I.C. Engines Mcqs

This set of Mechanical engineering Multiple Choice Questions & Answers (MCQs) focuses on study of “ Integrated Circuit Engines ”. These questions are chosen from a collection of most authoritative and best reference books on Mechanical engineering. Our aim is to prepare an individual for competitive exams like NTS, GAT, ECAT, University and College entrance exams, Jobs and interviews. One should practice our MCQS to assimilate I.C. Engines comprehensively.

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32.
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__________________?

It is properly designed

Best quality fuel is used

Can not work as it is impossible

Flywheel size is proper

33.
The knock in diesel engine occurs due to____________________?

Instantaneous and rapid burning of the first part of the charge

Instantaneous atuo iginition of last part of charge

Delayed burning of the first part of the charge

Reduction of delay period

34.
The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft___________________?

1/2

1

2

4

35.
Scavenging air in diesel engine means___________________?

Air used for combustion sent under pres-sure

Forced air for cooling cylinder

Burnt air containing products of combustion

Air used for forcing burnt gases out of engine’s cylinder during the exhaust period

36.
Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged ?

Yes

No

To some extent

Unpredictable

37.
The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is__________________?

Same

Less

More

More or less depending on power rating

38.
In a diesel engine, the fuel is ignited by___________________?

Spark

Injected fuel

Heat resulting from compressing air that is supplied for combustion

Ignition

39.
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called__________________?

Net efficiency

Efficiency ratio

Relative efficiency

Overall efficiency

40.
If the intake air temperature of I.C. engine increases, its efficiency will_________________?

Increase

Decrease

Remain same

Unpredictable

41.
An engine indicator is used to determine the following___________________?

Speed

Temperature

Volume of cylinder

M.e.p. and I.H.P.

42.
In a typical medium speed 4-stroke cycle diesel engine the inlet valve_____________________?

Opens at 20° before top dead center and closes at 35° after the bottom dead center

Opens at top dead center and closes at bottom dead center

Opens at 10° after top dead center and closes 20° before the bottom dead center

May open or close anywhere

43.
The pressure at the end of compression in the case of diesel engine is of the order of___________________?

6 kg/cm

12kg/cmz

20 kg/cmz

27.5 kg/cmz

44.
If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be________________?

2%

4%

8%

14%

45.
The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will___________________?

Increase

Decrease

Be independent

May increase or decrease depending on other factors

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