In a steady flow process, the rate of

mass flow at inlet and outlet is same

Heat capacity of a substance is infinite. It means ___________

Heat is first given out and then taken out

The door of a domestic refrigerator is kept open while the switch is on. Then the room will ___________

Gets heated first and then cools

Which of the following is not a state function?

Work done by conservative force

Work done by non0conservative force

Assertion: When a glass of hot milk placed in a room is allowed to cool, its entropy decreases.Reason: Allowing the hot object to cool does not violate the second law of thermodynamics.

Assertion is true but the reason is false

Both assertion and reason are true and the reason is the correct explanation of the assertion

Both assertion and reason are true but the reason is not the correct explanation of the assertion

Assertion is true but the reason is false

Both assertion and reason are false

Heat interaction between a system and its surroundings

Does not depend on the choice of the system

Carnot cycle consists of ________.

2 isothermal and 2 isochoric processes.

2 isobaric and 2 adiabatic processes.

2 isobaric and 2 isochoric processes.

2 isothermal and 2 adiabatic processes.

A non-flow device compresses air isothermally at a temperature of 500°C from a pressure of 5 MPa to a final pressure of 15 MPa. If the device uses 200 kJ/kg of work input, then this process is:

either reversible or irreversible

If the work done on the system or by the system· is zero, which one of the following statements for a gas kept at a certain volume is correct?

Change in internal energy of the system is less than heat transferred.

Change in internal energy of the system is equal to flow of heat in or out of the system.

Change in internal energy of the system is less than heat transferred.

Change in internal energy of the system is more than the heat flow.

In steam tables, the entropy is shown a zero for

Saturated vapour at atmospheric pressure

Saturated liquid at atmospheric pressure

For the following T-s diagram pick the correct option.

This represents a heat pump with COP = 0.6; net work = 1237 kJ/kg.

This represents a heat engine with cycle efficiency = 0.6; net work = 1053 kJ/kg.

This represents a heat pump with COP = 0.6; net work = 1237 kJ/kg.

This represents a heat engine with cycle efficiency = 0.4; net work = 1053 kJ/kg.

This represents a refrigerator with COP = 0.4; net work = 702 kJ/kg.

425 + Mcqs in Thermodynamics in Graduate Aptitude Test (GATE) Page 1 McqOptions

1.	The mass of carbon per kg of flue gas is given by
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» B. [B].

Discussion

2.	One m3 of methane (CH4) requires 2m3 of oxygen and produces 1m3 of carbon dioxide and 2m3 of water or steam.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

3.	The most probable velocity of the gas molecules is given by
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» C. [C].

Discussion

4.	The root mean square velocity of the gas molecules is given by (where k = Boltzmann's constant, T = Absolute temperature, and m = Mass of one molecule of a gas)
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» D. [D].

Discussion

5.	In a steady flow process, the rate of
A.	heat transfer is constant
B.	work transfer is constant
C.	mass flow at inlet and outlet is same
D.	all of these
Answer» E.

Discussion

6.	Heat capacity of a substance is infinite. It means ___________
A.	Heat is given out
B.	Heat is taken out
C.	No change in temperature
D.	Heat is first given out and then taken out
Answer» D. Heat is first given out and then taken out

Discussion

7.	A Carnot engine working between 300 K and 600 K has a work output of 800 J per cycle. The amount of heat energy supplied to the engine from source per cycle is ___________
A.	1200J
B.	1600J
C.	2400J
D.	3200J
Answer» C. 2400J

Discussion

8.	The door of a domestic refrigerator is kept open while the switch is on. Then the room will ___________
A.	Get heated
B.	Ger neither heated nor cooled
C.	Gets cooled
D.	Gets heated first and then cools
Answer» B. Ger neither heated nor cooled

Discussion

9.	The inside and outside temperature of a refrigerator are 273K and 303K respectively. Assuming that refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be?
A.	10 J
B.	20 J
C.	30 J
D.	50 J
Answer» B. 20 J

Discussion

10.	Which of the following is not a state function?
A.	Work done at constant pressure
B.	Enthalpy
C.	Work done by conservative force
D.	Work done by non0conservative force
Answer» E.

