4791 + Mcqs in Mechanical Engineering McqOptions

1.	A nuclear power plant differs from a conventional steam power station only in the steam generating part.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

2.	In a four stroke engine, the working cycle is completed in
A.	one revolution of the crankshaft
B.	two revolutions of the crankshaft
C.	three revolutions of the crankshaft
D.	four revolutions of the crankshaft
Answer» C. three revolutions of the crankshaft

Discussion

3.	Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine ?
A.	inlet valve closing after bottom dead centre
B.	inlet valve closing before bottom dead centre
C.	inlet valve opening before top dead centre
D.	exhaust valve closing after top dead centre
Answer» C. inlet valve opening before top dead centre

Discussion

4.	The efficiency of roots blower __________ with the increase in pressure ratio.
A.	decreases
B.	increases
C.	does not change
Answer» B. increases

Discussion

5.	The operation of lifts, rams and pumps make use of compressed air.
A.	Yes
B.	No
Answer» B. No

Discussion

6.	In a compressed air system, the temperature of air discharged from the air motor is __________ than the initial compressor intake temperature.
A.	more
B.	less
Answer» C.

Discussion

7.	Which of the following statement is correct relating to rocket engines ?
A.	The combustion chamber in a rocket engine is directly analogous to the reservoir of a super sonic wind tunnel
B.	The stagnation conditions exist at the combustion chamber
C.	The exit velocities of exhaust gases are much higher than those in jet engine
D.	all of the above
Answer» E.

Discussion

8.	In reciprocating air compressors, isothermal efficiency is used for all sorts of calculations.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

9.	Euler's equation can be used for
A.	radial flow compressors
B.	axial flow compressors
C.	pumps
D.	all of these
Answer» E.

Discussion

10.	A jet engine has
A.	no propeller
B.	propeller in front
C.	propeller at back
D.	propeller on the top
Answer» B. propeller in front

Discussion

11.	A rocket engine uses __________ for the combustion of its fuel.
A.	surrounding air
B.	compressed atmospheric air
C.	its own oxygen
D.	none of these
Answer» D. none of these

Discussion

12.	Free air is the air at atmospheric conditions at any specific location.
A.	True
B.	False
Answer» B. False

Discussion

13.	The perfect intercooling, in multistage compression, means that the temperature of air at inlet to subsequent stages is equal to the initial temperature.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

14.	A gas turbine used in air-craft should have low weight and small frontal area.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

15.	A closed cycle gas turbine works on
A.	Carnot cycle
B.	Rankine cycle
C.	Ericsson cycle
D.	Joule cycle
Answer» E.

Discussion

16.	Air motors work on the cycle which is the reverse of the reciprocating air compressor cycle.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

17.	The axial flow compressor is preferred in air-craft gas turbines because of
A.	low frontal area
B.	higher thrust
C.	high pressure rise
D.	none of these
Answer» B. higher thrust

Discussion

18.	Which of the following statement is correct as regard to centrifugal compressors?
A.	The flow of air is parallel to the axis of the compressor.
B.	The static pressure of air in the impeller increases in order to provide centripetal force on the air.
C.	The impeller rotates at high speeds.
D.	The maximum efficiency is higher than multi-stage axial flow compressors.
Answer» C. The impeller rotates at high speeds.

Discussion

19.	The ratio of the net work obtained from the gas turbine plant to the turbine work is known as
A.	compression ratio
B.	work ratio
C.	pressure ratio
D.	none of these
Answer» C. pressure ratio

Discussion

20.	The clearance, in a single stage, single acting reciprocating air compressor does not effect the workdone on the air and the power required for compressing the air.
A.	True
B.	False
Answer» B. False

Discussion

21.	The process, which causes the air to enter the impeller blades of a centrifugal compressor at __________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.
A.	reduced
B.	increased
Answer» B. increased

Discussion

22.	A closed cycle gas turbine consists of a
A.	compressor
B.	heating chamber
C.	cooling chamber
D.	all of these
Answer» E.

