i c engines Mcqs
51. Diesel engine can work on very lean air fuel ratio of the order of 30 : 1. A petrol engine can also work on such a lean ratio provided__________________?
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A. can not work as it is impossible

B. flywheel size is proper

C. it is properly designed

D. best quality fuel is used

E. engine cooling is stopped

52. Cetane number is determined by comparing the performance of diesel oil with the following hydrocarbons___________________?
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A. ethylene dibromide

B. cetane

C. mixture of cetane with tetra-ethyl lead

D. mixture of aldehydes and ketones

E. mixture of cetane and alphamethyl napthalene
53. Air injection in I.C. engines refers to injection of___________________?
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A. liquid fuel only

B. air only

C. does not exist

D. supercharging

E. liquid fuel and air
54. Air fuel ratio at which a petrol engine can not work is_________________?
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A. 15:01

B. 10:01

C. 20 : 1 and less

D. will work at all ratios

E. 8:01

55. The pour point of diesel oil must be_________________?
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A. lower than the coldest atmospheric temperature at which oil is to be pumped

B. has no such relation

C. more than 100C

D. higher than above

E. none of the above

56. The delay period in petrol engine is of the order of__________________?
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A. 0.002 see

B. 0.01 sec

C. 0.001 sec

D. 0.05 sec

E. 0.1 sec

57. The size of inlet valve of.an engine in comparison to exhaust valve is_________________?
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A. more

B. same

C. less

D. more/less depending on capacity of engine

E. varies from design to design

58. Piston rings are usually made of___________________?
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A. cast iron

B. phosphor bronze

C. carbon steel

D. aluminium

E. babbitt

59. Sulphur content in diesel oil should not be more than_________________?
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A. 0.01%

B. 5%

C. 10%

D. 0.10%

E. 1%

60. The specific fuel consumption per BH hour for a petrol engine is approximately__________________?
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A. 0.25 kg

B. 0.3kg

C. 0.35 kg

D. 0.15 kg

E. 0.2 kg

61. Fuel oil consumption guarantees for I .C. engine are usually based on__________________?
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A. high heat value of oil

B. net calorific value of oil

C. all of the above

D. calorific value of fuel

E. low heat value of oil

62. The term scavenging is generally associated with______________________?
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A. high efficiency engines

B. 4-stroke cycle engines

C. 2-stroke cycle engines

D. aeroplane engines

E. diesel engines

63. Ignition timing of a multicylider petrol engine can be adjusted by_________________?
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A. adjusting the spark plug gap

B. adjusting ignition coil position

C. rotating the distributor

D. delaying the spark by increasing capacitor in ignition circuit

E. rotating the crank

64. A hmh flame speed is obtained in diesel engine when air fuel ratio is_______________?
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A. about 10% lean mixture

B. about 3-5% rich mixture

C. about 10% rich mixture

D. uniform throughout the mixture

E. chemically correct mixture

65. The function of a fuel pump in a petrol pump is to______________________?
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A. inject fuel in cylinder

B. does not exist

C. supply fuel when carburettor fails

D. pump fuel so that it reaches carburettor (to improve thermal efficiency)
66. Pick up the false statement ?
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A. S.I. engines are quality-governed engines

B. Theoretically correct mixture of air am petrol is approximately 15 : 1

C. High speed compression engines operate on dual combustion cycle

D. Diesel engines are compression ignition engines

E. Thermal efficiency of diesel engine i about 34%

67. The efficiency of I.C. engines normally is of the order of_________________?
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A. 15-20%

B. 20-25%

C. 35-50%

D. 25-30%

E. 30-35%
68. In isochronous governing, speed droop is_______________?
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A. 5%

B. 30%

C. 100%

D. 50%

E. 1%.

69. Piston rings are plated with chromium,cadmium or phosphate in order to__________________?
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A. improve heat transfer

B. prevent clogging

C. improve surface finish

D. reduce wear and eliminate scuffing

E. reduce cost

70. Octane number is determined by comparing the performance of the petrol with the following hydrocarbons__________________?
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A. iso-octane

B. alpha methyl napthalene

C. mixture of paraffins and aromatics

D. mixture of normal heptane and iso-oc-tane

E. mixture of methane and ethane

71. The thermal efficiency of a diesel engine is of the order of_________________?
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A. 92%

B. 68%

C. 25%.

D. 52%

E. 34%
72. The most popular firing order in case of four cylinder in-line I.C. engine is__________________?
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A. 1-2-3-4

B. 1-4-2-3

C. 1-3-4-

D. 1-2-4-3

E. 1-3-2-4
73. The operation of forcing additional air under pressure in the engine cylinder is known as________________?
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A. scavenging

B. pre-ignition

C. dissociation and carburretion of fuel

D. supercharging

E. turbulence

74. The calorific value of gaseous fuels is expressed in terms of__________________?
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A. kcal