Discussion

11.	Assertion: When a glass of hot milk placed in a room is allowed to cool, its entropy decreases.Reason: Allowing the hot object to cool does not violate the second law of thermodynamics.
A.	Both assertion and reason are true and the reason is the correct explanation of the assertion
B.	Both assertion and reason are true but the reason is not the correct explanation of the assertion
C.	Assertion is true but the reason is false
D.	Both assertion and reason are false
Answer» C. Assertion is true but the reason is false

Discussion

12.	Calculate the work done if temperature is changes from 0°C to 200°C at one atmosphere.
A.	100 cal
B.	200 cal
C.	400 cal
D.	800 cal
Answer» D. 800 cal

Discussion

13.	Which of the following parameters does not characterize the thermodynamic state of matter?
A.	Temperature
B.	Pressure
C.	Work
D.	Volume
Answer» D. Volume

Discussion

14.	A system, after passing through different states returns back to its original state, is called ___________
A.	Cyclic process
B.	Isothermal process
C.	Adiabatic process
D.	Isobaric process
Answer» B. Isothermal process

Discussion

15.	In a thermal process, the pressure of a fixed mass of a gas is changed in such a manner that the gas molecules give out the heat of 30J and work of 10J is done on the gas. If the initial internal energy of the gas was 40 J, then the final internal energy will be?
A.	30 J
B.	20 J
C.	60 J
D.	40 J
Answer» D. 40 J

Discussion

16.	Calculate the coefficient of performance of a refrigerator if it extracts 1200J of heat from the cold reservoir and releases 1800J of heat to the hot reservoir in each cycle?
A.	2
B.	3
C.	0.5
D.	1
Answer» B. 3

Discussion

17.	A thermometer graduated according to a linear scale reads a value x0, when in contact with boiling water and \(\frac{{{x_0}}}{3}\), when in contact with ice. What is the temperature of an object in °C, if this thermometer in the contact with the object reads \(\frac{{{x_0}}}{2}\)?
A.	35
B.	60
C.	40
D.	25
Answer» E.

Discussion

18.	A mass of 10 kg is suspended vertically by a rope from the roof. When a horizontal force is applied on the rope at some point, the rope deviated at an angle of 45° at the roof point. If the suspended mass is at equilibrium, the magnitude of the force applied is (g = 10 ms-2)
A.	200 N
B.	140 N
C.	70 N
D.	100 N
Answer» E.

Discussion

19.	A engine work on Carnot cycle between 727°C and 227°C. The efficiency of the engine is
A.	50%
B.	75.4%
C.	31.2%
D.	68.8%
Answer» B. 75.4%

Discussion

20.	A diatomic gas with rigid molecules does 10 J of work when expanded at constant pressure. What would be the heat energy absorbed by the gas, in this process?
A.	25 J
B.	35 J
C.	30 J
D.	40 J
Answer» C. 30 J

Discussion

21.	Internal energy associated with kinetic energy of molecules is ______.
A.	Nuclear Energy
B.	Chemical Energy
C.	Sensible Energy
D.	Latent Energy
Answer» D. Latent Energy

Discussion

22.	Heat interaction between a system and its surroundings
A.	Represents energy in transit
B.	Does not depend on the choice of the system
C.	Absolute zero temperature
D.	Below 0°C temperature
Answer» B. Does not depend on the choice of the system

Discussion

23.	If an enclosed gas is compressed to 60% of its original volume then by how much (in %) will its pressure increase, temperature remaining constant?
A.	40
B.	60
C.	33.3
D.	66.7
Answer» E.

Discussion

24.	A reaction is spontaneous when
A.	ΔG = -ve
B.	ΔH = -ve
C.	ΔS = +ve
D.	ΔS = -ve
Answer» B. ΔH = -ve

Discussion

25.	For a refrigerator the heat extracted from the reservoir is equal to? ('α' is the coefficient of performance of a refrigerator, 'Q1' is the heat released to the hot reservoir, and 'W' is the work done on the system–the refrigerant.)
A.	(1 + α)/Q1
B.	Q1/(1 + α)
C.	(1 + α)/(αQ1)
D.	αQ1/(1 + α)
Answer» E.

