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240 Important Internal Combustion Engines MCQ Question and Answer | PDF Free Download

Internal Combustion Engines MCQ Question and Answer PDF Free Download

1.The size of inlet valve of an engine in comparison to exhaust valve is

  • AMore
  • BLess
  • CSame
  • DMore/less depending on capacity of engine
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Correct Answer : (A)

More

Explanation:

2.The thermal efficiency of diesel engines is about

  • A15%
  • B30%
  • C50%
  • D70%
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Correct Answer : (D)

70%

Explanation:

3.The thermal efficiency of petrol and gas engines is about

  • A15%
  • B30%
  • C50%
  • D70%
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Correct Answer : (B)

30%

Explanation:

4.The thermodynamic cycle on which the petrol engine works, is

  • AOtto cycle
  • BJoule cycle
  • CRankine cycle
  • DStirling cycle
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Correct Answer : (A)

Otto cycle

Explanation:

5.In loop scavenging, the top of the piston is

  • AFlat
  • BContoured
  • CSlanted
  • DDepressed
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Correct Answer : (B)

Contoured

Explanation:

6.In a four stroke cycle engine, the sequence of operations is

  • ASuction, compression, expansion and exhaust
  • BSuction, expansion, compression and exhaust
  • CExpansion, compression, suction and exhaust
  • DCompression, expansion, suction and exhaust
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Correct Answer : (A)

Suction, compression, expansion and exhaust

Explanation:

7.Iso-octane (C₈H₁₈) has octane number of

  • A0
  • B50
  • C100
  • D150
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Correct Answer : (C)

100

Explanation:

8.The _________ engines can work on very lean mixture of fuel.

  • ASpark ignition
  • BCompression ignition
  • CBoth (A) and (B)
  • DNone of these
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Correct Answer : (B)

Compression ignition

Explanation:

9.The output of a diesel engine can be increased without increasing the engine revolution or size in following way

  • AFeeding more fuel
  • BHeating incoming air
  • CScavenging
  • DSupercharging
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Correct Answer : (D)

Supercharging

Explanation:

10.Which of the following does not relate to a spark ignition engine?

  • AIgnition coil
  • BSpark plug
  • CCarburettor
  • DFuel injector
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Correct Answer : (D)

Fuel injector

Explanation:

11.Which of the following does not relate to a compression ignition engine?

  • AFuel pump
  • BFuel injector
  • CGovernor
  • DCarburettor
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Correct Answer : (D)

Carburettor

Explanation:

12.Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine?

  • AInlet valve closing after bottom dead center
  • BInlet valve closing before bottom dead center
  • CInlet valve opening before top dead center
  • DExhaust valve closing after top dead center
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Correct Answer : (B)

Inlet valve closing before bottom dead center

Explanation:

13.When crude oil is heated, then which of the following hydrocarbon is given off first?

  • AKerosene
  • BGasoline
  • CParaffin
  • DNatural gas
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Correct Answer : (D)

Natural gas

Explanation:

14.The turbine of the turboprop engine is __________ that of the turbojet engine.

  • ASame as
  • BSmaller than
  • CBigger than
  • DNone of these
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Correct Answer : (C)

Bigger than

Explanation:

15.The inlet valve of a four stroke cycle internal combustion engine remains open for

  • A130°
  • B180°
  • C230°
  • D270°
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Correct Answer : (C)

230°

Explanation:

16.In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have

  • ALow density
  • BLow temperature
  • CLong ignition delay
  • DAll of these
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Correct Answer : (D)

All of these

Explanation:

17.The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called

  • AMechanical efficiency
  • BOverall efficiency
  • CVolumetric efficiency
  • DRelative efficiency
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Correct Answer : (C)

Volumetric efficiency

Explanation:

18.The actual volume of fresh charge admitted in 4-stroke petrol engine is

  • AEqual to stroke volume
  • BEqual to stroke volume and clearance volume
  • CLess than stroke volume
  • DMore than stroke volume
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Correct Answer : (C)

Less than stroke volume

Explanation:

19.The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be

  • AHigher
  • BLower
  • CRemain unaffected
  • DNone of the above
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Correct Answer : (A)

Higher

Explanation:

20.A two stroke cycle engine gives ________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed.

  • AHalf
  • BSame
  • CDouble
  • DFour times
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Correct Answer : (C)

Double

Explanation: