.
8. Which fuel is used in nuclear power plants?
a) Uranium-235
b) Methane
c) Coal
d) LPG
Answer: a) Uranium-235
Explanation: Uranium-235 undergoes nuclear fission to release energy.
9. Which fuel is used in rockets?
a) Petrol
b) Diesel
c) Hydrogen + Oxygen
d) Coal gas
Answer: c) Hydrogen + Oxygen
Explanation: Liquid hydrogen and liquid oxygen are used as propellants.
10. Which is a renewable source of fuel?
a) Coal
b) Petroleum
c) Biogas
d) Diesel
Answer: c) Biogas
Explanation: Biogas is produced from biomass, renewable and sustainable.
11. Wood is considered a:
a) Primary fuel
b) Secondary fuel
c) Artificial fuel
d) Synthetic fuel
Answer: a) Primary fuel
Explanation: Wood is a natural, primary source of energy.
12. Petrol is obtained from:
a) Coal distillation
b) Fractional distillation of petroleum
c) Natural gas
d) Biogas
Answer: b) Fractional distillation of petroleum
Explanation: Petroleum products are separated by fractional distillation.
13. Which of the following is not a petroleum product?
a) Diesel
b) Kerosene
c) Coke
d) Petrol
Answer: c) Coke
Explanation: Coke is obtained from coal, not petroleum.
14. Octane number is related to:
a) Quality of diesel
b) Quality of petrol
c) Quality of coal
d) Quality of LPG
Answer: b) Quality of petrol
Explanation: Octane number measures anti-knocking quality of petrol.
15. The main constituent of CNG is:
a) Butane
b) Propane
c) Methane
d) Ethane
Answer: c) Methane
Explanation: CNG mainly contains methane (~90%).
16. Which gas is used as a domestic fuel in rural areas?
a) Coal gas
b) Biogas
c) Natural gas
d) LPG
Answer: b) Biogas
Explanation: Biogas plants in villages produce methane-rich gas.
17. Which fuel produces least pollution?
a) Petrol
b) Coal
c) LPG
d) Hydrogen
Answer: d) Hydrogen
Explanation: Hydrogen produces only water vapor after combustion.
18. Calorific value of coal is about:
a) 15–20 kJ/g
b) 20–25 kJ/g
c) 30–35 kJ/g
d) 40–45 kJ/g
Answer: b) 20–25 kJ/g
Explanation: Average calorific value of coal lies around 20–25 kJ/g.
19. Which of the following fuels is solid?
a) Petrol
b) LPG
c) Wood
d) Natural gas
Answer: c) Wood
Explanation: Solid fuels include coal, wood, coke.
20. Which gas is a major component of water gas?
a) CO and H₂
b) CO and CH₄
c) CO₂ and H₂
d) CH₄ and H₂
Answer: a) CO and H₂
Explanation: Water gas is CO + H₂, used as industrial fuel.
21. Producer gas is:
a) CO + H₂
b) CO + N₂
c) CO₂ + O₂
d) CH₄ + CO₂
Answer: b) CO + N₂
Explanation: Producer gas is made from coke + air.
22. Which of the following has maximum energy per gram?
a) Petrol
b) Diesel
c) Coal
d) Hydrogen
Answer: d) Hydrogen
Explanation: Hydrogen has highest calorific value.
23. Which of the following is a non-renewable fuel?
a) Biogas
b) Coal
c) Firewood
d) Charcoal
Answer: b) Coal
Explanation: Coal takes millions of years to form.
24. LPG mainly consists of:
a) Butane + Propane
b) Ethane + Methane
c) Butane + Methane
d) Methane + CO₂
Answer: a) Butane + Propane
Explanation: LPG is a mixture of butane and propane.
25. Which gas is commonly known as “marsh gas”?
a) CO₂
b) CH₄
c) H₂
d) CO
Answer: b) CH₄
Explanation: Methane is called marsh gas, produced in swamps.
26. The primary constituent of coal is:
a) Carbon
b) Hydrogen
c) Nitrogen
d) Oxygen
Answer: a) Carbon
Explanation: Coal is mainly carbon with small amounts of hydrogen, nitrogen, sulfur, and oxygen.
27. The purest form of coal is:
a) Lignite
b) Bituminous
c) Anthracite
d) Peat
Answer: c) Anthracite
Explanation: Anthracite has the highest carbon content (~90%) and highest calorific value.
