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Thermodynamics MCQs | Thermodynamics Short Questions and Answers

41 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
Answer: all of the above
42 The unit’of universal gas constant is
[A] watts/°K
[B] dynes/°C
[C] ergscm/°K
[D] erg/°K
Answer: erg/°K

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43 I kgf/cm2 is equal to
[A] 760 mm Hg
[B] zero mm Hg
[C] 735.6 mm Hg
[D] 1 mm Hg
Answer: 735.6 mm Hg
44 A perpetual motion machine is
[A] a thermodynamic machine
[B] a non-thermodynamic machine
[C] a hypothetical machine
[D] a hypothetical machine whose opera-tion would violate the laws of thermodynamics
Answer: a hypothetical machine whose opera-tion would violate the laws of thermodynamics
45 Thermal power plant works on
[A] Carnot cycle
[B] Joule cycle
[C] Rankine cycle
[D] Otto cycle
Answer: Rankine cycle
46 The efficiency of a Carnot engine depends on
[A] working substance
[B] design of engine
[C] size of engine
[D] temperatures of source and sink
Answer: temperatures of source and sink
47 Stirling and Ericsson cycles are
[A] reversible cycles
[B] irreversible cycles
[C] quasi-static cycles
[D] semi-reversible cycles
Answer: reversible cycles
48 Which of the following cycles is not a reversible cycle
[A] Carnot
[B] Ericsson
[C] Stirling
[D] none of the above
Answer: more volume
49 The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will
[A] increase
[B] decrease
[C] remain unchanged
[D] increase/decrease depending on ap-plication
Answer: decrease
50 If value of n is infinitely large in a polytropic process pV” = C, then the process is known as constant
[A] volume
[B] pressure
[C] temperature
[D] enthalpy
Answer: volume
51 The index of compression n tends to reach ratio of specific heats y when
[A] flow is uniform and steady
[B] process is isentropic
[C] process is isothermal
[D] process is isentropic and specific heat does not change with temperature
Answer: process is isentropic and specific heat does not change with temperature
52 Change in enthalpy of a system is the heat supplied at
[A] constant pressure
[B] constant temperature
[C] constant volume
[D] constant entropy
Answer: constant pressure
53 The term N.T.P. stands for
[A] nominal temperature and pressure
[B] natural temperature and pressure
[C] normal temperature and pressure
[D] normal thermodynamic practice
Answer: normal temperature and pressure
54 A heat exchange process in which the product of pressure and volume remains constant is known as
[A] heat exchange process
[B] throttling process
[C] isentropic process
[D] hyperbolic process
Answer: hyperbolic process
55 In an isothermal process, the internal energy of gas molecules
[A] increases
[B] decreases
[C] remains constant
[D] may increase/decrease depending on the properties of gas
Answer: remains constant
56 The basis for measuring thermodynamic property of temperature is given by
[A] zeroth law of thermodynamics
[B] first law of thermodynamics
[C] second law of thermodynamics
[D] third law of thermodynamics
Answer: zeroth law of thermodynamics
57 Work done is zero for the following process
[A] constant volume
[B] free expansion
[C] throttling
[D] all Of the above
Answer: all Of the above
58 For which of the following substances, the gas laws can be used with minimum error
[A] dry steam
[B] wet steam
[C] saturated steam
[D] superheated steam
Answer: superheated steam
59 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
[A] 100 xlOO5 joules
[B] lxlO5 joules
[C] 10 xlO5 joules
[D] 10 xlO5 kilo joules
Answer: 10 xlO5 joules
60 The value of the product of molecular weight and the gas characteristic constant for all the gases in M.K.S. unit is
[A] 29.27 kgfm/mol°K
[B] 8314kgfm/mol°K
[C] 848kgfm/mol°K
[D] 427kgfm/mol°K
Answer: 848kgfm/mol°K

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