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.

1.

The value of the product of molecular weight and the gas characteristic constant for all the gases in M.K.S. unit is______________________?
A. 29.27 kgfm/mol°K
B. 8314kgfm/mol°K
C. 848kgfm/mol°K
D. 427kgfm/mol°K
E. 735 kgfm/mol°K
Answer» D. 427kgfm/mol°K
Discussion
2.

One watt is equal to__________________?
A. 1 Nm/s
B. 1 N/mt
C. 1 Nm/hr
D. 1 kNm/hr
E. 1 kNm/mt
Answer» B. 1 N/mt
Discussion
3.

For which of the following substances, the gas laws can be used with minimum error_________________?
A. dry steam
B. wet steam
C. saturated steam
D. superheated steam
E. steam at atmospheric pressure
Answer» E. steam at atmospheric pressure
Discussion
4.

If a certain amount of dry ice is mixed with same amount of water at 80°C, the final temperature of mixture will be__________________?
A. 80°C
B. 0°C
C. 40°C
D. 20°C
E. 60°C
Answer» C. 40°C
Discussion
5.

In an isothermal process, the internal energy of gas molecules________________?
A. increases
B. decreases
C. remains constant
D. may increase/decrease depending on the properties of gas
E. shows unpredictable behaviour
Answer» D. may increase/decrease depending on the properties of gas
Discussion
6.

Solids and liquids have___________________?
A. one value of specific heat (ft) two values of specific heat
B. three values of specific heat
C. no value of specific heat
D. one value under some conditions and two values under other conditions
Answer» B. three values of specific heat
Discussion
7.

The index of compression n tends to reach ratio of specific heats y when____________________?
A. flow is uniform and steady
B. process is isentropic
C. process is isothermal
D. process is isentropic and specific heat does not change with temperature
E. process is isentropic and specific heat changes with temperature
Answer» E. process is isentropic and specific heat changes with temperature
Discussion
8.

Which of the following parameters is constant for a mole for most of the gases at a given temperature and pressure___________________?
A. enthalpy
B. volume
C. mass
D. entropy
E. specific volume
Answer» C. mass
Discussion
9.

The term N.T.P. stands for________________________?
A. nominal temperature and pressure
B. natural temperature and pressure
C. normal temperature and pressure
D. normal thermodynamic practice
E. normal thermodynamic pressure
Answer» D. normal thermodynamic practice
Discussion
10.

Work done in an adiabatic process between a given pair of end states depends on__________________?
A. the end states only
B. particular adiabatic process
C. the value of index n
D. the value of heattransferred
E. mass of the system
Answer» B. particular adiabatic process
Discussion
11.

An electric current I is passing through a resistor in contact with a reservoir. The internal energy of the resistor is constant. Heat generated is absorbed by surrounding at temperature T0. What will be the effect on entropy of the universe?
A. Entropy of the universe is always constant
B. The process increases the the entropy of the universe
C. The process decreases the the entropy of the universe
D. cannot say
Answer» C. The process decreases the the entropy of the universe
Discussion
12.

Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant________________?
A. pressure
B. temperature
C. volume
D. internal energy
E. entropy
Answer» B. temperature
Discussion
13.

How is heat transfer associated with entropy transfer?
A. the entropy transfer takes places along with heat flow in the direction of heat transfer
B. the entropy transfer takes places along with heat flow in the opposite direction of heat transfer
C. the entropy transfer does not take place along with heat transfer
D. none of the above
Answer» B. the entropy transfer takes places along with heat flow in the opposite direction of heat transfer
Discussion
14.

Thermal power plant works on______________?
A. Carnot cycle
B. Joule cycle
C. Rankine cycle
D. Otto cycle
E. Brayton cycle
Answer» D. Otto cycle
Discussion
15.

The law of degradation of energy states that
A. the energy is always conserved quantity wise
B. the energy is always conserved quality wise
C. the energy is always degraded quantity wise
D. the energy is always degraded quality wise
Answer» E.
Discussion
16.

