260+ Internal Combustion Engines (I.C. Engines) Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .

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1.	Advantage of reciprocating IC engines over steam turbine is
A.	Mechanical simplicity
B.	Improved plant efficiency
C.	Lower average temperature
D.	all of the above
Answer» D. all of the above

discuss

2.	The intake charge in a diesel engine consists of
A.	air alone
B.	air + lubricating oil
C.	air + fuel
D.	air + fuel + lubricating oil
Answer» A. air alone

discuss

3.	Engines of different cylinder dimensions, power and speed can be compared on the basis of
A.	Maximum pressure
B.	Fuel consumption
C.	mean effective pressure
D.	unit power
Answer» C. mean effective pressure

discuss

4.	Disadvantages of reciprocating IC engine are
A.	vibration
B.	use of fossil fuels
C.	balancing problems
D.	all of the above
Answer» D. all of the above

discuss

5.	Gudgeon pin forms the link between
A.	piston and big end of connecting rod
B.	piston and small end of connecting rod
C.	connecting rod and crank
D.	big end and small end
Answer» B. piston and small end of connecting rod

discuss

6.	In a four-stroke IC engine cam shaft rotates at
A.	same speed as crankshaft
B.	twice the speed of crankshaft
C.	halt the speed of crankshaft
D.	none of the above
Answer» C. halt the speed of crankshaft

discuss

7.	Thermal efficiency of CI engine is higher than that of SI engine due
A.	light weight
B.	higher compression ratio
C.	constant pressure heat addition
D.	none of the above
Answer» B. higher compression ratio

discuss

8.	SI engines are of
A.	light weight
B.	high speed
C.	homogeneous change of fuel and oil
D.	all of the above
Answer» D. all of the above

discuss

9.	Compression ratio in diesel engines is of the order of
A.	5-7
B.	7 -10
C.	10 – 12
D.	14-20
Answer» D. 14-20

discuss

10.	Main advantage of a two-stroke engine over four-stroke engine is
A.	more uniform torque on the crankshaft
B.	more power output for the cylinder of same dimensions
C.	absence of valves
D.	all of the above
Answer» D. all of the above

discuss

11.	Engines used for ships are normally
A.	four-stroke Sl engines of very high power
B.	two-stroke CI engines of very high power
C.	four-stroke Cl engines of high speed
D.	two-stroke SI engines of high power
Answer» B. two-stroke CI engines of very high power

discuss

12.	If L is the stroke and N is the rpm, mean piston speed of two-stroke engine
A.	LN
B.	LN/2
C.	2LN
D.	none of the above
Answer» C. 2LN

discuss

13.	The volumetric efficiency of the SI engine is comparatively
A.	lower than CI engine
B.	higher than CI engine
C.	will be same as CI engine
D.	none of the above
Answer» A. lower than CI engine

discuss

14.	Brake specific fuel consumption is defined as
A.	fuel consumption per hour
B.	fuel consumption per km
C.	fuel consumption per BP
D.	fuel consumption per brake power hour
Answer» D. fuel consumption per brake power hour

discuss

15.	Engine can be fired with
A.	solid fuel
B.	liquid fuel
C.	gaseous fuel
D.	any of the above fuels
Answer» D. any of the above fuels

discuss

16.	A two-stroke engine can be identified by
A.	cooling system
B.	lubrication system
C.	absence of valves
D.	piston size
Answer» C. absence of valves

discuss

17.	Advantage of two-stroke engine is
A.	more uniform torque
B.	lighter flywheel
C.	no valves
D.	all of the above
Answer» D. all of the above

discuss

18.	Charge pressure at the inlet port of a two-stroke engine is
A.	20 bar
B.	vacuum
C.	atmospheric
D.	higher than atmospheric
Answer» D. higher than atmospheric

discuss

19.	The most perfect method of scavenging is
A.	cross scavenging
B.	uniflow scavenging
C.	loop scavenging
D.	reverse flow scavenging
Answer» B. uniflow scavenging

discuss

20.	Two-stroke SI engines suffer from
A.	fuel loss
B.	idling difficulty
C.	both (a) and (b) together
D.	none of the above
Answer» A. fuel loss

discuss

21.	At the same speed two-stroke engine of the same size as a four-stroke engine will develop
A.	same power
B.	half the power
C.	twice the power
D.	four times the power
Answer» C. twice the power

discuss

22.	Two wheelers without deflector type piston use
A.	loop scavenging
B.	unifow scavenging
C.	reverse flow scavenging
D.	cross scavenging
Answer» D. cross scavenging

discuss

23.	Crankcase scavenged engines have delivery ratio of
A.	greater than 1
B.	less than 1
C.	equal to 1
D.	none of the above
Answer» C. equal to 1