Discussion

26.	A diatomic gas does 80 J of work when compressed isobarically. The heat given to the gas during this process is
A.	700 J
B.	350 J
C.	280 J
D.	300 J
Answer» D. 300 J

Discussion

27.	Carnot cycle consists of ________.
A.	2 isothermal and 2 isochoric processes.
B.	2 isobaric and 2 adiabatic processes.
C.	2 isobaric and 2 isochoric processes.
D.	2 isothermal and 2 adiabatic processes.
Answer» E.

Discussion

28.	In thermodynamics, which of the following statements are true?1) Work is path independent function2) Work is a path-dependent function3) Work is the area under the curve in a PV diagram4) Work and heat energy are completely interchangeable
A.	1 & 4
B.	1 & 2
C.	3 & 4
D.	2 & 3
Answer» E.

Discussion

29.	A non-flow device compresses air isothermally at a temperature of 500°C from a pressure of 5 MPa to a final pressure of 15 MPa. If the device uses 200 kJ/kg of work input, then this process is:
A.	Impossible
B.	irreversible
C.	either reversible or irreversible
D.	reversible
Answer» B. irreversible

Discussion

30.	How much work (in kJ) does a cyclic heat engine do per cycle, if its efficiency is 0.75 and heat rejected per cycle is 40kJ?
A.	53.3
B.	30
C.	80
D.	120
Answer» E.

Discussion

31.	If the work done on the system or by the system· is zero, which one of the following statements for a gas kept at a certain volume is correct?
A.	Change in internal energy of the system is equal to flow of heat in or out of the system.
B.	Change in internal energy of the system is less than heat transferred.
C.	Change in internal energy of the system is more than the heat flow.
D.	Cannot be determined.
Answer» B. Change in internal energy of the system is less than heat transferred.

Discussion

32.	___________ is a device by which a system is made to undergo a cyclic process that results in conversion of heat to work.
A.	Refrigerator
B.	Heat engine
C.	Heat pump
D.	Heat Sink
Answer» C. Heat pump

Discussion

33.	In steam tables, the entropy is shown a zero for
A.	Saturated vapour at atmospheric pressure
B.	Saturated liquid at atmospheric pressure
C.	Saturated vapour at 0° C
D.	Saturated liquid at 0° C
Answer» E.

Discussion

34.	A Carnot engine works between the temperature 227° C and 127° C. If the work output of the engine is 104 J, then the amount of heat rejected to the sink will be:
A.	1 × 104 J
B.	2 × 104 J
C.	4 × 104 J
D.	5 × 104 J
Answer» D. 5 × 104 J

Discussion

35.	A refrigerator operates between 7°C and 27°C . What is it's coefficient of performance?
A.	14
B.	7
C.	27
D.	54
Answer» B. 7

Discussion

36.	A heat engine takes in 750J of heat from a hot reservoir and produces 450J of work in each cycle. What is its efficiency?
A.	0.75
B.	0.3
C.	0.5
D.	0.6
Answer» E.

Discussion

37.	For the following T-s diagram pick the correct option.
A.	This represents a heat engine with cycle efficiency = 0.6; net work = 1053 kJ/kg.
B.	This represents a heat pump with COP = 0.6; net work = 1237 kJ/kg.
C.	This represents a heat engine with cycle efficiency = 0.4; net work = 1053 kJ/kg.
D.	This represents a refrigerator with COP = 0.4; net work = 702 kJ/kg.
Answer» B. This represents a heat pump with COP = 0.6; net work = 1237 kJ/kg.

Discussion

38.	A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature T. Considering only translational and rotational modes, the total internal energy of the system is
A.	12 RT
B.	15 RT
C.	20 RT
D.	4 RT
Answer» C. 20 RT

Discussion

39.	A refrigerator operates between -3 °C and T °C. If its coefficient of performance is 9, then find T?
A.	300
B.	27
C.	127
D.	200
Answer» C. 127

Discussion

40.	An ideal gas engine operates in a Carnot cycle. It absorbs heat at a temperature T1 and exhausts heat at T2. The efficiency of this engine is:
A.	\(\frac{T_1 – T_2}{T_1}\)
B.	\(\frac{T_1+ T_2}{T_1}\)
C.	\(\frac{T_1 – T_2}{T_2}\)
D.	\(\frac{T_1 }{T_2}\)
Answer» B. \(\frac{T_1+ T_2}{T_1}\)