The temperature of a substance at which the vapour pressure is equal to 760 mm Hg is called as
A. normal vapour point
B. normal boiling point
C. normal pressure point
D. none of the above
Answer» C. normal pressure point
Discussion
17.

When system gains entropy from the surrounding, what will be the effect on the molecules of the system?
A. molecular disorder increases
B. molecular disorder decreases
C. no change on molecular system
D. none of the above
Answer» B. molecular disorder decreases
Discussion
18.

What is the entropy transfer associated with work?
A. positive entropy transfer
B. negative entropy transfer
C. no entropy transfer
D. all of the above
Answer» D. all of the above
Discussion
19.

What is the entropy generation?
A. increase in the entropy of a system due to internal irreversibility
B. decrease in the entropy of a system due to internal irreversibility
C. no change in entropy of a system
D. none of the above
Answer» B. decrease in the entropy of a system due to internal irreversibility
Discussion
20.

Which law of thermodynamics expresses that the energy is always conserved quantity wise?
A. First law
B. Second law
C. Third law
D. none of the above
Answer» B. Second law
Discussion
21.

In which condition can real gas closely obey the ideal gas equation?
A. pressure is very small and temperature is very high
B. pressure is very high and temperature is very low
C. both pressure and temperature are very high
D. both pressure and temperature are very low
Answer» B. pressure is very high and temperature is very low
Discussion
22.

The temperature at which a pure liquid transforms into vapour at constant pressure is called as
A. vaporisation temperature
B. normal temperature
C. saturation temperature
D. none of the above
Answer» D. none of the above
Discussion
23.

In ideal regenerative cycle (saturated steam Rankine cycle), the heat addition takes place
A. from lowest temperature to highest temperature
B. at constant pressure
C. at constant temperature
D. none of the above
Answer» D. none of the above
Discussion
24.

What is a pure substance?
A. a homogeneous mixture of two substances of same composition
B. a substance with constant chemical composition throughout its mass
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
25.

Which of the following laws is applicable for the behavior of a perfect gas__________________?
A. Boyle’s law
B. Charles’law
C. Gay-Lussac law
D. all of the above
E. Joule’s law
Answer» E. Joule’s law
Discussion
26.

Gases have___________________?
A. only one value of specific heat
B. two values of specific heat
C. three values of specific heat
D. no value of specific heat
E. under some conditions one value and sometimes two values of specific heat
Answer» C. three values of specific heat
Discussion
27.

Atmospheric pressure is equal to____________?
A. 1.013 bar
B. 760mm of Hg
C. 101.3KN/m2
D. All of these
Answer» E.
Discussion
28.

What is a free-shaft turbine?
A. the separate turbine which is used only to run compressor
B. the separate turbine which is placed on another shaft on which the compressor is not run
C. the separate turbine which is used only to run condenser
D. all of the above
Answer» C. the separate turbine which is used only to run condenser
Discussion
29.

In free expansion of gas, the work transfer is
A. negative
B. zero
C. positive
D. none of the above
Answer» C. positive
Discussion
30.

I kgf/cm2 is equal to________________?
A. 760 mm Hg
B. zero mm Hg
C. 735.6 mm Hg
D. 1 mm Hg
E. lOOmmHg
Answer» D. 1 mm Hg
Discussion
31.

The following cycle is used for air craft refrigeration___________________?
A. Brayton cycle
B. Joule cycle
C. Carnot cycle
D. Bell-Coleman cycle
E. Reversed-Brayton cycle
Answer» F.
Discussion
32.

Which among the following systems undergo/es work transfer?
A. Current flowing through the resistor
B. A shaft rotated by a motor
C. both a. and b.
D. none of the above
Answer» D. none of the above
Discussion
33.

What is the effect of regeneration on mean temperature of heat addition in Brayton cycle?
A. mean temperature of heat addition decreases because of regeneration
B. mean temperature of heat addition increases because of regeneration
C. mean temperature of heat addition is not affected by use of regenerator
D. none of the above
Answer» C. mean temperature of heat addition is not affected by use of regenerator
Discussion
34.