28. Which variety of coal has the least carbon content?
a) Lignite
b) Peat
c) Bituminous
d) Anthracite
Answer: b) Peat
Explanation: Peat is the lowest grade, with least carbon (~50–60%).
29. Which gas is formed when coal burns with insufficient oxygen?
a) CO₂
b) CH₄
c) CO
d) SO₂
Answer: c) CO
Explanation: Incomplete combustion of carbon forms poisonous carbon monoxide.
30. Destructive distillation of coal gives:
a) Coke, coal tar, coal gas
b) Petrol, kerosene, diesel
c) Coke, methane, hydrogen
d) Graphite, diamond, soot
Answer: a) Coke, coal tar, coal gas
Explanation: Heating coal in absence of air produces coke, coal tar, and coal gas.
31. Which petroleum fraction has the lowest boiling point?
a) Diesel
b) Petrol
c) Kerosene
d) Lubricating oil
Answer: b) Petrol
Explanation: Petrol boils at ~40–200°C, lower than kerosene and diesel.
32. Diesel is obtained from petroleum by:
a) Filtration
b) Distillation
c) Fractional distillation
d) Condensation
Answer: c) Fractional distillation
Explanation: Petroleum is separated into fractions based on boiling points.
33. The main constituent of natural gas is:
a) Methane
b) Ethane
c) Propane
d) Butane
Answer: a) Methane
Explanation: Natural gas contains ~85–95% methane.
34. Which fuel is called “blue fuel”?
a) Coal gas
b) Biogas
c) Natural gas
d) LPG
Answer: c) Natural gas
Explanation: Natural gas burns with a blue flame, hence “blue fuel”.
35. CNG stands for:
a) Compressed Natural Gas
b) Combined Natural Gas
c) Common Natural Gas
d) Concentrated Natural Gas
Answer: a) Compressed Natural Gas
Explanation: CNG is methane compressed at high pressure.
36. Biogas is mainly composed of:
a) CO₂ + H₂
b) CH₄ + CO₂
c) CO + N₂
d) C₂H₆ + CH₄
Answer: b) CH₄ + CO₂
Explanation: Biogas contains ~55–70% methane and ~30–40% CO₂.
37. Biogas is produced by:
a) Fermentation
b) Aerobic decomposition
c) Anaerobic decomposition
d) Oxidation
Answer: c) Anaerobic decomposition
Explanation: Methanogens break down biomass in absence of oxygen to produce methane.
38. Which of the following is a cleaner fuel?
a) Coal
b) Wood
c) LPG
d) Diesel
Answer: c) LPG
Explanation: LPG burns completely and produces less smoke.
39. Which of the following gases causes “coal mine explosions”?
a) CO₂
b) CH₄
c) H₂
d) SO₂
Answer: b) CH₄
Explanation: Methane (firedamp) accumulates in coal mines, causing explosions.
40. Which fraction of petroleum is used as fuel for aircraft?
a) Kerosene
b) Diesel
c) Petrol
d) Naphtha
Answer: a) Kerosene
Explanation: Aviation turbine fuel (ATF) is a purified form of kerosene.
41. Which of the following is a non-conventional fuel?
a) Biogas
b) Coal
c) Diesel
d) Petrol
Answer: a) Biogas
Explanation: Non-conventional renewable fuels include biogas, solar, wind.
42. The major constituent of coal gas is:
a) CO + CH₄ + H₂
b) N₂ + H₂
c) CO₂ + O₂
d) SO₂ + CH₄
Answer: a) CO + CH₄ + H₂
Explanation: Coal gas is a mixture of CO, CH₄, H₂.
43. Which of the following gases is absent in natural gas?
a) Methane
b) Ethane
c) Carbon dioxide
d) Nitrogen
Answer: d) Nitrogen
Explanation: Natural gas has mainly hydrocarbons with little CO₂ but no nitrogen.
44. What is the calorific value of biogas?
a) 10–15 MJ/m³
b) 20–25 MJ/m³
c) 30–35 MJ/m³
d) 40–45 MJ/m³
Answer: b) 20–25 MJ/m³
Explanation: Biogas has moderate calorific value due to CH₄ + CO₂ composition.
45. Which process is used for separating petroleum into components?
a) Destructive distillation
b) Fractional distillation
c) Sublimation
d) Electrolysis
Answer: b) Fractional distillation
Explanation: Different hydrocarbons separate according to boiling points.
