i c engines Mcqs
101. In a cycle, the spark lasts roughly for ____________________?
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A. 0.01 sec

B. 0.0001 sec

C. 0.001 sec

D. 1 sec

E. 0.1 sec

102. In order to prevent formation of carbon on the injector, the temperature of nozzle tip should be__________________?
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A. between 250 300C

B. less than 100C

C. between 100-250C

D. between 400 500C

E. between 500 1000C

103. To reduce the possibility of knock in the C.I. engines, the first elements of fuel and air should have_______________?
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A. reactive mixture

B. high temperature

C. high density

D. short delay

E. all of the above
104. A fuel will detonate less if it has___________________?
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A. proper self ignition temperature

B. lower self ignition temperature

C. none of the above

D. higher self ignition temperature

E. self ingition temperature has nothing to do with detonation

106. Flash point of fuel oil is __________________?
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A. temperature at which it catches fire without external aid

B. temperature at which it solidifies or congeals

C. minimum temperature to which1 oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

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

E. none of the above

107. Scavenging air in diesel engine means___________________?
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A. burnt air containing products of combustion

B. air used for forcing burnt gases out of engines cylinder during the exhaust period

C. forced air for cooling cylinder

D. air fuel mixture

E. air used for combustion sent under pres-sure

108. Kerosene is distilled at________________?
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A. 350 450C

B. 30 65C

C. 220 350C

D. 450-550C

E. 65 220C

109. Fuel consumption with increase in back pressure will________________?
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A. depend on other factors

B. increase

C. decrease

D. remain unaffected

E. none of the above

111. The function of a distributor in an automobile is to__________________?
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A. regulate power

B. distribute charge, equally to all the cylinders

C. feed lub oil to all moving parts

D. inject fuel at appropriate time

E. time the spark
112. In open combustion chamber in diesel engines____________________?
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A. fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat

B. the shape and layout of the piston crown, the inlet port, and the valve produce the turbulent effect on fuel mixture

C. fuel is injected at atmospheric pressure

D. there are no valves.

E. only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency mixes thoroughly into main cylinder charge

113. It the temperature of intake air in IC engines is lowered, then its efficiency will_______________________?
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A. decrease upto certain limit and then in-crease

B. decrease

C. increase upto certain limit and then decrease

D. increase

E. remain same

114. According to Recardos theory, detonation occurs due to______________________?
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A. none of the above

B. instantaneous auto-ignition of last part of charge to be burnt

C. improper mixing of air and fuel

D. self ignition temperature has nothing to do with detonation

E. improper combustion

115. The essential equipment for producing high vlotage for sparking in petrol engines with battery is_______________?
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A. ignition coil, contact breaker and con-denser

B. ignition coil

C. ignition coil and distributor

D. ignition coil and contact breaker

E. ignition coil and condenser

116. Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads________________?
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A. the engine is rarely operated

B. the friction is unpredictable

C. none of the above

D. the small difference in cooling water temperature or in internal friction has a disproportionate effect

E. the friction is high

118. An engine indicator is used to determine the following___________________?
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A. volume of cylinder

B. speed

C. BHP

D. temperature

E. m.e.p. and I.H.P.
119. A heat engine utilises the_________________?
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A. mean heat value of oil

B. calorific value of oil

C. low heat value of

D. high heat value of oil

E. all of the above

120. Ethyl fluid is used_______________________?
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A. as a defrosting agent

B. as a superior type of fluid compared to others

C. to increase the cetane rating of the fuel

D. to increase the octane rating of the fuel

E. to improve lubricating quality of fuel

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

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.

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

B. heterogeneous

C. both A. and B.

D. laminar

E. turbulent

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
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

142. Method of governing used in diesel engine is__________________?
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A. nit and miss governing

B. combined governing

C. quantity governing

D. quality governing

E. partial governing

143. The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will___________________?
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A. may increase or decrease depending on other factors

B. be independent

C. none of the above

D. increase

E. decrease
144. A diesel engine has_________________?
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A. 3 valves

B. 1 valve

C. 2 valves

D. no valve

E. 4 valves

145. The magneto in an automobile is basically__________________?
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A. transformer

B. capacitor

C. a.c. generator

D. d.c. generator

E. magnetic circuit

146. Which is more viscous lub oil_________________?
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A. SAE 80

B. SAE 4

C. SAE 50

D. SEA 30

E. SAE 70

147. For the same power developed in I.C. engines, the cheaper system is_____________?
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A. supercharged

B. naturally aspirated

C. centrifugal pump

D. turbo charger

E. none of the above

148. Pick up the wrong statement about supercharging __________________?
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A. supercharging is essential in aircraft engines

B. there can be limited supercharging in petrol engines because of detonation

C. supercharging reduces knocking in diesel engines

D. supercharging at high altitudes is essential

E. supercharging results in fuel economy
149. In petrol engine, increase of cooling water temperature will_________________?
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A. unpredictable

B. increase or decrease knocking tendency depedning on strength and time of spark

C. not affect the knocking tendency

D. decrease the knocking tendecny

E. increase the knocking tendency
150. If diesel is fed by mistake in the oil tank of a petrol engien, then engine will________________?
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A. knock

B. detonate

C. give lot of smoke

D. run for some time and then stop

E. not run