Discussion

41.	In a Carnot cycle _____________. (Where, Q1 is the heat absorbed by the gas from the reservoir at temperature T1 and Q2 is the Heat released by the gas to the reservoir at temperature T2.)
A.	Q1/Q2 = T1/T2
B.	Q1/Q2 = T2/T1
C.	(Q1-Q2)/Q2 = T1/T2
D.	(Q1-Q2)/Q2 = T2/T1
Answer» B. Q1/Q2 = T2/T1

Discussion

42.	A cylinder with fixed capacity of 67.2 lit contains helium gas at STP. The amount of heat needed to raise the temperature of the gas b 20°y C is: [Given that R = 8.31 J mol-1 K-1]
A.	350 J
B.	374 J
C.	748 J
D.	700 J
Answer» D. 700 J

Discussion

43.	In adiabatic process
A.	ΔQ < 0
B.	ΔQ > 0
C.	ΔQ = 0
D.	None of these
Answer» D. None of these

Discussion

44.	A Carnot engine has an efficiency of 1/6. When the temperature of the sink is reduced by 62°C, its efficiency is doubled. The temperatures of the source and the sink are, respectively,
A.	62°C, 124°C
B.	99°C, 37°C
C.	124°C, 62°C
D.	37°C, 99°C
Answer» C. 124°C, 62°C

Discussion

45.	An ideal gas heat engine operates in a Carnot Cycle, absorbing heat from a heat source as a hot reservoir at a temperature of 127°C. It rejects heat to the sink at a colder reservoir at a temperature of 87°C. Then the efficiency of the engine is nearly
A.	26%
B.	68%
C.	10%
D.	32%
Answer» D. 32%

Discussion

46.	For 100% efficiency of a Carnot engine the temperature of the source should be
A.	-273°C
B.	0°C
C.	273°C
D.	Infinite
Answer» E.

Discussion

47.	A thermally insulated vessel contains 150 g of water at 0°C. Then the air from the vessel is pumped out adiabatically. A fraction of water turns into ice and the rest evaporates at 0°C itself. The mass of evaporated water will be closest to:(Latent heat of vaporization of water = 2.10 × 106 J kg-1 and Latent heat of Fusion of water = 3.36 × 105 J kg-1)
A.	150 g
B.	20 g
C.	130 g
D.	35 g
Answer» C. 130 g

Discussion

48.	If the total number of possible microstates for a system of particles is 729, what is the entropy of the system?
A.	3 x 10-12 J/K
B.	3 x 10-22 J/K
C.	9 x 10-23 J/K
D.	6 x 10-21 J/K
Answer» D. 6 x 10-21 J/K

Discussion

49.	Boyle’s law is expressed as?
A.	PV = constant
B.	V/T = constant
C.	P/V = constant
D.	VT = constant
Answer» B. V/T = constant

Discussion

50.	In an ___________, work done by the gas is given by the equation W = P (V2 – V1).
A.	Isochoric process
B.	Isothermal
C.	Isobaric process
D.	Adiabatic
Answer» D. Adiabatic

Discussion

Explore topic-wise MCQs in Graduate Aptitude Test (GATE).

The mass of carbon per kg of flue gas is given by

One m3 of methane (CH4) requires 2m3 of oxygen and produces 1m3 of carbon dioxide and 2m3 of water or steam.

The most probable velocity of the gas molecules is given by

The root mean square velocity of the gas molecules is given by (where k = Boltzmann's constant, T = Absolute temperature, and m = Mass of one molecule of a gas)

In a steady flow process, the rate of

Heat capacity of a substance is infinite. It means ___________

A Carnot engine working between 300 K and 600 K has a work output of 800 J per cycle. The amount of heat energy supplied to the engine from source per cycle is ___________

The door of a domestic refrigerator is kept open while the switch is on. Then the room will ___________

The inside and outside temperature of a refrigerator are 273K and 303K respectively. Assuming that refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be?

Which of the following is not a state function?

Assertion: When a glass of hot milk placed in a room is allowed to cool, its entropy decreases.Reason: Allowing the hot object to cool does not violate the second law of thermodynamics.

Calculate the work done if temperature is changes from 0°C to 200°C at one atmosphere.

Which of the following parameters does not characterize the thermodynamic state of matter?