46. LPG is safer than coal because:
a) It is lighter than air and disperses
b) It has no carbon
c) It has no hydrogen
d) It contains nitrogen
Answer: a) It is lighter than air and disperses
Explanation: LPG disperses quickly if leaked, reducing suffocation risk.
47. The “greenhouse gas” present in biogas is:
a) Methane
b) Oxygen
c) Nitrogen
d) Helium
Answer: a) Methane
Explanation: Methane is a potent greenhouse gas and a major component of biogas.
48. Which petroleum product is used in road construction?
a) Paraffin
b) Bitumen
c) Diesel
d) Petrol
Answer: b) Bitumen
Explanation: Bitumen is the residue after fractional distillation of petroleum.
49. What is the main advantage of CNG over petrol and diesel?
a) Lower calorific value
b) Higher pollution
c) Cheaper and cleaner
d) Difficult storage
Answer: c) Cheaper and cleaner
Explanation: CNG burns efficiently with less pollution and is cheaper.
50. Biogas plants use which type of bacteria?
a) Aerobic bacteria
b) Anaerobic methanogens
c) Sulfur bacteria
d) Nitrifying bacteria
Answer: b) Anaerobic methanogens
Explanation: Methanogens (anaerobic bacteria) convert organic matter into methane.
51. Fuels that occur in nature are called:
a) Primary fuels
b) Secondary fuels
c) Synthetic fuels
d) Derived fuels
Answer: a) Primary fuels
Explanation: Primary fuels like coal, wood, and natural gas are found naturally. Secondary fuels like petrol are refined.
52. Petrol, diesel, and LPG are examples of:
a) Primary fuels
b) Secondary fuels
c) Solid fuels
d) Non-combustible fuels
Answer: b) Secondary fuels
Explanation: These are derived by refining crude petroleum → hence secondary fuels.
53. Which is a solid fuel?
a) Kerosene
b) Coal
c) Petrol
d) LPG
Answer: b) Coal
Explanation: Solid fuels include coal, coke, wood, etc.
54. A fuel is said to be efficient when:
a) It has low calorific value
b) It has high calorific value
c) It produces more smoke
d) It burns slowly
Answer: b) It has high calorific value
Explanation: Efficiency of a fuel depends on high energy per unit mass.
55. Which of the following is a liquid fuel?
a) Wood
b) Coke
c) Petrol
d) CNG
Answer: c) Petrol
Explanation: Petrol, diesel, kerosene are liquid fuels.
56. Which of the following is a gaseous fuel?
a) Coal
b) Kerosene
c) LPG
d) Charcoal
Answer: c) LPG
Explanation: LPG, CNG, natural gas are gaseous fuels.
57. Which property of a fuel is most important for its efficiency?
a) Density
b) Calorific value
c) State of matter
d) Color
Answer: b) Calorific value
Explanation: Higher calorific value = more heat released = better efficiency.
58. Which of the following fuels is renewable?
a) Coal
b) Biogas
c) Petrol
d) Diesel
Answer: b) Biogas
Explanation: Biogas is produced from biomass (cow dung, waste) and is renewable.
59. Which gas in fuels causes acid rain when burnt?
a) CO
b) CH₄
c) SO₂
d) H₂
Answer: c) SO₂
Explanation: Sulfur dioxide from coal/diesel combustion forms H₂SO₄ in rain → acid rain.
60. Which fuel is widely used in thermal power plants?
a) Diesel
b) Coal
c) Biogas
d) Hydrogen
Answer: b) Coal
Explanation: Coal is the most common fuel in power generation.
61. Which fuel is better for automobiles due to high octane rating?
a) Coal
b) Petrol
c) Diesel
d) Hydrogen
Answer: b) Petrol
Explanation: Petrol has higher octane number, preventing knocking in engines.
62. Which fuel is commonly used in rural kitchens?
a) Biogas
b) Diesel
c) Coal gas
d) CNG
Answer: a) Biogas
Explanation: Biogas plants in villages provide cheap cooking fuel.
63. Which gas causes global warming the most?
a) Oxygen
b) Methane
c) Carbon dioxide
d) Nitrogen
Answer: c) Carbon dioxide
Explanation: CO₂ is the primary greenhouse gas from fuel burning.
64. Which fuel is preferred for domestic cooking in urban areas?
a) Coal
b) Wood
c) LPG
d) Kerosene
Answer: c) LPG
Explanation: LPG is smokeless, clean, and efficient fuel for kitchens.