In the Joule-Kelvin expansion of a gas, what should be the initial state of gas to obtain maximum cooling effect?
A. the initial state of the gas should lie in cooling region
B. the initial state of the gas should lie in heating region
C. the initial state of the gas should lie on inversion curve
D. none of the above
Answer» D. none of the above
Discussion
35.

The statement that molecular weights of all gases occupy the same volume is known as________________?
A. Avogadro’s hypothesis
B. Dalton’s law
C. Gas law
D. Law of thermodynamics
E. Joule’s law
Answer» B. Dalton’s law
Discussion
36.

Which refrigerant is widely used in refrigeration facilities of food as cooling of fresh vegetables, dairy products, meat and fish and similar process industries?
A. sulphur dioxide
B. ethyl chloride
C. propane
D. ammonia
Answer» E.
Discussion
37.

What is the desirable characteristic of a refrigerant?
A. it should not be toxic
B. it should not be non-corrosive
C. it should have minimum enthalpy of vaporization
D. all of the above
Answer» B. it should not be non-corrosive
Discussion
38.

Isochoric process is one in which___________________?
A. free expansion takes place
B. very little mechanical work is done by the system
C. no mechanical work is done by the system
D. all parameters remain constant
E. mass and energy transfer do not take place
Answer» D. all parameters remain constant
Discussion
39.

Heat transfer is an irreversible process if
A. the temperature difference between the two bodies is infinitesimally small
B. the temperature difference between the two bodies is finite
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
40.

In a non-flow reversible process for which p = (- 3V+ 15) x 105N/m2,V changes from 1 m to 2 m3. The work done will be about_______________?
A. 100 xlOO5 joules
B. lxlO5 joules
C. 10 xlO5 joules
D. 10 xlO5 kilo joules
E. 10xl04kiojoules
Answer» D. 10 xlO5 kilo joules
Discussion
41.

Exergy is not conserved but destroyed in the process. What is the reason behind this?
A. reversibility
B. irreversibility
C. both reversibility and irreversibility
D. none of the above
Answer» C. both reversibility and irreversibility
Discussion
42.

Considering relation between Kelvin-Planck and Clausius statement, if one statement between the two is violated then
A. other one may be or may not be violated
B. other one is also violated
C. other one must be correct
D. none of the above
Answer» C. other one must be correct
Discussion
43.

Suppose the entropy of a system increases with increase in some parameter x. What will be the effect on entropy at equilibrium state of the system, when the parameter will be decreased?
A. the entropy decrease
B. the entropy increase
C. the entropy remains constant
D. Condition is wrong; entropy does not change with any parameter.
Answer» D. Condition is wrong; entropy does not change with any parameter.
Discussion
44.

What is the perfect condition for dehumidification of air?
A. air is heated above its dew point temperature
B. air is cooled up to its dew point temperature
C. air is heated below its dew point temperature
D. air is cooled below its dew point temperature
Answer» E.
Discussion
45.

The term which can differentiate thermodynamics from other sciences is ____.
A. Pressure
B. Temperature
C. Mass
D. none of the above
Answer» C. Mass
Discussion
46.

The energy of an isolated system
A. is always decreasing
B. is always constant
C. is always increasing
D. none of the above
Answer» C. is always increasing
Discussion
47.

The thermodynamic work done by the system on the surrounding is considered as ____.
A. positive
B. negative
C. neutral
D. none of the above
Answer» B. negative
Discussion
48.

When the heat transfer into a system is more than the work transfer out of the system, then
A. the internal energy of the system remains constant
B. the internal energy of the system decreases
C. the internal energy of the system increases
D. none of the above
Answer» D. none of the above
Discussion
49.

A thermal energy reservoir (TER) has
A. a finite heat capacity
B. an infinite heat capacity
C. a finite mass
D. none of the above
Answer» C. a finite mass
Discussion
50.

First law of thermodynamics provides
A. a statement that energy balance occurs when a system undergoes the change of state or the process
B. a statement about whether the change of state or the process is at all feasible or not
C. both a. and b.
D. none of the above
Answer» B. a statement about whether the change of state or the process is at all feasible or not
Discussion