101. Addition of heat at constant pressure to a gas results in

(a) raising its temperature
(b) raising its pressure
(c) raising its volume
(d) raising its temperature and doing external work
(e) doing external work

Ans: d

102. Carnot cycle has maximum efficiency for

(a) reversible engine
(b) irreversible engine
(c) new engine
(d) petrol engine
(e) diesel engine

Ans: a

103. Measurement of temperature is based on

(a) thermodynamic properties
(b) zeroth law of thermodynamics
(c) first law of thermodynamics
(d) second law of thermodynamics
(e) joule’s law

Ans: b

104. Carnot cycle efficiency depends upon

(a) properties of the medium/substance used
(b) condition of engine
(c) working condition
(d) temperature range of operation
(e) effectiveness of insulating material around the engine

Ans: d

105. Carnot cycle efficiency is maximum when

(a) initial temperature is 0°K
(b) final temperature is 0°K
(c) difference between initial and final temperature is 0°K
(d) final temperature is 0°C
(e) initial temperature is minimum possible

Ans: b

106. An engine operates between temperatures of 900°Kandr2 and another engine between T2 and 400°K For both to do equal work, value of T2 will be

(a) 650°K
(b) 600°K
(c) 625°K
(d) 700°K
(e) 750°K

Ans: a

107. If heat be exchanged in a reversible manner, which of the following property of the working substance will change accordingly

(a) temperature
(b) enthalpy
(c) internal energy
(d) entropy
(e) all of the above

Ans: d

108. If a system after undergoing a series of processes, returns to the initial state then

(a) process is thermodynamically in equilibrium
(b) process is executed in closed system cycle
(c) its entropy will change due to irreversibility
(d) sum of heat and work transfer will be zero
(e) no work will be done by the system

Ans: d

109. Which of the following represents the perpetual motion of the first kind

(a) engine with 100% thermal efficiency
(b) a fully reversible engine
(c) transfer of heat energy from low temperature source to high temperature source
(d) a machine that continuously creates its own energy
(e) production of energy by temperature differential in sea water at different levels

Ans: c

110. An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is

(a) feasible
(b) impossible
(c) possible
(d) possible, but with lot of sophistication
(e) desirable

Ans: d

112. A manufacturer claims to have a heat engine capable of developing 20 h.p. by receiving heat input of 400 kcal/mt and working between the temperature limits of 227° C and 27° C. His claim is

(a) justified
(b) not possible
(c) may be possible with lot of sophistica-tions
(d) cost will be very high
(e) theroretically possible

Ans: b

113. In a Carnot cycle, heat is transferred at

(a) constant pressure
(b) constant volume
(c) constant temperature
(d) constant enthalpy
(e) any one of the above

Ans: c

114. A diathermy wall is one which

(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) does not exist

Ans: b

115. An adiabatic wall is one which

(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) dos not exist

Ans: a

116. The door of a running refrigerator inside a room was left open. Which of the following statements is correct?

(a) The room will be cooled to the temperature inside the refrigerator.
(b) The room will be cooled very slightly.
(c) The room will be gradually warmed up.
(d) The temperature of the air in room will remain unaffected.
(e) any one of above is possible depending on the capacity.

Ans: c

117. Compressed air coming out from a punctured football

(a) becomes hotter
(b) becomes cooler
(c) remains at the same temperature
(d) may become hotter or cooler depending upon the humidity of the surround¬ing air
(e) attains atmospheric temperature

Ans: b

118. Water contained in a beaker can be made to boil by passing steam through it

(a) at atmospheric pressure
(b) at a pressure below the tropospheric pressure
(c) at a pressure greater than atmospheric pressure
(d) any pressure
(e) not possible

Ans: c

119. During throttling process

(a) heat exchange does not take place
(b) no work is done by expanding steam
(c) there is no change of internal energy of steam
(d) all of the above
(e) entropy decreases

Ans: d

120. The energy of molecular motion appears as

(a) heat
(b) potential energy
(c) surface tension
(d) friction
(e) increase in pressure

Ans: a

121. A sudden fall in the barometer reading is a sign of approaching

(a) fine weather
(b) rains
(c) storm
(d) cold wave
(e) hot wave

Ans: c

122. The unit of universal gas constant is

(a) watts/°K
(b) dynes/°C
(c) ergscm/°K
(d) erg/°K
(e) none of the above

Ans: d

123. Calorie is a measure of

(a) specific heat
(b) quantity of heat
(c) thermal capacity
(d)entropy
(e) work

Ans: b

124. 1 kgf/cm2 is equal to

(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) l00mmHg.

Ans: c

125. Barometric pressure is equal to

(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) 100mm Hg

Ans: a