65. Which form of energy is stored in fuels?
a) Nuclear energy
b) Thermal energy
c) Chemical energy
d) Electrical energy
Answer: c) Chemical energy
Explanation: Combustion of fuel releases stored chemical energy as heat.
66. Which pollutant is mainly responsible for smog?
a) SO₂
b) NOₓ (oxides of nitrogen)
c) CO₂
d) O₂
Answer: b) NOₓ (oxides of nitrogen)
Explanation: NO and NO₂ react with hydrocarbons to form photochemical smog.
67. Which pollutant from fuels is most dangerous to human health?
a) CO
b) O₂
c) H₂
d) N₂
Answer: a) CO
Explanation: CO binds with hemoglobin to form carboxyhemoglobin → reduces oxygen transport.
68. Which fuel produces the least smoke?
a) Coal
b) Diesel
c) LPG
d) Wood
Answer: c) LPG
Explanation: LPG burns completely and produces negligible smoke.
69. The harmful effect of incomplete combustion of fuels is:
a) More heat
b) Less pollution
c) CO emission
d) Oxygen release
Answer: c) CO emission
Explanation: Incomplete combustion releases toxic CO gas.
70. Which fuel is known as “clean fuel”?
a) Coal
b) Diesel
c) CNG
d) Wood
Answer: c) CNG
Explanation: CNG (methane) produces very low pollution.
71. The calorific value of hydrogen is about:
a) 20 kJ/g
b) 30 kJ/g
c) 50 kJ/g
d) 150 kJ/g
Answer: d) 150 kJ/g
Explanation: Hydrogen has the highest calorific value (~150 kJ/g).
72. Which gas causes respiratory problems when fuels are burnt?
a) N₂
b) CO
c) SO₂
d) H₂O vapor
Answer: c) SO₂
Explanation: Sulfur dioxide causes asthma, bronchitis, and acid rain.
73. Which of the following is a non-polluting fuel?
a) Petrol
b) LPG
c) Hydrogen
d) Diesel
Answer: c) Hydrogen
Explanation: Hydrogen produces only water after combustion.
74. Which property makes LPG suitable as a domestic fuel?
a) High pressure
b) Easy liquefaction & high calorific value
c) Heavy gas
d) Forms smoke
Answer: b) Easy liquefaction & high calorific value
Explanation: LPG can be stored in cylinders and has high energy density.
75. Which fuel causes minimum CO₂ emission per unit energy?
a) Coal
b) Diesel
c) Natural gas
d) Petrol
Answer: c) Natural gas
Explanation: Methane (CH₄) has the highest H:C ratio, giving least CO₂ emission.
76. Which of the following is considered an alternative fuel?
a) Petrol
b) Coal
c) Ethanol
d) Diesel
Answer: c) Ethanol
Explanation: Ethanol (biofuel) is renewable and reduces dependence on fossil fuels.
77. Gasohol is a mixture of:
a) Petrol + Kerosene
b) Petrol + Ethanol
c) Diesel + Ethanol
d) Petrol + Methane
Answer: b) Petrol + Ethanol
Explanation: Gasohol = 90% petrol + 10% ethanol, used in cars.
78. Biodiesel is mainly produced from:
a) Coal tar
b) Vegetable oils and fats
c) Petroleum residues
d) Natural gas
Answer: b) Vegetable oils and fats
Explanation: Biodiesel is made by transesterification of vegetable oils.
79. Which country is the largest producer of ethanol fuel?
a) India
b) USA
c) Brazil
d) China
Answer: c) Brazil
Explanation: Brazil produces ethanol from sugarcane at a large scale.
80. Hydrogen is called a clean fuel because:
a) It has high density
b) It produces only water
c) It produces CO₂
d) It burns with smoke
Answer: b) It produces only water
Explanation: Hydrogen combustion → H₂O (no greenhouse gases).
81. Which is used as a rocket fuel?
a) LPG
b) Hydrogen + Oxygen
c) Coal gas
d) Petrol
Answer: b) Hydrogen + Oxygen
Explanation: Rockets use liquid hydrogen + liquid oxygen.
82. The main disadvantage of hydrogen fuel is:
a) High pollution
b) Low calorific value
c) Storage and transportation difficulty
d) Slow combustion
Answer: c) Storage and transportation difficulty
Explanation: Hydrogen is light, highly flammable, and hard to store.