Discussion

23.	A receiver in compressor installations is used to damp pressure waves in compressor discharge.
A.	Yes
B.	No
Answer» B. No

Discussion

24.	In jet propulsion power unit, the inlet duct of diverging shape is used for converting kinetic energy of air into pressure energy.
A.	True
B.	False
Answer» B. False

Discussion

25.	For maximum work, the reheating should be done to an intermediate pressure of (where p1 = Maximum pressure, and p2 = Minimum pressure)
A.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/380-170-1.png">
B.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/380-170-2.png">
C.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/380-170-3.png">
D.	<span class="root"><i>p</i><sub>1</sub><i>p</i><sub>2</sub></span>
Answer» E.

Discussion

26.	The temperature of air at the beginning of the compression stroke is __________ the atmospheric temperature.
A.	equal to
B.	less than
C.	more than
Answer» D.

Discussion

27.	The pressure ratio in a centrifugal compressor can be increased by increasing the tip speed and lowering the inlet temperature.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

28.	Gas turbine as compared to internal combustion engine
A.	can be driven at a very high speed
B.	produces uniform torque
C.	has more efficiency
D.	all of these
Answer» E.

Discussion

29.	A two stroke cycle engine occupies larger floor area than a four stroke cycle engine.
A.	Yes
B.	No
Answer» C.

Discussion

30.	The compressor efficiency is defined as the ratio of volume of free air delivery per stroke to the swept volume of the piston.
A.	Correct
B.	Incorrect
Answer» C.

Discussion

31.	In a four stroke cycle petrol engine, , the compression
A.	starts at 40 after bottom dead centre and ends at 30 before top dead centre
B.	starts at 40 before bottom dead centre and ends at 30 after bottom dead centre
C.	starts at bottom dead centre and ends at top dead centre
D.	may start and end anywhere
Answer» B. starts at 40 before bottom dead centre and ends at 30 after bottom dead centre

Discussion

32.	In a gas turbine, air is obtained from the atmosphere and compressed in an air compressor.
A.	True
B.	False
Answer» B. False

Discussion

33.	The overall efficiency is defined as the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.
A.	True
B.	False
Answer» B. False

Discussion

34.	The reflectivity of a reflector is defined as the fraction of neutrons entering the reflector which are returned to the core.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

35.	Reflector in nuclear power plants is used to reflect neutrons back into the active core.
A.	True
B.	False
Answer» B. False

Discussion

36.	The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
A.	Morse test
B.	prony brake test
C.	motoring test
D.	heat balance test
Answer» B. prony brake test

Discussion

37.	The turbine of the turbo-prop engine is __________ that of the turbo-jet engine.
A.	same as
B.	smaller than
C.	bigger than
Answer» D.

Discussion

38.	The pressure at the end of compression, in petrol engines, is approximately
A.	10 bar
B.	20 bar
C.	25 bar
D.	35 bar
Answer» B. 20 bar

Discussion

39.	The sparking in a petrol engine increases pressure and temperature of the products of combustion, but the volume remains constant.
A.	Yes
B.	No
Answer» B. No

Discussion

40.	A higher compression ratio causes
A.	pre-ignition
B.	increase in detonation
C.	an acceleration in the rate of combustion
D.	any one of these
Answer» E.

Discussion

41.	A diesel engine is __________ as compared to petrol engine, both running at rated load.
A.	equally efficient
B.	less efficient
C.	more efficient
Answer» D.

Discussion

42.	In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
A.	equal to
B.	below
C.	above
Answer» C. above

Discussion

43.	The combustion in compression ignition engines is
A.	homogeneous
B.	hetrogeneous
C.	both (a) and (b)
D.	none of these
Answer» C. both (a) and (b)

Discussion

44.	Which of the following fuel detonates readily ?
A.	Benzene
B.	Iso-octane
C.	Normal heptane
D.	Alcohol
Answer» D. Alcohol

Discussion

45.	The inlet valve of a four stroke cycle internal combustion engine remains open for
A.	130
B.	180
C.	230
D.	270
Answer» D. 270

Discussion

46.	The cetane (C16H34) which is a straight chain paraffin is assigned a cetane number of
A.	0
B.	50
C.	100
D.	120
Answer» D. 120

Discussion

47.	Morse test is used to determine the I.P. of a
A.	single cylinder petrol engine
B.	four stroke engine
C.	single cylinder diesel engine
D.	multi-cylinder engine
Answer» E.