discuss

24.	The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft
A.	1/2
B.	1
C.	2
D.	4
Answer» C. 2

discuss

25.	In a diesel engine, the fuel is ignited by
A.	spark
B.	injected fuel
C.	heat resulting from compressing air that is supplied for combustion
D.	ignitor
Answer» C. heat resulting from compressing air that is supplied for combustion

discuss

26.	Scavenging air in diesel engine means
A.	air used for combustion sent under pres-sure
B.	forced air for cooling cylinder
C.	burnt air containing products of com-bastion
D.	air used for forcing burnt gases out of engine's cylinder during the exhaust period
Answer» D. air used for forcing burnt gases out of engine's cylinder during the exhaust period

discuss

27.	Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?
A.	yes
B.	no
C.	to some extent
D.	unpredictable
Answer» B. no

discuss

28.	The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
A.	net efficiency
B.	efficiency ratio
C.	relative efficiency
D.	overall efficiency
Answer» C. relative efficiency

discuss

29.	Compression ratio of LC. Engines is
A.	the ratio of volumes of air in cylinder before compression stroke and after compression stroke
B.	volume displaced by piston per stroke and clearance volume in cylinder
C.	ratio of pressure after compression and before compression
D.	swept volume/cylinder volume
Answer» A. the ratio of volumes of air in cylinder before compression stroke and after compression stroke

discuss

30.	A perfect engine works on the Carnot cycle between 727 °C and 227°C. The efficiency of the engine is
A.	0.5
B.	0.75
C.	1
D.	0.25
Answer» A. 0.5

discuss

31.	The air standard Otto cycle consists of
A.	two constant volume and two isentropic processes
B.	two constant pressure and two isentropic processes
C.	two constant pressure and two constant volume processes
D.	none of the above
Answer» A. two constant volume and two isentropic processes

discuss

32.	In air standard Diesel cycle at fixed r and fixed n
A.	ƞthermal increases with increase in heat addition and cut-off ratio
B.	ƞthermal decreases with increase in heat addition and cut-off ratio
C.	ƞthermal Remains the same with increase in heat addition and cut-off ratio
D.	none of the above
Answer» B. ƞthermal decreases with increase in heat addition and cut-off ratio

discuss

33.	Mean effective pressure of Otto cycle is
A.	inversely proportional to pressure ratio
B.	directly proportional to pressure ratio
C.	does not depend on pressure ratio
D.	proportional to square root of pressure ratio
Answer» B. directly proportional to pressure ratio

discuss

34.	For a given compression ratio the work output of Otto cycle is
A.	increases with Increase in r
B.	decreases with increase in r
C.	is not affected
D.	none of the above
Answer» A. increases with Increase in r

discuss

35.	For a given value of r, efficiency of Otto cycle
A.	decreases with compression ratio
B.	increases with compression ratio
C.	is not affected
D.	none of the above
Answer» B. increases with compression ratio

discuss

36.	For dual combustion cycle for fixed value of heat addition and compression ratio
A.	mep wil be greater with increase in rp, and decrease in rc
B.	mep will be greater with decrease in rp and decrease in rc
C.	mep remain the same with increase in rp and decrease in rc
D.	none of the above
Answer» A. mep wil be greater with increase in rp, and decrease in rc

discuss

37.	The normal range of, compression ratio for Otto cycle is
A.	6 to 10
B.	2 to 4
C.	>10
D.	none of the above
Answer» A. 6 to 10

discuss

38.	The normal range of compression ratio for Diesel cycle is
A.	4 to 6
B.	6 to 8
C.	15 to 20
D.	>25
Answer» C. 15 to 20

discuss

39.	For the same compression ratio and heat addition
A.	ƞOtto > ƞDiesel > ƞDual
B.	ƞDiesel > ƞOtto > ƞDual
C.	ƞOtto> ƞDual > ƞDiesel
D.	ƞDual> ƞDiesel > ƞOtto
Answer» C. ƞOtto> ƞDual > ƞDiesel

discuss

40.	for the same compression ratio and heat rejection,
A.	ƞOtto> ƞDual > ƞDiesel
B.	ƞDiesel > ƞDual > ƞOtto
C.	ƞDual> ƞDiesel > ƞOtto
D.	ƞDual> ƞOtto> ƞDiesel
Answer» A. ƞOtto> ƞDual > ƞDiesel

discuss

41.	When the engines are built to withstand the sane thermal and mechanical stresses
A.	ƞDiesel > ƞDual > ƞOtto
B.	ƞDual> ƞDiesel > ƞOtto
C.	ƞOtto> ƞDual > ƞDiesel
D.	ƞOtto> ƞDiesel > ƞDual
Answer» A. ƞDiesel > ƞDual > ƞOtto

