Explore topic-wise MCQs in Mechanical Engineering Questions.

This section includes 475 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.

Practically heat and work are completely interchangeable forms of energy
A. True
B. False
Answer» C.
Discussion
52.

Two reversible adiabatic paths
A. can intersect with each other
B. cannot intersect with each other
C. may intersect or may not intersect
D. none of the above
Answer» C. may intersect or may not intersect
Discussion
53.

The thermodynamic cycle in which net heat is transferred to the system and a net work is transferred from the system is called as
A. refrigeration cycle
B. heat engine cycle
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
54.

Which of the following is NOT the heat engine cycle
A. refrigerator
B. stem power plant
C. mass of gas confined in a cylinder and piston machine
D. none of the above
Answer» B. stem power plant
Discussion
55.

General gas equation is____________________?
A. PV=nRT
B. PV=mRT
C. PV = C
D. PV=KiRT
E. Cp-Cv = Wj
Answer» C. PV = C
Discussion
56.

Which of the following can be regarded as gas so that gas laws could be applicable, within the commonly encountered temperature limits ?
A. 02, N2, steam, C02
B. Oz, N2, water vapour
C. S02, NH3, C02, moisture
D. 02, N2, H2, air
E. steam vapours, H2, C02
Answer» E. steam vapours, H2, C02
Discussion
57.

The ratio of partial pressure of water vapour in a mixture to the saturation pressure of water at the same temperature of the mixture is called as
A. humidity
B. partial humidity
C. specific humidity
D. relative humidity
Answer» E.
Discussion
58.

According to Gay-Lussac law for a perfect gas, the absolute pressure of given mass varies directly as____________________?
A. temperature
B. absolute
C. absolute temperature, if volume is kept constant
D. volume, if temperature is kept constant
E. remains constant,if volume and temperature are kept constant
Answer» D. volume, if temperature is kept constant
Discussion
59.

What is the specific humidity?
A. the ratio of the mass of water vapour to the mass of the total mixture of air and water vapour
B. the ratio of the mass of dry air to the mass of the total mixture of air and water vapour
C. the ratio of the mass of dry air to the mass of water vapour in a mixture of air and water vapour
D. the ratio of the mass of water vapour to the mass of dry air in a mixture of air and water vapour
Answer» E.
Discussion
60.

The boiler in which the tubes are surrounded by hot gases is called as
A. fire tube boiler
B. water tube boiler
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
61.

Which type of function the entropy is?
A. a path function
B. a point function
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
62.

The properties of a system whose values depend upon mass of the system are called as
A. intensive properties
B. extensive properties
C. dependent properties
D. massive properties
Answer» C. dependent properties
Discussion
63.

If a heat engine produces net work output by exchanging heat with only one reservoir, then the heat engine will be,
A. perpetual motion machine of first kind (PMM1)
B. perpetual motion machine of second kind (PMM2)
C. perpetual motion machine of third kind (PMM3)
D. none of the above
Answer» C. perpetual motion machine of third kind (PMM3)
Discussion
64.

What is the formula for number of kg moles (n) of a gas? If, m = mass of gas in kg. μ = molecular weight in kg / kg mole
A. n = m . μ
B. n = m / μ
C. n = μ / m
D. none of the above
Answer» C. n = μ / m
Discussion
65.

The entropy is
A. an intensive property
B. an extensive property
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
66.

Carnot cycle contains two reversible adiabatic process and
A. two reversible isentropic processes
B. two reversible isobaric processes
C. two reversible isochoric processes
D. two reversible isothermal processes
Answer» E.
Discussion
67.

Isentropic (Entropy S=constant) process is also
A. a reversible isothermal process
B. a reversible adiabatic process
C. a reversible isobaric process
D. a reversible isochoric process
Answer» C. a reversible isobaric process
Discussion
68.

How is the entropy change of any irreversible process estimated, when the process is connecting two equilibrium points A and B?
A. by replacing the original process by reversible zigzag path containing reversible adiabatic followed by isothermal and then again reversible adiabatic
B. by replacing a reversible path between the same equilibrium points A and B
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
69.

