4791 + Mcqs in Mechanical Engineering Page 90 McqOptions

4451.	Which of the following statement is correct regarding petrol engines?
A.	A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure.
B.	The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug.
C.	The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition.
D.	all of the above
Answer» C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition.

Discussion

4452.	The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
A.	pressure drop across the valves
B.	superheating in compressor
C.	clearance volume and leakages
D.	all of these
Answer» E.

Discussion

4453.	In order to eliminate knocking in compression ignition engines, there should be
A.	short delay period
B.	late auto-ignition
C.	low compression ratio
D.	high self ignition temperature of fuel
Answer» B. late auto-ignition

Discussion

4454.	The higher combustion chamber wall temperature in compression ignition engines will __________ knocking tendency.
A.	increase
B.	reduce
C.	not effect
Answer» C. not effect

Discussion

4455.	The nuclear radiators produced in a reactor which must be sheilded are
A.	electrons
B.	, and rays
C.	neutron and gamma rays
D.	none of these
Answer» D. none of these

Discussion

4456.	Rateau turbine is
A.	simple reaction turbine
B.	velocity compounded turbine
C.	pressure compounded turbine
D.	pressure-velocity compounded turbine
Answer» D. pressure-velocity compounded turbine

Discussion

4457.	The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine.
A.	True
B.	False
Answer» B. False

Discussion

4458.	Curtis turbine is a
A.	simple reaction turbine
B.	velocity compounded turbine
C.	pressure compounded turbine
D.	pressure-velocity compounded turbine
Answer» E.

Discussion

4459.	The velocity of steam at throat of the nozzle is __________ the velocity of sound.
A.	equal to
B.	less than
C.	more than
Answer» B. less than

Discussion

4460.	The ratio of the isentropic heat drop to the heat supplied, is called
A.	reheat factor
B.	stage efficiency
C.	internal efficiency
D.	Rankine efficiency
Answer» E.

Discussion

4461.	In an impulse turbine
A.	the steam is expanded in nozzles only and there is a pressure drop and heat drop
B.	the steam is expanded both in fixed and moving blades continuously
C.	the steam is expanded in moving blades only
D.	the pressure and temperature of steam remains constant
Answer» B. the steam is expanded both in fixed and moving blades continuously

Discussion

4462.	In a reaction turbine
A.	the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
B.	the expansion of steam takes place partly in the fixed blades and partly in the moving blades
C.	the steam is expanded from a high pressure to a condenser pressure in one or more nozzles
D.	the pressure and temperature of steam remains constant
Answer» C. the steam is expanded from a high pressure to a condenser pressure in one or more nozzles

Discussion

4463.	A steam nozzle converts
A.	heat energy of steam into kinetic energy
B.	kinetic energy into heat energy of steam
C.	heat energy of steam into potential energy
D.	potential energy into heat energy of steam
Answer» B. kinetic energy into heat energy of steam

Discussion

4464.	Steam turbines may be classified according to
A.	direction of steam flow
B.	number of stages
C.	mode of steam action
D.	all of these
Answer» E.

Discussion

4465.	When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.
A.	increases
B.	decreases
Answer» C.

Discussion

4466.	In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is
A.	low
B.	very low
C.	high
D.	very high
Answer» E.

Discussion

4467.	The increase in pressure in a roots blower is entirely due to back flow of air.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4468.	In open cycle turbo-jet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the
A.	thrust and range of aircraft
B.	efficiency of the engine
C.	both (a) and (b)
D.	none of these
Answer» B. efficiency of the engine

Discussion

4469.	A nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.
A.	True
B.	False
Answer» B. False

Discussion

4470.	Workdone by a two-stage reciprocating air compressor per cycle is equal to the workdone in LP. cylinder and H.P. cylinder.
A.	True
B.	False
Answer» B. False

Discussion

4471.	When the temperature of air leaving the intercooler, in a two stage compression with intercooler, is __________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.
A.	equal to
B.	less than
C.	more than
Answer» B. less than

Discussion

4472.	Only rocket engines can be propelled to space because
A.	they can generate very high thrust
B.	they have high propulsion efficiency
C.	these engines can work on several fuels
D.	they are not air-breathing engines
Answer» E.

