thermodynamics MCQs – Page 2

Practise focused thermodynamics questions with marked answers for exam preparation and subject revision.

thermodynamics Mcqs
51. The following cycle is used for air craft refrigeration___________________?
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A. Brayton cycle

B. Joule cycle

C. Reversed-Brayton cycle

D. Carnot cycle

E. Bell-Coleman cycle

52. A gas is compressed in a cylinder by a movable piston to a volume one-half its original volume. During the process 300 kJ heat left the gas and internal energy remained same. The work done on gas in Nm will be___________________?
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A. 300 Nm

B. 300,000 Nm

C. 3000 Nm

D. 30,000 Nm

E. 30 Nm

53. The door of a running refrigerator inside a room was left open____________________?
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A. ch of the following statements is correct ?

54. A perfect gas at 27C is heated at constant pressure till its volume is double. The final temperature is________________?
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A. 327C

B. 54C

C. 108C

D. 654C

E. 600C

55. If a system after undergoing a series of processes, returns to the initial state then__________________?
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A. its entropy will change due to irreversibility

B. process is thermodynamically in equilibrium

C. process is executed in closed system cycle

D. no work will be done by the system

E. sum of heat and work transfer will be zero
56. The index of compression n tends to reach ratio of specific heats y when____________________?
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A. process is isentropic and specific heat does not change with temperature

B. flow is uniform and steady

C. process is isentropic

D. process is isentropic and specific heat changes with temperature

E. process is isothermal

57. According to Avogadros law, for a given pressure and temperature, each molecule of a gas_________________?
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A. occupies volume proportional to its molecular weight

B. occupies volume proportional to its specific weight

C. occupies volume inversely proportional to its molecular weight

D. occupies volume inversely proportional to its specific weight

E. occupies same volume
58. The unit of pressure in S.I. units is____________________?
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A. dynes per square cm

B. bars

C. kg/cm2

D. mm of water column

E. pascal
59. Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant________________?
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A. volume

B. entropy

C. pressure

D. internal energy

E. temperature

60. Universal gas constant is defined as equal to product of the molecular weight of the gas and_______________?
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A. gas constant

B. specific heat at constant pressure

C. ratio of two specific heats

D. specific heat at constant volume

E. unity.

61. In an isothermal process, the internal energy________________?
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A. first decreases and then increases

B. increases

C. decreases

D. remains constant

E. first increases and then decreases

62. Work done is zero for the following process_________________?
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A. free expansion

B. none of the above

C. all Of the above

D. throttling

E. constant volume

63. Which of the following can be regarded as gas so that gas laws could be applicable, within the commonly encountered temperature limits ?
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A. steam vapours, H2, C02

B. 02, N2, H2, air

C. 02, N2, steam, C02

D. S02, NH3, C02, moisture

E. Oz, N2, water vapour

64. The first law of thermodynamics is the law of_________________?
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A. conservation of energy

B. conservation of momentum

C. conservation of mass

D. conservation of heat

E. conservation of temperature

65. Compressed air coming out from a punctured football___________________?
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A. attains atmospheric temperature

B. may become hotter or cooler depend-ing upon the humidity of the surrounding air

C. becomes hotter

D. becomes cooler1

E. remains at the same temperature

66. First law of thermodynamics furnishes the relationship between______________________?
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A. various thermodynamic processes

B. heat, work and properties of the system

C. heat and internal energy

D. various properties of the system

E. heat and work

67. General gas equation is____________________?
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A. PV=KiRT

B. PV=nRT

C. Cp-Cv = Wj

D. PV = C

E. PV=mRT
68. The value of n = 1 in the poly tropic process indicates it to be __________________?
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A. irreversible process

B. isothermal process

C. reversible process

D. adiabatic process

E. free expansion process

69. An isolated system is one in which_____________________?
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A. mass does not cross boundaries of the system, though energy may do so

B. neither mass nor energy crosses the boundaries of the system

C. both energy and mass cross the boundaries of the system

D. mass crosses the boundary but not the energy

E. thermodynamic reactions do not occur

70. If a fluid expands suddenly into vacuum through an orifice of large dimension, then such a process is called___________________?
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A. free expansion

B. adiabatic expansion

C. throttling

D. parabolic expansion

E. hyperbolic expansion

71. One watt is equal to__________________?
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A. 1 N/mt

B. 1 kNm/hr

C. 1 Nm/s

D. 1 Nm/hr

E. 1 kNm/mt

72. Characteristic gas constant of a gas is equal to______________________?
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A. Cv/Cp

B. Cp x Cv

C. C/Cv

D. Cp Cv

E. Cp + Cv

73. Which of the following is an irreversible cycle_____________________?
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A. all of the above

B. carnot

C. ericsson

D. none of the above

E. Stirling

74. The specific heat of air increases with increase in __________________?
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A. temperature

