Explore topic-wise MCQs in Heat Engines.

This section includes 460 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Engines knowledge and support exam preparation. Choose a topic below to get started.

1.

Which of the boiler provides superheated steam?

A. Locomotive boiler
B. Lancashire boiler
C. Cornish boiler
D. All of the above
E. None of the above
Answer» B. Lancashire boiler
Discussion
2.

After cooler is used to

A. Cool the air
B. Reduce the volume of air
C. To cause moisture and oil vapour to drop out
D. Remove impurities from air
E. None of the above
Answer» B. Reduce the volume of air
Discussion
3.

Thermal efficiency of C.I. engines on weak mixtures is

A. Higher
B. Lower
C. Unaffected
D. Depends on other factors
E. None of the above
Answer» B. Lower
Discussion
4.

Brayton cycle cannot be used in reciprocating engines even for same compression rations and work output because

A. Large volume at low pressure cannot be efficiently harded in reciprocating engines
B. Brayton cycle is less efficient
C. Otto cycle is more efficient
D. Brayton cycle requires large air-fuel ratio
E. Brayton cycle is for slow speed engines only
Answer» B. Brayton cycle is less efficient
Discussion
5.

The governor for steam turbine is driven by

A. Main shaft
B. Separate motor
C. Belt drive
D. Feed pump motor
E. None of the above
Answer» B. Separate motor
Discussion
6.

Working in the cryogenic range means dealing with temperatures

A. Below absolute zero
B. Below zero degree centigrade
C. Between - 190?C and absolute zero
D. Prevailing normally in the atomsphere
E. Between zero degree centigrade and 190?C
Answer» D. Prevailing normally in the atomsphere
Discussion
7.

A barN is

A. A unit of area
B. A unit of length
C. A unit of time
D. A unit of mass
E. None of the above
Answer» B. A unit of length
Discussion
8.

A compound pressure gauge measures

A. Average pressure
B. Positive and negative pressures
C. Compound pressures
D. Variable pressures
E. Complex pressures
Answer» C. Compound pressures
Discussion
9.

If a engine working on Otto cycle has its compression ratio raised from 5 to 6 the percentage increase in air standard efficiency will be

A. 4%
B. 10%
C. 6%
D. 8%
E. 1%
Answer» B. 10%
Discussion
10.

A sample having pH value of 5 will be

A. Neutral
B. Acidic
C. Alkalino
D. None of the above
Answer» C. Alkalino
Discussion
11.

For combustion of one kg of carbon the quantity of oxygen required (air contains 23% by wight of oxygen) is

A. 12 kg
B. 8 kg
C. 2.62 kg
D. 11.6 kg
E. 3.67 kg
Answer» D. 11.6 kg
Discussion
12.

Air preheater in a boiler will be invariably located between

A. Condenser and feed water pump
B. Water treatment plant and furnace
C. Boiler furnace and chimney
D. Economiser and feed pump
E. Forced draft fan and furnace
Answer» F.
Discussion
13.

A negative loop in the P-V diagram of a petrol engine is due to

A. Carbon dioxide
B. Suction of air
C. pre-ignition
D. early opening of exnaust valve
E. detonation
Answer» E. detonation
Discussion
14.

Dew point temperature is an indication of

A. Condition of air
B. Condition of moisture in air
C. Dryness of air
D. Lowest temperature where air and water vapour start separating
E. Moisture constant of air
Answer» E. Moisture constant of air
Discussion
15.

If a steam injector fails to lift the water the trouble may not be due to

A. Too low steam pressure for list
B. Water pipe clogged
C. Water supply to cold
D. End of water pipe not submerged
E. None of the above
Answer» D. End of water pipe not submerged
Discussion
16.

The mean effective pressure of a diesel cycle having fixed compression ratio will increase if cut off ratio will

A. Increase
B. Decrease
C. Independent of CR
D. Depends on other factors
E. None of the above
Answer» B. Decrease
Discussion
17.

In Parsons reaction turbine

A. The fixed and moving blades are identical
B. The velocity biagram is unsymmetrical about a vertical centre line
C. The degree of reaction is
D. The fixed blades are smaller in size as compared to moving blades
E. The fixed blades are larger in size compared to fixed blades
Answer» B. The velocity biagram is unsymmetrical about a vertical centre line
Discussion
18.