83. Which fuel is used in fuel cells?
a) Coal
b) Diesel
c) Hydrogen
d) LPG
Answer: c) Hydrogen
Explanation: Fuel cells generate electricity from hydrogen + oxygen.
84. Which renewable fuel can be produced from agricultural waste?
a) CNG
b) Biogas
c) Diesel
d) Petrol
Answer: b) Biogas
Explanation: Anaerobic bacteria decompose agricultural waste → methane.
85. Which of the following is NOT an advantage of CNG?
a) Cheaper than petrol
b) Lower pollution
c) Easy storage at normal pressure
d) High octane rating
Answer: c) Easy storage at normal pressure
Explanation: CNG must be compressed at high pressure → storage is not easy.
86. Which of the following is used as a fuel in nuclear power plants?
a) Thorium-232
b) Uranium-235
c) Plutonium-239
d) All of the above
Answer: d) All of the above
Explanation: U-235, Pu-239, Th-232 are nuclear fuels.
87. The main advantage of nuclear fuel is:
a) No radiation
b) Very high energy per unit mass
c) Cheap construction
d) Easily available
Answer: b) Very high energy per unit mass
Explanation: Nuclear fuels give millions of times more energy than chemical fuels.
88. Which type of energy is obtained from fuels?
a) Mechanical
b) Chemical
c) Nuclear
d) Both b and c
Answer: d) Both b and c
Explanation: Chemical fuels → combustion; nuclear fuels → fission/fusion.
89. Which of the following is a fossil fuel?
a) Biogas
b) Petrol
c) Hydrogen
d) Biodiesel
Answer: b) Petrol
Explanation: Petrol is obtained from crude petroleum.
90. The gas produced in landfills is:
a) CO₂
b) CH₄
c) H₂
d) N₂
Answer: b) CH₄
Explanation: Anaerobic decomposition in landfills produces methane.
91. Which type of fuel is ethanol-blended petrol?
a) Fossil fuel
b) Renewable + non-renewable hybrid
c) Only renewable
d) Only fossil
Answer: b) Renewable + non-renewable hybrid
Explanation: Petrol (fossil) + Ethanol (biofuel) = hybrid fuel.
92. Which of the following is NOT a greenhouse gas?
a) CO₂
b) CH₄
c) SO₂
d) N₂O
Answer: c) SO₂
Explanation: SO₂ causes acid rain, but not a greenhouse gas.
93. Which fuel is considered “carbon neutral”?
a) Biogas
b) Diesel
c) Petrol
d) LPG
Answer: a) Biogas
Explanation: CO₂ released during combustion is balanced by CO₂ absorbed during biomass growth.
94. The main fuel used in gas turbines is:
a) Petrol
b) Diesel
c) Kerosene
d) LPG
Answer: c) Kerosene
Explanation: Aviation turbines use kerosene as jet fuel.
95. Which fuel is mainly used in space shuttles?
a) Diesel
b) Hydrogen + Oxygen
c) LPG
d) Coal gas
Answer: b) Hydrogen + Oxygen
Explanation: Rockets use cryogenic hydrogen and oxygen.
96. The main product formed when natural gas burns completely:
a) CO
b) CO₂ + H₂O
c) SO₂
d) H₂ only
Answer: b) CO₂ + H₂O
Explanation: Complete combustion of methane → CO₂ + H₂O.
97. Which of the following is a disadvantage of fossil fuels?
a) Limited reserves
b) Air pollution
c) Greenhouse effect
d) All of the above
Answer: d) All of the above
Explanation: Fossil fuels cause pollution, climate change, and are non-renewable.
98. The “calorific value” of a fuel represents:
a) Amount of carbon
b) Amount of ash left
c) Heat produced per unit mass
d) Heat absorbed by water
Answer: c) Heat produced per unit mass
Explanation: It measures efficiency of a fuel.
99. The best alternative fuel for future vehicles is:
a) Hydrogen fuel
b) Petrol
c) Coal gas
d) Diesel
Answer: a) Hydrogen fuel
Explanation: Hydrogen is renewable, abundant, and produces no pollution.
100. Which of the following is the main challenge with alternative fuels?
a) Low availability
b) High cost of technology
c) Storage and safety issues
d) All of the above
Answer: d) All of the above
Explanation: Alternative fuels face cost, storage, and technological limitations despite being eco-friendly.