B. pressure

C. both pressure and temperature

D. variation of its constituents

E. air flow

75. Change in enthalpy of a system is the heat supplied at___________________?
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A. constant entropy

B. constant pressure

C. constant volume

D. N.T.P. condition

E. constant temperature

76. A diathermic wall is one which____________________?
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A. permits thermal interaction

B. discourages thermal interaction

C. does not exist

D. prevents thermal interaction

E. encourages thermal interaction

77. The behaviour of gases can be fully determined by___________________?
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A. 3 laws

B. 2 laws

C. 4 laws

D. 1 law

78. Temperature of a gas is produced due to________________?
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A. kinetic energy of molecules

B. its heating value

C. repulsion of molecules

D. surface tension of molecules

E. attraction of molecules

79. Which of the following quantities is not the property of the system__________________?
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A. pressure

B. specific volume

C. density

D. temperature

E. heat
80. 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_______________?
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A. 100 xlOO5 joules

B. 10 xlO5 kilo joules

C. lxlO5 joules

D. 10xl04kiojoules

E. 10 xlO5 joules
81. According to Daltons law, the total pres sure of the mixture of gases is equal to________________?
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A. greater of the partial pressures of all

B. atmospheric pressure

C. average of the partial pressures of all

D. sum of the partial pressures of all

E. sum of the partial pressures of all divided by average molecular weight

82. Which law states that the internal energy of a gas is a function of temperature__________________?
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A. there is no such law

B. Regnaults law

C. Joules law

D. Charles law

E. Boyles law

83. Mixture of ice and water form a________________________?
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A. open system

B. isolated system

C. closed system

D. heterogeneous system

E. thermodynamic system.

84. Carnot cycle efficiency depends upon________________?
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A. effectiveness of insulating material around the engine

B. condition of engine

C. working condition

D. properties of the medium/substance used

E. temperature range of operation
85. Which of the following processes is irreversible process___________________?
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A. isothermal

B. none of the above

C. adiabatic

D. throttling

E. all of the above

86. Measurement of temperature is based on_________________?
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A. joules law

B. thermodynamic properties

C. second law of thermodynamics

D. zeroth law of thermodynamics

E. first law of thermodynamics

87. In a Carnot cycle, heat is transferred at_______________________?
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A. constant temperature

B. constant enthaply

C. constant volume

D. constant pressure

E. any one of the above

88. A closed system is one in which_________________________?
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A. mass does not cross boundaries of the system, though energy may do so

B. mass crosses the boundary but not the energy

C. neither mass nor energy crosses the boundaries of the system

D. both energy and mass cross the boundaries of the system

E. thermodynamic reactions take place

89. A sudden fall in the barometer reading is a sign of approaching________________?
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A. cold wave

B. fine weather

C. storm

D. rains

E. hot wave

90. Addition of heat at constant pressure to a gas results in________________?
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A. doing external work

B. raising its temperature

C. raising its temperature and doing external work

D. raising its volume

E. raising its pressure

91. An ideal gas as compared to a real gas at very high pressure occupies_________________?
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A. same volume

B. no such correlation

C. more volume

D. unpredictable behaviour

E. less volume

92. If a gas is heated against a pressure, keeping the volume constant, then work done will be equal to__________________?
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A. ve

B. #NAME?

C. zero

D. pressure x volume

E. any where between zero and infinity

93. An adiabatic wall is one which__________________?
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A. discourages thermal interaction

B. prevents thermal interaction

C. permits thermal interaction

D. dos not exist.

E. encourages thermal interaction

94. A heat exchange process in which the product of pressure and volume remains constant is known as_______________?
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A. throttling process

B. isentropic process

C. hyperbolic process

D. heat exchange process

E. adiabatic process

95. The basis for measuring thermodynamic property of temperature is given by___________________?
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A. third law of thermodynamics

B. first law of thermodynamics

C. zeroth law of thermodynamics

D. second law of thermodynamics

E. Avogadros hypothesis

96. Kinetic energy of the molecules in terms of absolute temperature (T) is proportional to________________?
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A. 1/Vr

B. J2

C. T

D. j

E. Vr

97. If a gas vapour is allowed to expand through a very minute aperture, then such a process is known as__________________?
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A. parabolic expansion

B. throttling

C. free expansion

D. adiabatic expansion

E. hyperbolic expansion

98. Atmospheric pressure is equal to____________?
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A. 1.013 bar

B. All of these

C. 101.3KN/m2

D. 760mm of Hg

99. An open system is one in which____________________?
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A. mass does not cross boundaries of the system, though energy may do so

B. neither mass nor energy crosses the boundaries of the system

C. both energy and mass cross the boundaries of the system

D. mass crosses the boundary but not the energy

E. thermodynamic reactions do not occur

100. For which of the following substances, the internal energy and enthalpy are the functions of temperature only____________________?
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A. any gas

B. perfect gas

C. saturated steam

D. superheated steam

E. water