discuss

42.	For the same peak pressure and heat input
A.	ƞOtto > ƞDual > ƞDiesel
B.	ƞOtto > ƞDiesel > ƞDual
C.	ƞDiesel > ƞDual > ƞOtto
D.	ƞDiesel > ƞOtto > ƞDual
Answer» C. ƞDiesel > ƞDual > ƞOtto

discuss

43.	For the same peak pressure and work output
A.	ƞOtto > ƞDual > ƞDiesel
B.	ƞOtto > ƞDiesel > ƞDual
C.	ƞDiesel > ƞOtto > ƞDual
D.	ƞDiesel > ƞDual > ƞOtto
Answer» D. ƞDiesel > ƞDual > ƞOtto

discuss

44.	Brayton cycle is used in
A.	Ramjet engines
B.	gas turbines
C.	pulse jet engines
D.	Cl engines
Answer» B. gas turbines

discuss

45.	The actual efficiency of a good engine is about _______of the estimated fuel-air cycle efficiency.
A.	100%
B.	85%
C.	50%
D.	25%
Answer» B. 85%

discuss

46.	With dissociation peak temperature is obtained
A.	at the stoichiometric air-fuel ratio
B.	when the mixture is slightly lean
C.	when the mixture is slightly rich
D.	none of the above
Answer» C. when the mixture is slightly rich

discuss

47.	With dissociation the exhaust gas temperature
A.	decreases
B.	increases
C.	no effect
D.	increases upto certain air-fuel ratio and then decreases
Answer» A. decreases

discuss

48.	Fuel-air ratio affects maximum power output of the engine due to
A.	higher specific heats
B.	chemical equilibrium losses
C.	both (a) and (b)
D.	none of the above
Answer» C. both (a) and (b)

discuss

49.	Mean effective pressure at a given compression ratio is maximum when the air-fuel ratio is
A.	higher than stoichiometric
B.	lower than stoichiometric
C.	equal to stoichionetric
D.	none of the above
Answer» B. lower than stoichiometric

discuss

50.	For a compressor process with variable specific heat the peak temperature and pressure are _______compared to constant specific heat
A.	lower
B.	higher
C.	no effect
D.	none of the above
Answer» A. lower

discuss

260+ Internal Combustion Engines (I.C. Engines) Solved MCQs

Advantage of reciprocating IC engines over steam turbine is

The intake charge in a diesel engine consists of

Engines of different cylinder dimensions, power and speed can be compared on the basis of

Disadvantages of reciprocating IC engine are

Gudgeon pin forms the link between

In a four-stroke IC engine cam shaft rotates at

Thermal efficiency of CI engine is higher than that of SI engine due

SI engines are of

Compression ratio in diesel engines is of the order of

Main advantage of a two-stroke engine over four-stroke engine is

Engines used for ships are normally

If L is the stroke and N is the rpm, mean piston speed of two-stroke engine

The volumetric efficiency of the SI engine is comparatively

Brake specific fuel consumption is defined as

Engine can be fired with

A two-stroke engine can be identified by

Advantage of two-stroke engine is

Charge pressure at the inlet port of a two-stroke engine is

The most perfect method of scavenging is

Two-stroke SI engines suffer from

At the same speed two-stroke engine of the same size as a four-stroke engine will develop

Two wheelers without deflector type piston use

Crankcase scavenged engines have delivery ratio of

The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

In a diesel engine, the fuel is ignited by

Scavenging air in diesel engine means

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

The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called

Compression ratio of LC. Engines is

A perfect engine works on the Carnot cycle between 727 °C and 227°C. The efficiency of the engine is

The air standard Otto cycle consists of

In air standard Diesel cycle at fixed r and fixed n

Mean effective pressure of Otto cycle is

For a given compression ratio the work output of Otto cycle is

For a given value of r, efficiency of Otto cycle

For dual combustion cycle for fixed value of heat addition and compression ratio

The normal range of, compression ratio for Otto cycle is

The normal range of compression ratio for Diesel cycle is

For the same compression ratio and heat addition

for the same compression ratio and heat rejection,

When the engines are built to withstand the sane thermal and mechanical stresses

For the same peak pressure and heat input

For the same peak pressure and work output

Brayton cycle is used in

The actual efficiency of a good engine is about _______of the estimated fuel-air cycle efficiency.

With dissociation peak temperature is obtained

With dissociation the exhaust gas temperature

Fuel-air ratio affects maximum power output of the engine due to

Mean effective pressure at a given compression ratio is maximum when the air-fuel ratio is

For a compressor process with variable specific heat the peak temperature and pressure are _______compared to constant specific heat