Thermodynamics MCQs Archives

61. The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same.

A. Kinematic viscosity

B. Work

C. Temperature

D. None of these

✅ The correct answer is option D.

62. Solid and liquid phases of a substance are in equilibrium at the

A. Critical temperature

B. Melting point

C. Freezing point

D. Both B and C

✅ The correct answer is option D.

63. Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of

A. Fusion

B. Vaporisation

C. Transition

D. None of these

✅ The correct answer is option C.

64. The unit of equilibrium constant of a chemical reaction is the same as that of

A. Molar concentration

B. Temperature

C. Internal energy

D. None of these

✅ The correct answer is option D.

65. Pick out the correct statement:

A. In an isothermal system, irreversible work is more than reversible work

B. Under reversible conditions, the adiabatic work is less than isothermal work

C. Heat, work, enthalpy and entropy are all ‘state functions’

D. Matter and energy can not be exchanged with the surroundings in a closed system

✅ The correct answer is option B.

66. At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero. This follows from the

A. Third law of thermodynamics

B. Second law of thermodynamics

C. Nernst heat theorem

D. Maxwell’s relations

✅ The correct answer is option A.

67. The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point.

A. Freezing

B. Triple

C. Boiling

D. Boyle

✅ The correct answer is option B.

68. Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the

A. Low pressure and high temperature

B. Low pressure and low temperature

C. High pressure and low temperature

D. High pressure and high temperature

✅ The correct answer is option B.

69. Cv is given by

A. (∂E/∂T)V

B. (∂E/∂V)T

C. (∂E/∂P)V

D. (∂V/∂T)P

✅ The correct answer is option A.

70. The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.

A. Lowest

B. Highest

C. Average

D. None of these

✅ The correct answer is option A.