What is the effect on temperature of an ideal gas, when it undergoes a Joule-Kelvin expansion?
A. temperature increases
B. temperature decreases
C. first temperature increases and then decreases isenthalpically
D. no change in temperature
Answer» E.
Discussion
70.

Which is a state of a substance from which a phase change occurs without a change of pressure or temperature?
A. pure state
B. phase state
C. saturation state
D. critical state
Answer» D. critical state
Discussion
71.

The compression ratio cannot be increased beyond certain limit, because it results to
A. auto-ignition of fuel
B. detonation
C. engine knocking
D. all of the above
Answer» E.
Discussion
72.

How is the capacity of vapour power plant expressed?
A. in terms of heat rate
B. in terms of steam rate
C. in terms of work output
D. none of the above
Answer» C. in terms of work output
Discussion
73.

Sometimes the pump work in vapour power cycle is neglected because
A. the pump work in not considered in efficiency of vapour power cycle
B. the pump work is very small compared to the heat addition
C. the pump work is very small compared to the turbine work
D. none of the above
Answer» C. the pump work is very small compared to the turbine work
Discussion
74.

How is the heat added in the Otto cycle?
A. reversibly at constant pressure
B. irreversibly at constant pressure
C. reversibly at constant volume
D. irreversibly at constant volume
Answer» D. irreversibly at constant volume
Discussion
75.

Use of gasoline blend like gasoline mixed with tetraethyl lead in internal combustion engine
A. increases the octane rating of the fuel
B. allows engine to operate at higher compression ratio
C. avoids auto-ignition of fuel
D. all of the above
Answer» E.
Discussion
76.

The ideal refrigeration cycle is like
A. Carnot cycle
B. Reversed Carnot cycle
C. Rankine cycle
D. Reversed Rankine cycle
Answer» C. Rankine cycle
Discussion
77.

The degree of saturation varies between
A. 1 to infinity
B. 0 to infinity
C. 0 to 1
D. none of the above
Answer» D. none of the above
Discussion
78.

Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle?
A. throttling valve
B. capillary tube
C. either throttling valve or capillary tube
D. none of the above
Answer» D. none of the above
Discussion
79.

What is the degree of saturation?
A. the ratio of the actual relative humidity to the saturated specific humidity at the same temperature
B. the ratio of the actual specific humidity to the saturated specific humidity at the same temperature
C. the ratio of the saturated specific humidity to the actual specific humidity at the same temperature
D. none of the above
Answer» C. the ratio of the saturated specific humidity to the actual specific humidity at the same temperature
Discussion
80.

What is the dead state of the system?
A. the state at which system is in pressure and temperature equilibrium with the surroundings
B. the state at which system is in chemical equilibrium with the surroundings
C. the state at which system must have zero velocity and minimum potential energy
D. all of the above
Answer» E.
Discussion
81.

Which among the following is an intensive property of a system?
A. Volume
B. Energy
C. Pressure
D. all of the above
Answer» D. all of the above
Discussion
82.

Comparing fire tube and water tube boilers, which boiler can produce comparatively higher pressure steam than another for the same capacity?
A. fire tube boiler
B. water tube boiler
C. both can produce steam at same pressure for the same capacity
D. none of the above
Answer» C. both can produce steam at same pressure for the same capacity
Discussion
83.

To maximize the work output at turbine, the specific volume of working fluid should be
A. as small as possible
B. as large as possible
C. constant throughout the cycle
D. none of the above
Answer» C. constant throughout the cycle
Discussion
84.

Work involved in a thermodynamic process is
A. a path function
B. a point function
C. a transfer function
D. none of the above
Answer» B. a point function
Discussion
85.

What is the criterion provided by Clausius inequality for the process which is impossible?
A. Cyclic ∫ (đQ/T) = 0
B. Cyclic ∫ (đQ/T) > 0
C. Cyclic ∫ (đQ/T) < 0
D. all above processes are possible
Answer» C. Cyclic ∫ (đQ/T) < 0
Discussion
86.

The characteristic of a material or a body which is taken as an indication of change in temperature is known as
A. Thermodynamics property
B. Thermostatic property
C. Thermometric property
D. none of the above
Answer» D. none of the above
Discussion
87.

