Explore topic-wise MCQs in Mechanical Engineering Questions.

This section includes 371 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

51.

The safety valve on boiler drum compared to safety valve on super heater is set at ________________?
A. same value
B. higher value
C. lower value
D. lower/higher depending on steam flow
E. unpredicatble
Answer» C. lower value
Discussion
52.

Which of the following is steam dbal?
A. non-coking bituminous coal
B. brown coal
C. pulverised coal
D. coking bituminous coal
E. none of the above
Answer» B. brown coal
Discussion
53.

The temperature of flue gases at air heater outlet should be__________________?
A. 100°C
B. above dew-point temperature of flue gases
C. below dew-point temperature of flue gases
D. less than wet bulb temperature of flue gases
E. above wet bulb temperature of flue gases
Answer» C. below dew-point temperature of flue gases
Discussion
54.

The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is__________________?
A. less
B. more
C. equal
D. may be less or more depending on temperature
E. unpredictable
Answer» B. more
Discussion
55.

The coal requirement per kW hour generation in the thermal power plant is of the order of__________________?
A. 0.1 to 0.2 kg
B. 0.2 to 0.4 kg
C. 0.6 to 0.8 kg
D. 1.0 to 1.5 kg
E. 1.5 to 2 kg
Answer» D. 1.0 to 1.5 kg
Discussion
56.

At very low temperature, the melting and boiling temperatures become equal. This temperature is____________________?
A. 373°K
B. 273.16°K
C. 303°K
D. 0°K
E. 300°K
Answer» C. 303°K
Discussion
57.

Heating of dry steam above saturation temperature is known as_____________________?
A. enthalpy
B. superheating
C. supersaturation
D. latent heat
E. super tempering
Answer» C. supersaturation
Discussion
58.

Carbonation of coal is the process of________________________?
A. pulverising coal in inert atmosphere
B. heating wood in a limited supply of air at temperatures below 300°C
C. strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. binding the pulverised coal into brick-ettes
E. enriching carbon in the coal
Answer» D. binding the pulverised coal into brick-ettes
Discussion
59.

On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by_______________?
A. horizontal straight line
B. vertical straight line
C. straight inclined line
D. curved line
E. none of the above
Answer» B. vertical straight line
Discussion
60.

If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton’s law, the pressure in condenser is equal to__________________?
A. Ps-Pa
B. pa-ps
C. Pa+P
D. non of these
Answer» D. non of these
Discussion
61.

The specific volume of steam with increase in pressure decreases_____________________?
A. linearly
B. slowly first and then rapidly
C. rapidly first and then slowly
D. inversely
E. none of the above
Answer» D. inversely
Discussion
62.

In a throttling process_________________?
A. heat transfer takes place
B. work is done by the expanding steam
C. internal energy of steam changes
D. all of the above
E. none of the above
Answer» F.
Discussion
63.

The dry saturated steam at very low pressure, (5-10 kg/cm2) when throttled to atmosphere will become________________?
A. wet
B. superheated
C. remain dry satruated
D. dry
E. none of the above
Answer» C. remain dry satruated
Discussion
64.

Superheating of steam is done at_________________?
A. constant volume
B. constant temperature
C. constant pressure
D. constant entropy
E. constant enthaply
Answer» D. constant entropy
Discussion
65.

Heating wet steam at constant temperature is heating it at constant_________________?
A. volume
B. pressure
C. entropy
D. enthalpy
E. none of the above
Answer» C. entropy
Discussion
66.

The dry saturated steam at very high pressure (150-200 kg/cm2) when throttled to atmosphere will become_______________?
A. wet
B. superheated
C. remain dry saturated
D. dry
E. none of the above
Answer» B. superheated
Discussion
67.

Latent heat of dry steam at atmospneric pressure is equal to____________________?
A. 539 kcal/kg
B. 539 BTU/lb
C. 427 kcal/kg
D. 100 kcal/kg
E. 471 kcal/kg
Answer» B. 539 BTU/lb
Discussion
68.

At critical point, i.e. p=225.65 kg/cm2, the latent enthalpy of vaporisation is______________?
A. maximum
B. minimum
C. zero
D. depends on temperature also
E. none of the above
Answer» D. depends on temperature also
Discussion
69.