Discussion

4473.	The type of rotary compressor used in aeroplanes, is of
A.	centrifugal type
B.	axial flow type
C.	radial flow type
D.	none of these
Answer» C. radial flow type

Discussion

4474.	The pressure of air at the beginning of the compression stroke is __________ the atmospheric pressure.
A.	equal to
B.	less than
C.	more than
Answer» C. more than

Discussion

4475.	The ratio of the isentropic work to the Euler's work is known as pressure coefficient.
A.	Yes
B.	No
Answer» B. No

Discussion

4476.	If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by
A.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/373-82-1.png">
B.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/373-82-2.png">
C.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/373-82-3.png">
D.	<img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/373-82-4.png">
Answer» C. <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/373-82-3.png">

Discussion

4477.	The degree of reaction is usually kept __________ for all types of axial flow compressors.
A.	0.2
B.	0.3
C.	0.4
D.	0.5
Answer» E.

Discussion

4478.	The basic principle of the rocket propulsion is the same as that of jet propulsion.
A.	Yes
B.	No
Answer» B. No

Discussion

4479.	In a single stage, single acting reciprocating air compressor without clearance volume, the workdone is maximum during
A.	isothermal compression
B.	isentropic compression
C.	polytropic compression
D.	none of these
Answer» C. polytropic compression

Discussion

4480.	In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during
A.	isothermal compression
B.	isentropic compression
C.	polytropic compression
D.	none of these
Answer» B. isentropic compression

Discussion

4481.	A centrifugal compressor is an axial flow compressor.
A.	Correct
B.	Incorrect
Answer» C.

Discussion

4482.	A compressor mostly used for supercharging of I.C. engines is
A.	radial flow compressor
B.	axial flow compressor
C.	roots blower
D.	reciprocating compressor
Answer» B. axial flow compressor

Discussion

4483.	The volume of air sucked by the compressor during its suction stroke is called
A.	free air delivery
B.	compressor capacity
C.	swept volume
D.	none of these
Answer» D. none of these

Discussion

4484.	A diesel engine has
A.	one valve
B.	two valves
C.	three valves
D.	four valves
Answer» D. four valves

Discussion

4485.	The detonation is also called knocking or pinking.
A.	Yes
B.	No
Answer» B. No

Discussion

4486.	The pre-ignition occurs before the spark is produced whereas detonation develops after the introduction of spark.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4487.	If V1 is the jet velocity and V0 is the vehicle velocity, then propulsive efficiency of a turbo-jet engine is
A.	<img src="/_files/images/mechanical-engineering/ic-engines-and-nuclear-power-plants/350-192-1.png">
B.	<img src="/_files/images/mechanical-engineering/ic-engines-and-nuclear-power-plants/350-192-2.png">
C.	<img src="/_files/images/mechanical-engineering/ic-engines-and-nuclear-power-plants/350-192-3.png">
D.	<img src="/_files/images/mechanical-engineering/ic-engines-and-nuclear-power-plants/350-192-4.png">
Answer» D. <img src="/_files/images/mechanical-engineering/ic-engines-and-nuclear-power-plants/350-192-4.png">

Discussion

4488.	In qualitative governing, the quantity of fuel is varied to suit the load on the engine and the total charge of air is altered.
A.	Correct
B.	Incorrect
Answer» C.

Discussion

4489.	A supercharged engine as compared to an ordinary engine
A.	requires smaller foundation
B.	is lighter
C.	consumes less lubricating oil
D.	all of these
Answer» E.

Discussion

4490.	Supercharging __________ the power developed by the engine.
A.	has no effect on
B.	increases
C.	decreases
Answer» C. decreases

Discussion

4491.	A turbo-jet does not require a turbine to drive the compressor.
A.	True
B.	False
Answer» C.

Discussion

4492.	The working pressure and temperature inside the cylinder of an internal combustion engine is __________ as compared to a steam engine.
A.	low
B.	very low
C.	high
D.	very high
Answer» E.

