i c engines MCQs – Page 5

Practise focused i c engines questions with marked answers for exam preparation and subject revision.

i c engines Mcqs
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