A system, after passing through different states returns back to its original state, is called ___________

In a thermal process, the pressure of a fixed mass of a gas is changed in such a manner that the gas molecules give out the heat of 30J and work of 10J is done on the gas. If the initial internal energy of the gas was 40 J, then the final internal energy will be?

Calculate the coefficient of performance of a refrigerator if it extracts 1200J of heat from the cold reservoir and releases 1800J of heat to the hot reservoir in each cycle?

A thermometer graduated according to a linear scale reads a value x0, when in contact with boiling water and \(\frac{{{x_0}}}{3}\), when in contact with ice. What is the temperature of an object in °C, if this thermometer in the contact with the object reads \(\frac{{{x_0}}}{2}\)?

A mass of 10 kg is suspended vertically by a rope from the roof. When a horizontal force is applied on the rope at some point, the rope deviated at an angle of 45° at the roof point. If the suspended mass is at equilibrium, the magnitude of the force applied is (g = 10 ms-2)

A engine work on Carnot cycle between 727°C and 227°C. The efficiency of the engine is

A diatomic gas with rigid molecules does 10 J of work when expanded at constant pressure. What would be the heat energy absorbed by the gas, in this process?

Internal energy associated with kinetic energy of molecules is ______.

Heat interaction between a system and its surroundings

If an enclosed gas is compressed to 60% of its original volume then by how much (in %) will its pressure increase, temperature remaining constant?

A reaction is spontaneous when

For a refrigerator the heat extracted from the reservoir is equal to? ('α' is the coefficient of performance of a refrigerator, 'Q1' is the heat released to the hot reservoir, and 'W' is the work done on the system–the refrigerant.)

A diatomic gas does 80 J of work when compressed isobarically. The heat given to the gas during this process is

Carnot cycle consists of ________.

In thermodynamics, which of the following statements are true?1) Work is path independent function2) Work is a path-dependent function3) Work is the area under the curve in a PV diagram4) Work and heat energy are completely interchangeable

A non-flow device compresses air isothermally at a temperature of 500°C from a pressure of 5 MPa to a final pressure of 15 MPa. If the device uses 200 kJ/kg of work input, then this process is:

How much work (in kJ) does a cyclic heat engine do per cycle, if its efficiency is 0.75 and heat rejected per cycle is 40kJ?

If the work done on the system or by the system· is zero, which one of the following statements for a gas kept at a certain volume is correct?

___________ is a device by which a system is made to undergo a cyclic process that results in conversion of heat to work.

In steam tables, the entropy is shown a zero for

A Carnot engine works between the temperature 227° C and 127° C. If the work output of the engine is 104 J, then the amount of heat rejected to the sink will be:

A refrigerator operates between 7°C and 27°C . What is it's coefficient of performance?

A heat engine takes in 750J of heat from a hot reservoir and produces 450J of work in each cycle. What is its efficiency?

For the following T-s diagram pick the correct option.

A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature T. Considering only translational and rotational modes, the total internal energy of the system is

A refrigerator operates between -3 °C and T °C. If its coefficient of performance is 9, then find T?

An ideal gas engine operates in a Carnot cycle. It absorbs heat at a temperature T1 and exhausts heat at T2. The efficiency of this engine is:

In a Carnot cycle _____________. (Where, Q1 is the heat absorbed by the gas from the reservoir at temperature T1 and Q2 is the Heat released by the gas to the reservoir at temperature T2.)

A cylinder with fixed capacity of 67.2 lit contains helium gas at STP. The amount of heat needed to raise the temperature of the gas b 20°y C is: [Given that R = 8.31 J mol-1 K-1]

In adiabatic process

A Carnot engine has an efficiency of 1/6. When the temperature of the sink is reduced by 62°C, its efficiency is doubled. The temperatures of the source and the sink are, respectively,

An ideal gas heat engine operates in a Carnot Cycle, absorbing heat from a heat source as a hot reservoir at a temperature of 127°C. It rejects heat to the sink at a colder reservoir at a temperature of 87°C. Then the efficiency of the engine is nearly

For 100% efficiency of a Carnot engine the temperature of the source should be

If the total number of possible microstates for a system of particles is 729, what is the entropy of the system?

Boyle’s law is expressed as?

In an ___________, work done by the gas is given by the equation W = P (V2 – V1).