Which condition is correct according to the entropy principle?
A. the entropy of an isolated system can never decreases
B. the entropy of a system remains constant only when the process is reversible
C. the entropy of a system increases when the process is irreversible
D. all of the above
Answer» E.
Discussion
88.

What is available energy (A. E.)
A. Energy supplied to a cyclic heat engine
B. Maximum energy utilized to produce maximum work from a certain heat supplied to a cyclic heat engine
C. Minimum heat energy rejected to sink by second law
D. Maximum heat energy rejected to sink by second law
Answer» C. Minimum heat energy rejected to sink by second law
Discussion
89.

Which loss does present in actual vapour power cycle at the exit of the boiler and at the entry of the turbine?
A. friction loss
B. constant pressure heat loss
C. both a. and b.
D. none of the above
Answer» D. none of the above
Discussion
90.

What is unavailable energy (U. E.)
A. Energy supplied to a cyclic heat engine
B. Maximum energy utilized to produce maximum work from a certain heat supplied to a cyclic heat engine
C. Minimum heat energy rejected to sink by second law
D. Maximum heat energy rejected to sink by second law
Answer» D. Maximum heat energy rejected to sink by second law
Discussion
91.

How can we differentiate Rankine cycle from Carnot cycle?
A. Heat addition process of Rankine cycle is reversible isothermal whereas heat addition process of Carnot cycle is reversible isobaric
B. Heat addition process of Rankine cycle is reversible isobaric whereas heat addition process of Carnot cycle is reversible isothermal
C. Heat addition process of Rankine cycle is reversible isentropic whereas heat addition process of Carnot cycle is reversible isothermal
D. both cycles are identical except the working fluid used
Answer» C. Heat addition process of Rankine cycle is reversible isentropic whereas heat addition process of Carnot cycle is reversible isothermal
Discussion
92.

How is the efficiency of the SI engine affected by change in specific heat ratio (γ) of the working fluid?
A. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working fluid
B. the efficiency of the engine decreases with increase in specific heat ratio (γ) of the working fluid
C. the efficiency of the engine does not affected by change in specific heat ratio (γ) of the working fluid
D. none of the above
Answer» B. the efficiency of the engine decreases with increase in specific heat ratio (γ) of the working fluid
Discussion
93.

For the same capacity engines, the compression ratio of diesel engine
A. is lower than the compression ratio of SI engine
B. is higher than the compression ratio of SI engine
C. is same as the compression ratio of SI engine
D. cannot say
Answer» C. is same as the compression ratio of SI engine
Discussion
94.

Rate of burning in the compression ignition engine can be controlled by
A. rate of injection of fuel
B. rate of air taken into carburetor
C. both a. and b.
D. none of the above
Answer» B. rate of air taken into carburetor
Discussion
95.

How is the heat added in the Diesel cycle?
A. reversibly at constant pressure
B. irreversibly at constant pressure
C. reversibly at constant volume
D. irreversibly at constant volume
Answer» B. irreversibly at constant pressure
Discussion
96.

What is the temperature at which the water vapour in the mixture of water vapour in air, starts condensing called?
A. condensation temperature
B. dew point temperature
C. vaporization temperature
D. all of the above
Answer» C. vaporization temperature
Discussion
97.

What is the result of superheating of vapour at the evaporator outlet?
A. no liquid droplets will travel to the compressor
B. the compressor discharge temperature increases
C. both a. and b.
D. none of the above
Answer» D. none of the above
Discussion
98.

The Brayton cycle which is used in aircraft, automotive is
A. a closed cycle
B. an open cycle
C. either closed or open cycle
D. cannot say
Answer» C. either closed or open cycle
Discussion
99.

Which expansion device is capable of regulating the flow of refrigerant according to the load on the evaporator?
A. capillary tube
B. throttle valve
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
100.

Which compressor is used, when volume flow rate of refrigerant is very large?
A. rotary compressor
B. reciprocating compressor
C. centrifugal compressor
D. none of the above
Answer» D. none of the above
Discussion