In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is__________________?
A. 40%
B. 25%
C. 50%
D. 80%
E. 90%
Answer» E. 90%
Discussion
70.

For water, at pressures below atmospheric___________________?
A. melting point rises slightly and boiling point drops markedly
B. melting point rises markedly and boiling point drops markedly
C. melting point drops slightly and boiling point drops markedly
D. melting point drops slightly and boiling point drops slightly
E. none of the above
Answer» B. melting point rises markedly and boiling point drops markedly
Discussion
71.

Sublimation region is the region where__________________?
A. solid and vapour phases are in equi-librium
B. solid and liquid phases are in equilibrium
C. liquid and vapour phases are in equilibrium
D. solid, liquid and vapour phases are in equilibrium
E. none of the above
Answer» B. solid and liquid phases are in equilibrium
Discussion
72.

The critical pressure at which latent heat of vaporisation is zero is________________?
A. 225.65 kgf/cm2
B. 273 kgf/cm2
C. 100 kgf/cm2
D. 1 kgf/cm2
E. – 1 kgf/cm2
Answer» B. 273 kgf/cm2
Discussion
73.

Coke is produced by__________________?
A. pulverising coal in inert atmosphere
B. heating wood in a limited supply of air at temperatures below 300GC
C. strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. binding the pulverised coal into brick-etts
E. enriching carbon in the coal
Answer» D. binding the pulverised coal into brick-etts
Discussion
74.

1 kg.m is equal to_________________?
A. 9.81 Joules
B. All Joules
C. 427 Joules
D. 102 Joules
E. 539 Joules
Answer» B. All Joules
Discussion
75.

A wet vapour can be completely specified by__________________?
A. pressure only
B. temperature only
C. dryness fraction only
D. specific volume only
E. pressure and dryness fraction
Answer» F.
Discussion
76.

One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is__________________?
A. 0.2
B. 0.8
C. 1.0
D. 0.6
E. 0.5
Answer» C. 1.0
Discussion
77.

Equivalent evaporation is the amount of water evaporated in a boiler from and at ____________________?
A. 0°C
B. 100°C
C. saturation temperature at given pressure
D. room temperature
E. 20°C
Answer» C. saturation temperature at given pressure
Discussion
78.

The equivalent evaporation of a boiler is a measure to compare _________________?
A. the given boiler with the model
B. the two different boilers of the same make
C. two different makes of boilers operat¬ing under the same operating conditions
D. two boilers of same make but operaing under different conditions
E. any type of boilers operating under any conditions
Answer» F.
Discussion
79.

Water boils when its vapour pressure ___________________?
A. equals that of the surroundings
B. equals 760 mm of mercury
C. equals to atmospheric pressure
D. equals the pressure of water in the container
E. boiling has ^nothing to do with vapour pressure
Answer» B. equals 760 mm of mercury
Discussion
80.

The specific heat of superheated steam in kcal/kg is generally of the order of___________________?
A. 0.1
B. 0.3
C. 0.5
D. 0.8
E. 1.0
Answer» D. 0.8
Discussion
81.

The state of vapour under saturation condition is described by_______________?
A. pressure alone
B. temperature alone
C. pressure and temperature
D. pressure and dryness fraction
E. dryness fraction alone
Answer» E. dryness fraction alone
Discussion
82.

Stoichiometric quantity of air is the___________________?
A. air present in atmosphere at NTP conditions
B. air required for complete combustion of fuel with no excess air
C. air required for optimum combustion so as to have reasonable excess air
D. air required to convert CO into C02
E. air required to form an explosive mixture
Answer» C. air required for optimum combustion so as to have reasonable excess air
Discussion
83.

The saturation temperature of steam with increase in pressure increases____________________?
A. linearly
B. rapidly first and then slowly
C. slowly first and then rapidly
D. inversely
E. none of the above
Answer» C. slowly first and then rapidly
Discussion
84.

An economiser in a boiler______________________?
A. increases steam pressure
B. increases steam flow
C. decreases fuel consumption
D. decreases steam pressure
E. increases life of boiler
Answer» D. decreases steam pressure
Discussion
85.

