i c engines MCQs – Page 3

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

i c engines Mcqs
41. Which is correct statement about reaction time for autoignition of fuel and the fuel air ratio__________________?
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A. non of the above

B. chemically correct mixture has mini-mum reaction time

C. rich mixture has high reaction time

D. all of the above

E. lean mixture has high reaction time

42. The system of lubrication used for motor cycles and scooters is by________________?
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A. forced lubrication system

B. mixing about 5% lub oil with petrol

C. applying grease under pressure

D. wet sump method

E. splash lubrication

43. The thermal efficiency of a petrol engine of two stroke with crank case scavenging as compared to four stroke petrol engine with same comperssion ratio will be_____________________?
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A. depends on size of engine

B. same

C. higher

D. unpredictable.

E. lower
44. The air-fuel ratio in petrol engines-is controlled by__________________?
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A. carburettion

B. controlling valve opening/closing

C. scavenging and supercharging

D. injection

E. governing

45. In the crankcase method of scavenging, the air pressure is produced by_________________?
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A. movement of engine piston

B. reciprocating pump

C. centrifugal pump

D. natural aspirator

E. supercharger

46. In a diesel engine, the fuel is ignited by___________________?
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A. ignition

B. injected fuel

C. spark

D. heat resulting from compressing air that is supplied for combustion

E. combustion chamber

47. The self-ignition temperature of diesel oil compared to petrol is_________________?
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A. depends on quality of fuel

B. lower

C. higher

D. same

E. unpredictable

48. Cetane___________________?
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A. has 100 cetane number

B. has zero cetane number

C. is a straight chain paraffin

D. determines the efficiency of an I.C. engine

E. helps detonation

49. Solid injection in I.C. engines refers to injection of________________?
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A. liquid fuel only

B. solid fuel

C. does not exist

D. liquid fuel and air

E. solid fuel and air

50. The termal efficiency of a petrol engine at design load is around_________________?
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A. 40%

B. 15%.

C. 50%

D. 30%

E. 90%

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