CUET-PG SERIES Mechanical-engineering
Thermodynamics
18 previous year questions.
Volume: 18 Ques
Yield: Medium
High-Yield Trend
8
2025 10
2024 Chapter Questions 18 MCQs
01
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
Match List I with List II:
Choose the correct answer from the options given below:
| LIST I (Component) | LIST II (Equipment used in) |
| A. Draft Tube | III. Francis Turbine |
| B. Thermostatic Expansion Valve | II. Cold Storage |
| C. Feed Water Heater | I. Thermal Power Plant |
| D. Automatic Expansion Valve | IV. Central AC Plant |
1
(A)- (III), (B)- (II), (C)- (I), (D)- (IV)
2
(A)- (III), (B)- (IV), (C)- (I), (D)- (II)
3
(A)- (I), (B)- (II), (C)- (III), (D)- (IV)
4
(A)- (III), (B)- (IV), (C)- (II), (D)- (I)
02
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
Assertion (A): In heating and dehumidification of air, relative humidity of air decreases.
Reason (R): Sensible heating causes enthalpy to decrease.
In light of the above statements, choose the correct answer from the options given below.
Reason (R): Sensible heating causes enthalpy to decrease.
In light of the above statements, choose the correct answer from the options given below.
1
Both A and R are true and R is the correct explanation of A
2
Both A and R are true but R is NOT the correct explanation of A
3
A is true but R is false
4
A is false but R is true
03
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
In a simple saturated Vapour compression refrigeration cycle, the enthalpy at various state points are: 10 kJ/kg, 45 kJ/kg and 25 kJ/kg. The mass flow rate of refrigerant is 2 kg/s:
- The power consumption of compressor is 40 kJ/kg
- The refrigeration capacity is 70 kW
- The COP is 1.75
- Heat rejected in condenser is 110 kW
1
(A) and (D) only.
2
(A), (B) and (C) only
3
(A), (B), (C) and (D).
4
(B), (C) and (D) only.
04
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
For the same compression ratio and same heat supplied in Otto, Diesel and Dual cycles:
(A) Otto cycle has maximum efficiency.
(B) Diesel cycle has minimum heat rejected.
(C) Dual cycle has maximum heat rejected.
(D) Diesel cycle has maximum heat rejected.
Choose the correct answer from the options given below.
(A) Otto cycle has maximum efficiency.
(B) Diesel cycle has minimum heat rejected.
(C) Dual cycle has maximum heat rejected.
(D) Diesel cycle has maximum heat rejected.
Choose the correct answer from the options given below.
1
(A), (B) and (D) only
2
(A) and (D) only.
3
(A), (B) and (C) only.
4
(B) and (C) only.
05
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
With increase in pressure ratio in Brayton cycle the net work output
1
increases
2
decreases
3
initially increases reaches to a maximum and then decreases
4
initially decreases and then increases
06
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
A system at 500 K receives 7200 kJ/min of heat from a source at 1000 K The ambient temperature is 300 K The system and source temperature remain constant during heat transfer The decrease in available energy due to heat transfer through finite temperature difference is
1
5040 kJ/min
2
2880 kJ/min
3
2060 kJ/min
4
2160 kJ/min
07
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
Given below are two statements, one is labelled as Assertion (A) and the other one labelled as Reason (R):
Assertion (A): The Clausius statement of second law of thermodynamics states that it is impossible to transfer heat from a body at low temperature to a body at high temperature without the aid of external work.
Reason (R): Heat always flows from low temperature to high temperature.
In light of the above statements, choose the correct answer from the options given below:
Assertion (A): The Clausius statement of second law of thermodynamics states that it is impossible to transfer heat from a body at low temperature to a body at high temperature without the aid of external work.
Reason (R): Heat always flows from low temperature to high temperature.
In light of the above statements, choose the correct answer from the options given below:
1
Both (A) and (R) are true and (R) is the correct explanation of (A).
2
Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
3
(A) is true but (R) is false.
4
(A) is false but (R) is true.