B. kcal/m2

C. kcal/kg

D. all of the above

E. kcal/m
75. Exhaust pipes of engines are covered with insulating marterial in order to_________________?
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A. conserve heat

B. reduce formation of condenstae

C. reduce heat transfer to the engine room

D. keep the exhaust pipes warm

E. increase engine efficiency

76. In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of____________________?
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A. 150CPC

B. 500C

C. 1000C

D. 250C

E. 2000C

77. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the________________?
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A. exhaust will be smoky

B. exhaust temperature will be high

C. engine starts overheating

D. scavenging occurs

E. piston rings would stick into piston grooves

78. In loop scavenging, the top of the piston is________________?
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A. slanted

B. depressed

C. flat

D. contoured

E. convex shaped

79. The maximum temperature in the I.C. engine cylinder is of the order of ________________?
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A. 1000- 1500C

B. 1500-2000C

C. 2000-2500C

D. 500- 1000C

E. 2500-3000C

80. The specific gravity of diesel oil Is_________________?
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A. 0.7

B. 1.25

C. 0.5

D. 0.85

E. 1

81. Freezing temperature of petrol is usually__________________?
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A. less than 30C

B. 0C

C. 10C

D. less than 273C

E. 10C

82. Compression ratio of LC. engines is ___________________?
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A. cylinder volume/swept volume

B. the ratio of volumes of air in cylinder before compression stroke and after compression stroke

C. swept volume/cylinder volume

D. volume displaced by piston per stroke and clearance volume in cylinder

E. ratio of pressure after compression and before compression

83. As the number of cylinders in multi-cylinder engine increases, the power to weight ratio_______________?
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A. Decreases upto a limit and then increases

B. Decreases

C. Remains same

D. Increases

84. Scavenging is usually done to increase__________________?
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A. thermal efficiency

B. speed

C. fuel consumption

D. power output

E. all of the above

85. The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed____________________?
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A. 80C

B. 320C

C. 180C

D. 240C

E. 120C

86. An engine has a normal speed of 960 r.p.m. and no load speed of 1000 r.p.m. The speed droop of governor will be about___________________?
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A. 4%

B. 8%

C. 4%

D. 1%.

E. 2%

87. A diesel engine as compared to petrol engine (both running ar rated load) is ____________________?
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A. equally efficient

B. less efficient

C. more efficient

D. other factors will decide it

E. unperdictable

88. For same power and same speed, the flywheel of a four stroke engine as compared to two-stroke I.C. engine will be________________?
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A. unpredictable

B. dependent on other engine parameters

C. smaller

D. same size

E. bigger
89. The reason for supercharging in any engine is to________________?
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A. none of the above

B. reduce weight and bulk for a given out-put

C. increase efficiency

D. increase power

E. effect fuel economy

90. The knock in diesel engine occurs due to____________________?
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A. delayed burning of the first part of the charge

B. reduction of delay period

C. instantaneous and rapid burning of the first part of the charge

D. all ot the above

E. instantaneous atuo iginition of last part of charge

91. Diesel fuel, compared to petrol is_________________?
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A. just about the same difficult to ignite

B. none of the above

C. less difficult to ignite

D. highly ignitable

E. more difficult to ignite
92. The ratio of useful power; engine friction exhaust gas losses; cooling water, air and oil losses for a diesel engine is of the order of____________________?
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A. 40:30:15:15

B. 25:5:35:35

C. 25:35:5:35

D. 5:25:30:50

E. 25:5:10:60

93. If the intake air temperature of I.C. engine increases, its efficiency will_________________?
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A. depend on other factors

B. unpredictable

C. remain same

D. decrease

E. increase

94. Auto-ignition temperature is____________________?
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A. indicated by 50% distillation temperature

B. temperature at which it solidifies or congeals

C. that at which it catches fire without external aid

D. indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

E. minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

95. A stoichiometric air-fuel ratio is______________________?
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A. lean mixture

B. chemically correct mixture

C. the ratio used at full rated parameters

D. rich mixture for idling

E. rich mixture for over loads

96. In the opposed piston diesel engine, the combustion chamber is located________________?
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A. any when

B. between the pistons

C. there is no such criterion

D. above the piston (/;) below the piston

97. Crankcase explosion in I.C. engines usuall occurs as ___________________?
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A. first a mild explosion followed by a bi explosion

B. first a big explosion followed by a mil explosion

C. both mild and big explosions occi simultaneously

D. never occurs

E. unpredictable

98. Power impulses from an I.C. engine are somoothed out by__________________?
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A. gear box

B. governor

C. timing spark properly

D. flywheel

E. crank shaft

99. The ash content in diesel oil should bot be more than_______________?
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A. 0.01%

B. 0.10%

C. 5%

D. 0.001%

E. 1%

100. Which of the following medium is compressed in a Diesel engine cylinder __________________?
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A. air and lub oil

B. air, fuel and lub oil

C. air and fuel

D. air aione

E. fuel alone