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Mechanical Engineering MCQs with Explanations

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251Mechanical EngineeringMedium

Theoretically, the following engine should have maximum efficiency________?

Agas engine

B2-stroke S.I. engine

C4-stroke C.I. engine

D4-stroke S.I. engine

Esteam engine

Correct answer

C. 4-stroke C.I. engine

Explanation

The correct answer is 4-stroke C.I. engine.

252Mechanical EngineeringMedium

Hot air standard diesel cycle efficiency with increase in value of C„________?

Aremains unaffected

Bdecreases

Cincreases

Ddepends on other factors

Eunpredictable

Correct answer

B. decreases

Explanation

The correct answer is decreases.

253Mechanical EngineeringMedium

The dry saturated steam at very low pressure, (5-10 kg/cm2) when throttled to atmosphere will become________?

Adry

Bwet

Csuperheated

Dnone of the above

Eremain dry satruated

Correct answer

C. superheated

Explanation

The correct answer is superheated.

254Mechanical EngineeringMedium

On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by________?

Ahorizontal straight line

Bcurved line

Cvertical straight line

Dnone of the above

Estraight inclined line

Correct answer

A. horizontal straight line

Explanation

The correct answer is horizontal straight line.

255Mechanical EngineeringMedium

Volumetric efficiency of a compressor with clearance volume ________?

Aunpredictable

Bmay increase/decrease depending on compressor capacity

Cin not dependent upon compression ratio

Ddecreases with increase in compression ratio

Eincreases with increase in compression ratio

Correct answer

D. decreases with increase in compression ratio

Explanation

The correct answer is decreases with increase in compression ratio.

256Mechanical EngineeringMedium

For a thermodynamic process to be reversible, the temperature difference between hot body and working substance should be________?

Athere is no such criterion

Bmaximum

Czero

Dinfinity

Eminimum

Correct answer

C. zero

Explanation

The correct answer is zero.

257Mechanical EngineeringMedium

The major axis of elliptical manholes on the shell should be provided________?

Acircumferentially

Blongitudinally

Cvertically

Danywhere

Eon dished end

Correct answer

A. circumferentially

Explanation

The correct answer is circumferentially.

258Mechanical EngineeringMedium

The equivalent evaporation of a boiler is a measure to compare ________?

Athe given boiler with the model

Bthe two different boilers of the same make

Ctwo boilers of same make but operaing under different conditions

Dtwo different makes of boilers operat¬ing under the same operating conditions

Eany type of boilers operating under any conditions

Correct answer

E. any type of boilers operating under any conditions

Explanation

The correct answer is any type of boilers operating under any conditions.

259Mechanical EngineeringMedium

The patrol is distilled at a temperature from :

A65° to 220°

B15° to 120°

C6° to 20°

D220° to 345°

Correct answer

A. 65° to 220°

Explanation

The correct answer is 65° to 220°.

260Mechanical EngineeringMedium

If a certain amount of dry ice is mixed with same amount of water at 80°C, the final temperature of mixture will be________?

A20°C

B80°C

C60°C

D40°C

E0°C

Correct answer

E. 0°C

Explanation

The correct answer is 0°C.

Volumetric efficiency of a compressor with clearance volume ________?

Aunpredictable

Bmay increase/decrease depending on compressor capacity

Cin not dependent upon compression ratio

Ddecreases with increase in compression ratio

Eincreases with increase in compression ratio

Correct answer

D. decreases with increase in compression ratio

Explanation

The correct answer is decreases with increase in compression ratio.

The equivalent evaporation of a boiler is a measure to compare ________?

Athe given boiler with the model

Bthe two different boilers of the same make

Ctwo boilers of same make but operaing under different conditions

Dtwo different makes of boilers operat¬ing under the same operating conditions

Eany type of boilers operating under any conditions

Correct answer

E. any type of boilers operating under any conditions

Explanation

The correct answer is any type of boilers operating under any conditions.