In isothermal compression

A. There is no gain internal energy
B. Temperature increses very slowly
C. There is no exchange of heat with environment
D. Entropy changes is zero
E. None of the above
Answer» B. Temperature increses very slowly
Discussion
19.

A system having connected load of 100 kW, peak load of 80 kW, base load of 20 kW and average load of 40 kW will have a load factor of

A. 60%
B. 40%
C. 75%
D. 80%
E. 50%
Answer» F.
Discussion
20.

A run-of-river hydro-electric station is one which is

A. Located on a small river
B. Located on a river which does not flow throughout the year
C. Located on a steam flow without water storage
D. Locted on a steam flow with large water storage
E. None of the above
Answer» D. Locted on a steam flow with large water storage
Discussion
21.

Starting motor in automobiles is generally

A. Induction motor
B. Synchronous motor
C. Squirrel cage motor
D. Shunt motor
E. Series motor
Answer» F.
Discussion
22.

Tenacity is the property of materials in which they

A. Resist indentation
B. Resist rupture
C. Resist shearing
D. Resist deformation
E. None of the above
Answer» C. Resist shearing
Discussion
23.

Air standard efficiency of an I.C. engine depends on

A. Compression ratio
B. Speed of operation
C. Fuel used
D. Torque
E. All of the above
Answer» B. Speed of operation
Discussion
24.

Air consumption of a four-stroke diesel engine per rated BHP/hr will be

A. 20 kg
B. 1 kg
C. 5 - 7 kg
D. 10 - 14 kg
E. 15 kg
Answer» D. 10 - 14 kg
Discussion
25.

If the power factor of an electrical system is unity, it means

A. Efficiency is least
B. Entire power is consumed in reactive power
C. Entire power pulls the load
D. Equipment is running properly
E. Magnetism generated within the equipment is negligible
Answer» D. Equipment is running properly
Discussion
26.

As the steam flows in a subsonic nozzle, in which the cross-section is decreasing in the direction of flow

A. The velocity will decrease in the direction of flow
B. The pressure will increase in the direction of flow
C. The velocity will decrease while pressure will decrease in the direction of flow
D. The velocity will increase while pressure will decrease in the direction of flow
E. None of the above
Answer» E. None of the above
Discussion
27.

A fixed quantity of heat is to be added to a system under specific conditions. The process in which the entropy change will be maximum is

A. Constant pressure process
B. Constant volume process
C. Constant temperature process
D. Isentropic process
E. None of the above
Answer» D. Isentropic process
Discussion
28.

Out of the following diesel engine the minimum air consumption per B.H.P. will be in

A. 50%
B. 4 stroke, air injection
C. 2 stroke, air injection
D. 2 stroke, mech, injection, pump, scavenging
E. 4 stroke, mech, injection
Answer» F.
Discussion
29.

Willian's line is relevant to

A. Throttle controlled trbine
B. Nozzle controlled turbines
C. Impulse turbines
D. Reaction turbines
E. None of the above
Answer» B. Nozzle controlled turbines
Discussion
30.

White smoke from a diesel engine can be expected during

A. Start up or idling
B. High speed operation
C. High load operation
D. All of the above
E. None of the above
Answer» B. High speed operation
Discussion
31.

Three states of matter are distinguished with repect to molecules by

A. Characteristics of the motion of molecules
B. The number
C. Energy of molecules
D. The atoms in molecules
E. The orientation of molecules
Answer» B. The number
Discussion
32.

Rankine cycle efficiency for fixed steam temperature of any volume upto critical temperature will be maximum for steam pressure of

A. 250 kg/cm2
B. 100 kg/cm2
C. 200 kg/cm2
D. Critical pressure
E. 203.5 kg/cm2
Answer» E. 203.5 kg/cm2
Discussion
33.

The horse power of engine for a ship is of the order to

A. 10,000 to 40,000
B. 50 to 100
C. 1000 to 5000
D. 100 to 500
E. 500 to 1000
Answer» B. 50 to 100
Discussion
34.

Endurance test for I.C. engines is conducted for

A. 1000 hours
B. 200 hours
C. 500 hours
D. 400 hours
E. 100 hours
Answer» D. 400 hours
Discussion
35.

A certain gas occupies 2 cu-m at a temperature of 400?C. It receives heat at constant pressure till its temperature is doubled. The change in volume would be

A. 0.19 cu-m
B. 3.8 cu-m
C. 0.038 cu-m
D. 0.019 cu-m
E. 3.188 cu-m
Answer» F.
Discussion
36.

Prony brakes are used for testing

A. Slow speed engines
B. High speed engines
C. Engines with small flywheel
D. Small engines
E. Large capacity engines
Answer» E. Large capacity engines
Discussion
37.