Which device is used in thermal power plants to reduce level of pollution___________________?
A. induced draft fan
B. smoke meter
C. chimney
D. precipitator
E. pulveriser
Answer» E. pulveriser
Discussion
86.

Spontaneous combustion is a phenomenon in which____________________?
A. all the fuel burns instantaneously producing high energy release
B. fuel burns with less air
C. coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combi
D. explosion in furnace
E. none of the above
Answer» D. explosion in furnace
Discussion
87.

Ultimate analysis of fuel is determination of percentage of____________________?
A. carbon, hydrogen, nitrogen, sulphur, moisture
B. fixed carbon, ash, volatile matter, moisture
C. higher calorific value
D. lower calorific value
E. best analysis
Answer» B. fixed carbon, ash, volatile matter, moisture
Discussion
88.

The height of chimney in a power plant is governed by__________________?
A. the draft to be created
B. limitation of construction facilities
C. control of pollution
D. quantity of flue gases to be handled
E. all of the above
Answer» D. quantity of flue gases to be handled
Discussion
89.

The maximum discharge through a chimney occurs when the height of chimney is_____________________?
A. infinitely long
B. around 200 meters
C. equal to the height of the hot gas column producing draught
D. outside temperature is very low
E. more than the tallest building nearby
Answer» D. outside temperature is very low
Discussion
90.

Efficiency of a thermal cycle increases by ________________?
A. regeneration
B. reheating of steam
C. both A. and B.
D. cooling of steam
E. none of the above
Answer» D. cooling of steam
Discussion
91.

In forced circulation type boiler__________________?
A. heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
B. water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixtur
C. feed pump is employed to supplement natural circulation in water wall type furnace
D. water is converted into steam in one pass without any recirculation
E. water is heated in a large number of tubes
Answer» E. water is heated in a large number of tubes
Discussion
92.

In locomotives, the draught is produced by_________________?
A. chimney
B. induced draft fan
C. both combined A. and B.
D. steam jet draught
E. none of the above
Answer» E. none of the above
Discussion
93.

Vacuum for reciprocating steam engines compared to steam turbines is__________________?
A. more
B. equal
C. less
D. could be more or less depending on the size of plant
E. none of the above
Answer» D. could be more or less depending on the size of plant
Discussion
94.

In a recuperative air preheater, the heat is transferred____________________?
A. from a metal wall from one medium to another
B. from heating an itermediate material and then heating the air from this material
C. by direct mixing
D. heat is transferred by bleeding some gases from furnace
E. none of the above
Answer» B. from heating an itermediate material and then heating the air from this material
Discussion
95.

The function of injector used in small capacity boilers is to____________________?
A. create vacuum
B. inject chemical solution in feed pump
C. pump water, similar to boiler feed pump
D. add make up water in the system
E. none of the above
Answer» D. add make up water in the system
Discussion
96.

In which of the following boilers, the draught in furnace is increased by utilising exhaust steam from engine__________________?
A. lancashire boiler
B. locomotive boiler
C. babcock and wilcox boiler
D. cochran boiler
E. benson boiler
Answer» C. babcock and wilcox boiler
Discussion
97.

In designing air preheater, the important design consideration is that_________________?
A. approach temperature should be as low as possible
B. handling and maintenance should be easier
C. heat transfer area should be optimum
D. stack gases should not be cooled to the dew point
E. none of the above
Answer» E. none of the above
Discussion
98.

With increase in load, convection superheater has_______________________?
A. drooping characteristic
B. linear characterisstic
C. rising characteristic
D. flat characteristic
E. none of the above
Answer» D. flat characteristic
Discussion
99.

The heat loss in a boiler takes place in the form of________________?
A. heat carried away by flue gases
B. heat carried away by ash
C. moisture present in fuel and steam formed by combustion of hydrogen in fuel
D. radiation
E. all of the above
Answer» F.
Discussion
100.

The overall efficiency of thermal power plant is________________?
A. boiler efficiency, turhine efficiecny, generator efficiency
B. all the three above plus gas cycle efficiency
C. carnot cycle efficiency
D. regenerative cycle efficiency
E. rankine cycle efficiency
Answer» B. all the three above plus gas cycle efficiency
Discussion