Discussion

48.	The increase of efficiency of a compression ignition engine, as the load decreases, is due to
A.	higher maximum temperature
B.	qualitative governing
C.	quantitative governing
D.	hit and miss governing
Answer» C. quantitative governing

Discussion

49.	In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then __________ is employed.
A.	fuel pump
B.	injector
C.	carburettor
D.	none of these
Answer» D. none of these

Discussion

50.	The colour of exhaust from diesel engine is generally
A.	white
B.	bluish
C.	black
D.	violent
Answer» D. violent

Discussion

Explore topic-wise MCQs in Testing Subject.

A nuclear power plant differs from a conventional steam power station only in the steam generating part.

In a four stroke engine, the working cycle is completed in

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

The efficiency of roots blower __________ with the increase in pressure ratio.

The operation of lifts, rams and pumps make use of compressed air.

In a compressed air system, the temperature of air discharged from the air motor is __________ than the initial compressor intake temperature.

Which of the following statement is correct relating to rocket engines ?

In reciprocating air compressors, isothermal efficiency is used for all sorts of calculations.

Euler's equation can be used for

A jet engine has

A rocket engine uses __________ for the combustion of its fuel.

Free air is the air at atmospheric conditions at any specific location.

The perfect intercooling, in multistage compression, means that the temperature of air at inlet to subsequent stages is equal to the initial temperature.

A gas turbine used in air-craft should have low weight and small frontal area.

A closed cycle gas turbine works on

Air motors work on the cycle which is the reverse of the reciprocating air compressor cycle.

The axial flow compressor is preferred in air-craft gas turbines because of

Which of the following statement is correct as regard to centrifugal compressors?

The ratio of the net work obtained from the gas turbine plant to the turbine work is known as

The clearance, in a single stage, single acting reciprocating air compressor does not effect the workdone on the air and the power required for compressing the air.

The process, which causes the air to enter the impeller blades of a centrifugal compressor at __________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

A closed cycle gas turbine consists of a

A receiver in compressor installations is used to damp pressure waves in compressor discharge.

In jet propulsion power unit, the inlet duct of diverging shape is used for converting kinetic energy of air into pressure energy.

For maximum work, the reheating should be done to an intermediate pressure of (where p1 = Maximum pressure, and p2 = Minimum pressure)

The temperature of air at the beginning of the compression stroke is __________ the atmospheric temperature.

The pressure ratio in a centrifugal compressor can be increased by increasing the tip speed and lowering the inlet temperature.

Gas turbine as compared to internal combustion engine

A two stroke cycle engine occupies larger floor area than a four stroke cycle engine.

The compressor efficiency is defined as the ratio of volume of free air delivery per stroke to the swept volume of the piston.

In a four stroke cycle petrol engine, , the compression

In a gas turbine, air is obtained from the atmosphere and compressed in an air compressor.

The overall efficiency is defined as the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.

The reflectivity of a reflector is defined as the fraction of neutrons entering the reflector which are returned to the core.

Reflector in nuclear power plants is used to reflect neutrons back into the active core.

The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of

The turbine of the turbo-prop engine is __________ that of the turbo-jet engine.

The pressure at the end of compression, in petrol engines, is approximately

The sparking in a petrol engine increases pressure and temperature of the products of combustion, but the volume remains constant.

A higher compression ratio causes

A diesel engine is __________ as compared to petrol engine, both running at rated load.

In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.

The combustion in compression ignition engines is

Which of the following fuel detonates readily ?

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

The cetane (C16H34) which is a straight chain paraffin is assigned a cetane number of

Morse test is used to determine the I.P. of a

The increase of efficiency of a compression ignition engine, as the load decreases, is due to

In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then __________ is employed.

The colour of exhaust from diesel engine is generally