i c engines MCQs – Page 7

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

i c engines Mcqs

121. The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be________________?
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A. remain unaffected

B. higher

C. none of the above

D. lower

E. unpredictable

122. Petrol is distilled at a temperature in range of__________________?
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A. 450-550C

B. 220-350C

C. 350-450C

D. 65 220C

E. 30 65C

123. Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power_____________?
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A. upto 75%

B. upto 25%

C. upto 35%

D. upto 50%

E. upto 100%.

124. As a result of detonation in an I.C. engine, following parameter attains very high value _____________________?
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A. peak temperature

B. rate of rise of pressure

C. rate of rise of temperature

D. peak pressure

E. rate of rise of horse-power

125. The air-fuel ratio of the petrol engine is controlled by__________________?
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A. injector

B. governor

C. fuel pump

D. carburettor

E. scavenging

126. For low speed operation or for idling in petrol engines, the engine requirements are for_______________?
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A. lean mixture

B. rich mixture

C. theoretically correct mixture

D. lean/rich mixture depending upon capacity of engine

E. any type of mixture

127. The top piston ring nearer to the piston crown is known as_____________________?
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A. leading ring

B. oil ring

C. compression ring

D. scrapper ring

E. groove ring

128. In a typical medium speed 4-stroke cycle diesel engine the inlet valve_____________________?
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A. may open or close anywhere

B. opens at top dead center and closes at bottom dead center

C. opens at 20 before top dead center and closes at 35 after the bottom dead center

D. opens at 10 after top dead center and closes 20 before the bottom dead center

E. remains open for 200.

129. Air fuel ratio for idling speed of a petrol engine is approximately_________________?
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A. 10:1

B. 15:01

C. 5:01

D. 1:01

E. 20:01

130. Compression loss in I.C engines occurs due to_________________?
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A. increase in clearance volume caused b bearing-bushing wear

B. clogged air-inlet slots

C. leaking piston rings

D. all of the above

E. use of thick head gasket

131. Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows ________________?
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A. using additives in the fuel

B. engine derating i.e. reducing the maxi-mum flow of fuel

C. adherence to proper fuel specification

D. avoidance of overloading

E. increasing the compression ratio

132. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is__________________?
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A. unpredictable

B. less

C. more or less depending on power rating

D. more

E. same

133. Combustion in compression ignition engines is____________________?
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A. homogeneous

B. heterogeneous

C. both A. and B.

D. laminar

E. turbulent

134. For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of _________________?
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A. 18:01

B. 9:01

C. 20:01

D. 15:01

E. 12 : 1

135. Ignition lag is__________________?
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A. time before actual fuel injection and the pump plunger starts to pump fuel

B. time corresponding to actual injection and top dead center

C. none of the above

D. the time taken by fuel after injection (before top dead center) to reach upto auto-ignition temperature

E. time corresopnding to actual ingition and top dead center

136. Volatility of diesel fuel oil is_________________?
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A. 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

B. temperature at which it flows easily

C. temperature at which it solidifies or congeals

D. it catches fire without external aid

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

137. Which of the following is the lightest and most volatile liquid fuel________________?
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A. gasoline

B. diesel

C. lub oil

D. kerosene

E. fuel oil

138. In a typical medium speed 4 stroke cycle diesel engine_______________?
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A. exhaust valve opens at bottom dead center and closes at top dead center

B. exhaust valve opens at 35 before bot-tom dead center and closes at 20 after top dead center

C. exhaust valve opens just after bottom dead center and closes just before top dead center

D. may open and close anywhere

E. none of the above is true

139. The fuel in diesel engine is normally injected at pressure of_________________?
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A. 20-25 kg/cm2

B. 150-250 kg/cm2

C. 90-130 kg/cm2

D. 60-80 kg/cm2

E. 5-10 kg/cm2

140. The output of a diesel engine can be increased without increasing the engine revolution or size in following way_________________?
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A. increasing flywheel size

B. supercharging

C. scavenging

D. heating incoming air

E. feeding more fuel

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