# 439 Thermodynamic MCQ For All Mechanical Exams

51)The operation of a machine that utilizes the internal energy of only one TER, thus violating second law is called

1. a) PMM0
2. b) PMM1
3. c) PMM2
4. d) none of the mentioned

Ans-B

52)Coefficient of performance(COP) is defined as

1. a) heat leakage/work input
2. b) work input/heat leakage
3. c) latent heat of condensation/work input
4. d) work input/latent heat of condensation

Ans-A

53)A heat transfer process approaches reversibility as the temperature difference between two bodies approaches

1. a) infinity
2. b) zero
3. c) -1
4. d) 1

Ans-B

54)The continual motion of a movable device in the complete absence of friction is known as

1. a) PMM2
2. b) PMM3
3. c) PMM1
4. d) PMM0

Ans-B

55)A process will be reversible if it has

1. a) no dissipative effects
2. b) dissipative effects
3. c) depends on the given conditions
4. d) none of the mentioned

Ans-B

56)Internal irreversibility is caused by

1. a) internal dissipative effects
2. b) friction, turbulence
3. c) electrical resistance, magnetic hysteresis
4. d) all of the mentioned

Ans-D

57)A reversible cycle has following processes.

1. a) 4 isothermal processes
3. c) 2 isothermal and 2 adiabatic processes
4. d) none of the mentioned

Ans-C

58)The correct sequence of the processes taking place in a carnot cycle is

Ans-D

59)The reversed heat engine takes heat from a ___ temperature body, then discharges it to a ___ temperature body and ___ an inward flow of network.

3. c) high, low, gives
4. d) low, high, gives

Ans-B

60)Efficiency of a reversible heat engine is given by

1. a) 1-(T1/T2)
2. b) 1-(T2/T1)
3. c) (T1/T2)-1
4. d) (T2/T1)-1

Ans-B

61)For a reversible refrigerator, Coefficient of Performance is given by

1. a) T2/(T1-T2)
2. b) T1/(T1-T2)
3. c) T2/(T2-T1)
4. d) T1/(T2-T1)

Ans-A

62)For a reversible heat pump, COP is given by

1. a) T2/(T1-T2)
2. b) T1/(T1-T2)
3. c) T2/(T2-T1)
4. d) T1/(T2-T1)

Ans-B

63)The absolute thermodynamic temperature scale is also known as

1. a) celsius scale
2. b) kelvin scale
3. c) fahrenheit scale
4. d) none of the mentioned

Ans-B

64)In defining the temperature scale, the standard reference point is taken as

1. a) zero kelvin
2. b) boiling point of water
3. c) triple point of water
4. d) none of the mentioned

Ans-C

65)When the heat transferred isothermally between the given _____ decreases, the temperature ____

1. a) isotherms, increases
2. b) isotherms, decreases

Ans-D

66)If a system undergoes a reversible isothermal process without transfer of heat, the temperature at which this process takes place is called

1. a) absolute zero
2. b) triple point of water
3. c) boiling point of water
4. d) none of the mentioned

Ans-A

67)A definite zero point ___ on the absolute temperature scale but this point ___ be reached ___ violation of the second law.

1. a) doesnot, can, without
2. b) exists, cannot, without
3. c) exists, can, with
4. d) none of the mentioned

Ans-B

68)Which law is stated here, “It is impossible to reduce any system to the absolute zero of temperature in a finite number of operations.

1. a) first law of thermodynamics
2. b) second law of thermodynamics
3. c) third law of thermodynamics
4. d) none of the mentioned

Ans-C

69)The Kelvin temperature is numerically equal to the _____ and may be measured by means of a _____

1. a) gas temperature, liquid thermometer
2. b) ideal gas temperature, gas thermometer
3. c) ideal gas temperature, liquid thermometer
4. d) none of the mentioned

Ans-B

70)According to the Clausius’ theorem, the cyclic integral of ____ for a reversible cycle is zero.

1. a) dW/dT
2. b) dH/dT
3. c) dQ/dT
4. d) dE/dT

Ans-C

71)The efficiency of a general cycle will be _____ the efficiency of a reversible cycle.

1. a) equal to
2. b) less than
3. c) equal to or greater than
4. d) equal to or less than

Ans-D

72)Which of the following is known as the inequality of Clausius?

1. a) cyclic integral of dQ/T<=0
2. b) cyclic integral of dQ/T>=0
3. c) cyclic integral of dW/T<=0
4. d) cyclic integral of dW/T>=0

Ans-A

73) If the cyclic integral of dQ/T is zero then the cycle is

1. a) irreversible but not possible
2. b) irreversible but possible
3. c) impossible
4. d) reversible

Ans-D

74)If the cyclic integral of dQ/T is less than zero then the cycle is

1. a) irreversible but not possible
2. b) irreversible and possible
3. c) impossible
4. d) reversible

Ans-B

75)If the cyclic integral of dQ/T is greater than zero then the cycle is

1. a) irreversible but not possible
2. b) irreversible but possible
3. c) impossible
4. d) reversible

Ans-C

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