A Wankel engine combines the advantages of

A. SI and CI engines
B. Carburction and fuel injection
C. Air cooled and reciprocating engines
D. Rotory and reciprocating engines
E. Axial flow and centrifugal compression
Answer» E. Axial flow and centrifugal compression
Discussion
38.

Change in internal energy is least during

A. 25 to 30
B. Constant pressure process
C. Constant volume process
D. Adiabatic process
E. Isothermal process
Answer» F.
Discussion
39.

The pour point of diesel fuel oil must be

A. More than the coldest atmospheric temperature at which oil is to be pumped
B. Less than 0?C
C. Less than the coldest atmospheric temperature of which oil is to be pumped
D. More than 100?C
E. More than 0?C
Answer» D. More than 100?C
Discussion
40.

In wet dry lubrication of diesel engines

A. Oil is splashed
B. Oil is splashed and pumped to various points
C. Oil is pumped to various points
D. All of the above
E. None of the above
Answer» D. All of the above
Discussion
41.

Highest useful compression ratio is the compression ratio at which

A. An engine can be safely operated
B. An engine gives maximum thermal efficiency
C. An engine operates smoothly
D. Detonation first becomes audible
E. None of the above
Answer» E. None of the above
Discussion
42.

A steam nozzle is said to be choked when

A. Pressure at throat is equal to steam supply pressure
B. Throat gets clogged
C. Flow is at maximum value of critical exit pressure
D. Steam flow through nozzle ceases
E. Pressure at throat is less than the exit pressure
Answer» F.
Discussion
43.

The fact that the product of pressure and volume of a fixed amount of gas is approximately a constant value is known as

A. Charle's law
B. Gay Lusac's law
C. Dalton's law
D. Lewis law
E. None of the above
Answer» F.
Discussion
44.

In a four stroke cycle the minimum temperature inside the engine cylinder occurs

A. At the end of exhaust stroke
B. At the end of suction stroke
C. At the end of compression stroke
D. At the beginning of exhaust stroke
E. At the beginning of suction stroke
Answer» C. At the end of compression stroke
Discussion
45.

According to Charle's law

A. At constant pressure the volume of a gas is proportional to its absolute temperature
B. At constant temperature, pressure is proportional to temperature
C. At constant temperature, pressure of a gas is proportional to its volume
D. At constant volume the absolute pressure is proportional to the temperature
E. None of the above
Answer» B. At constant temperature, pressure is proportional to temperature
Discussion
46.

A Lungistrom turbine is a

A. Radial flow reaction turbine
B. Axial flow reaction turbine
C. Radial flow impulse turbine
D. Mixed flow impulse turbine
E. None of the above
Answer» B. Axial flow reaction turbine
Discussion
47.

Thermal efficiency of a standard Otto cycle for a compression ratio 5.5, will be

A. 100%
B. 47.50%
C. 20%
D. 35.40%
E. 50%
Answer» F.
Discussion
48.

Solid injection in diesel engines implies

A. Use of solid fuels
B. Supply of fuel in the form of solid
C. Injecting fuel with lubricating oil
D. Injecting fuel and air simultaneously
E. Injecting fuel without air
Answer» F.
Discussion
49.

The calorific value of methane can be determined by

A. Bomb calorimeter
B. Bunsen's calorimeter
C. Orsat's apparatus
D. Exhaust gas calorimeter
E. None of the above
Answer» F.
Discussion
50.

The molecular weight of a mixture containing 20% oxygen, 20 percent nitrogen and 60 percent carbon dioxise on volume bases will be nearly

A. 38.4
B. Carbon dioxide
C. 41.4
D. 29.9
E. 33.3
Answer» B. Carbon dioxide
Discussion