Discussion

4493.	Number of working strokes per min. for a four stroke cycle engine are __________ the speed of the engine in r.p.m.
A.	equal to
B.	one-half
C.	twice
D.	four-times
Answer» C. twice

Discussion

4494.	The mean effective pressure of a diesel engine having fixed compression ratio will __________ if cut off ratio decreases.
A.	increase
B.	decrease
Answer» C.

Discussion

4495.	The delay period in oil engines increases with increase in the speed of engine.
A.	Agree
B.	Disagree
Answer» C.

Discussion

4496.	A two stroke cycle engine gives __________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed.
A.	half
B.	same
C.	double
D.	four times
Answer» D. four times

Discussion

4497.	The ignition quality of petrol is expressed by
A.	cetane number
B.	octane number
C.	calorific value
D.	all of these
Answer» C. calorific value

Discussion

4498.	The octane number of petrol, generally available, is
A.	20 to 40
B.	40 to 60
C.	60 to 80
D.	80 to 100
Answer» E.

Discussion

4499.	A diesel engine has inlet valve, fuel injection valve and exhaust valve.
A.	Yes
B.	No
Answer» B. No

Discussion

4500.	The volumetric efficiency ofa well designed engine may be
A.	30 to 40%
B.	40 to 60%
C.	60 to 70%
D.	75 to 90%
Answer» E.

Discussion

Explore topic-wise MCQs in Engineering.

Which of the following statement is correct regarding petrol engines?

The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is

In order to eliminate knocking in compression ignition engines, there should be

The higher combustion chamber wall temperature in compression ignition engines will __________ knocking tendency.

The nuclear radiators produced in a reactor which must be sheilded are

Rateau turbine is

The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine.

Curtis turbine is a

The velocity of steam at throat of the nozzle is __________ the velocity of sound.

The ratio of the isentropic heat drop to the heat supplied, is called

In an impulse turbine

In a reaction turbine

A steam nozzle converts

Steam turbines may be classified according to

When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.

In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is

The increase in pressure in a roots blower is entirely due to back flow of air.

In open cycle turbo-jet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the

A nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.

Workdone by a two-stage reciprocating air compressor per cycle is equal to the workdone in LP. cylinder and H.P. cylinder.

When the temperature of air leaving the intercooler, in a two stage compression with intercooler, is __________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.

Only rocket engines can be propelled to space because

The type of rotary compressor used in aeroplanes, is of

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

The ratio of the isentropic work to the Euler's work is known as pressure coefficient.

If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by

The degree of reaction is usually kept __________ for all types of axial flow compressors.

The basic principle of the rocket propulsion is the same as that of jet propulsion.

In a single stage, single acting reciprocating air compressor without clearance volume, the workdone is maximum during

In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during

A centrifugal compressor is an axial flow compressor.

A compressor mostly used for supercharging of I.C. engines is

The volume of air sucked by the compressor during its suction stroke is called

A diesel engine has

The detonation is also called knocking or pinking.

The pre-ignition occurs before the spark is produced whereas detonation develops after the introduction of spark.

If V1 is the jet velocity and V0 is the vehicle velocity, then propulsive efficiency of a turbo-jet engine is

In qualitative governing, the quantity of fuel is varied to suit the load on the engine and the total charge of air is altered.

A supercharged engine as compared to an ordinary engine

Supercharging __________ the power developed by the engine.

A turbo-jet does not require a turbine to drive the compressor.

The working pressure and temperature inside the cylinder of an internal combustion engine is __________ as compared to a steam engine.

Number of working strokes per min. for a four stroke cycle engine are __________ the speed of the engine in r.p.m.

The mean effective pressure of a diesel engine having fixed compression ratio will __________ if cut off ratio decreases.

The delay period in oil engines increases with increase in the speed of engine.

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

The ignition quality of petrol is expressed by

The octane number of petrol, generally available, is

A diesel engine has inlet valve, fuel injection valve and exhaust valve.

The volumetric efficiency ofa well designed engine may be