08
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
Match List I with List II:
| LIST I | LIST II |
| A. Subcooled water | I. 1 bar and 134°C |
| B. Superheated steam | II. Dryness fraction = 1 and 100°C |
| C. Steam at critical state | III. 20°C and 1.01325 bar |
| D. Saturated steam | IV. 374.15°C and 220.8 bar |
Choose the correct answer from the options given below:
1
(A)-(I), (B)-(II), (C)-(III),(D)-(IV)
2
(A)-(II), (B)-(III),(C)-(I),(D)-(IV)
3
(A)-(III), (B)-(II),(C)-(IV),(D)-(I)
4
(A)-(III), (B)-(I), (C)-(IV),(D)-(II)
09
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
2 kg of air is contained in a closed system at a pressure of 2 bar and 0.5 m3. It undergoes an isobaric expansion till the final volume becomes 0.6 m3. The work transfer (in kJ) during the process is:
1
-20
2
-10
3
+20
4
+10
10
PYQ 2024
medium
mechanical-engineering ID: cuet-pg-
A thermo flask is
1
Closed system
2
Open system
3
Isolated system
4
Adiabatic closed system
11
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
The latent heat of vaporization at the critical point is
1
less than zero
2
greater than zero
3
equal to zero
4
equal to one
12
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
Match List-I with List-II
Choose the correct answer from the options given below:
| List-I | List-II |
|---|---|
| (A) Work done in a polytropic process | (IV) |
| (B) Work done in a steady flow process | (I) |
| (C) Heat transfer in a reversible adiabatic process | (II) Zero |
| (D) Work done in an isentropic process | (III) |
1
(A) (IV), (B) (1), (C) (III), (D) (II)
2
(A) (I), (B) (IV), (C) (II), (D) (III)
3
(A) (IV), (B) (I), (C) (II), (D) (III)
4
(A) (1), (B) (II), (C) (III), (D) (IV)
13
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
Which thermodynamics law predicts correctly the degree of completion of a chemical reaction?
1
Zeroth law
2
First law
3
Second law
4
Third law
14
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
A refrigerating machine working on a reversed Carnot cycle takes out 2 kW of heat from the system while working between temperature limits of 300K and 200K. The coefficient of performance and power consumed by the cycle will be respectively:
1
1 and 1 kW
2
2 and 1 kW
3
1 and 2 kW
4
2 and 2 kW
15
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
Consider the following statements:
(A) Availability is generally conserved.
(B) Availability can neither be negative nor positive.
(C) Availability is the maximum theoretical work obtainable.
(D) Availability can be destroyed in irreversibility's.
1
(A), and (B) only
2
(A), and (C) only
3
(B), and (D) only
4
(C) and (D) only
16
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
Gas contained in a closed system consisting of a piston-cylinder arrangement is expanded. Work done by the gas during expansion is 50 kJ. The decrease in internal energy of the gas during expansion is 30 kJ. The heat transfer during the process is equal to:
1
-20 kJ
2
+20 kJ
3
-80 kJ
4
+80 kJ
17
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
In a psychrometric chart, what does a vertical downward line represent?
1
Sensible cooling process
2
Adiabatic saturation process
3
Humidification process
4
Dehumidification process
18
PYQ 2025
medium
mechanical-engineering ID: cuet-pg-
Match List-I with List-II
Choose the correct answer from the options given below:
| List-I (Details of the processes of the cycle) | List-II (Name of the cycle) |
|---|---|
| (A) Two adiabatic, one isobaric and two isochoric | (I) Diesel |
| (B) Two adiabatic and two isochoric | (II) Carnot |
| (C) Two adiabatic, one isobaric and one isochoric | (III) Dual |
| (D) Two adiabatics and two isothermals | (IV) Otto |
1
(A) (1), (B) (II), (C) (III), (D) (IV)
2
(A) (1), (B) (III), (C) (II), (D) (IV)
3
(A) (1), (B) (II), (C) (IV), (D) (III)
4
(A) (III), (B) (IV), (C) (I), (D) (II)