500+ Engineering Thermodynamics Solved MCQs

Engineering thermodynamics is a branch of engineering that deals with the study of energy, heat, and their relationship to work and the transfer of energy from one place to another.

It is a fundamental subject that forms the basis of many other branches of engineering, including mechanical, chemical, and electrical engineering. The principles of thermodynamics are used to design engines, power plants, refrigeration systems, and a wide variety of other devices and systems that are essential to modern society. Some of the key concepts in engineering thermodynamics include the laws of thermodynamics, entropy, and the concept of equilibrium.

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .

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101.	The amount of heat absorbed by a system at lower temperature is
A.	coeff. of performance
B.	efficiency
C.	work supplied
D.	refrigerating effect
Answer» C. work supplied

102.	Tds equation is
A.	a) tds=cvdt + t
B.	..
Answer» A. a) tds=cvdt + t

103.	In an ideal gas the partial pressure of a component is
A.	inversely proportional to the square of the molefraction
B.	directly proportional to the mole fraction
C.	inversely proportional to the mole fraction
D.	equal to the mole fraction
Answer» B. directly proportional to the mole fraction

104.	The value of the univesal gas constant is
A.	0.314 j/kg k
B.	83.14 kj/kg k
C.	848 kj/kg k
D.	8.314 kj/kg k
Answer» D. 8.314 kj/kg k

105.	Choose the correct answer
A.	a perfect gas does not obey the law pv=rt
B.	a perfect gas obeys the law pv=rt & has constant specific heat
C.	a perfect gas obeys the law pv=rt but have variable specific heat capacities
D.	all of the above
Answer» B. a perfect gas obeys the law pv=rt & has constant specific heat

106.	Boyle's law states that, when tempearture is constant, the volume of a given mass of a perfect gas
A.	varies directly as the absolute pressure
B.	varies inversely as the absolute pressure
C.	varies as square of the absolute pressue
D.	does not vary with the absolute pressure
Answer» B. varies inversely as the absolute pressure

107.	Charle's law states that if any gas is heated at constant pressure, its volume
A.	changes directly as it absolute temperature
B.	changes inversely as its absolute temperature
C.	changes as square of the absolute temperature
D.	does not change with absolute temperature
Answer» A. changes directly as it absolute temperature

108.	The equation of state of an ideal gas is a relationship between the variables:
A.	pressure & volume
B.	pressure & temperature
C.	pressure, volume & temperature
D.	none of the above
Answer» C. pressure, volume & temperature

109.	Joule's law states that the specific internal energy of a gas depends only on
A.	the pressure of the gas
B.	the volume of the gas
C.	the temperature of the gas
D.	none of the above
Answer» C. the temperature of the gas

110.	………. Law states that equal volume of all gases, at the same temperature & pressure, contains equal number of molecules
A.	boyle's
B.	gay-lussac
C.	avogadro
D.	charle's
Answer» C. avogadro

111.	The change of entropy is considered to be ……… when heat is absorbed by the gas
A.	positive
B.	negative
C.	zero
D.	none of the above
Answer» A. positive

112.	………. Is one in which neither any heat enters nor leaves the system
A.	isochoric process
B.	isobaric process
C.	isentropic process
D.	isothermal process
Answer» C. isentropic process

113.	Entropy of the universe
A.	tends to zero
B.	tends to a minimum
C.	tends to a maximum
D.	none of the above
Answer» C. tends to a maximum

114.	A gas can never be liquid
A.	above criticaltemperature
B.	when it is diatomic
C.	when it is impure
D.	above roomtemperature
Answer» A. above criticaltemperature

118.	In a Carnot cycle which of the following processez must be carried out at extremely slow speed?
A.	isothermal compression
B.	adiabatic expansion
C.	adiabatic compression
D.	none of the above
Answer» A. isothermal compression

115.	Which of the following remains constant during an adiabatic expansion
A.	entropy
B.	temperature
C.	internal energy
D.	none of the above
Answer» A. entropy

116.	In which of the following processes the change in internal energy of a gas is equal to the work done
A.	adiabatic process
B.	isothermal process
C.	constant volume process
D.	constant pressure process
Answer» A. adiabatic process

117.	The specific heat of a gas is a function of
A.	temperature only
B.	temperature & pressure
C.	temperature & entropy
D.	temperature, pressure& entropy
Answer» A. temperature only

119.	In the case of real gases, cp will be equal to cv
A.	at absolute zero
B.	at triple point
C.	at critical temperature
D.	above criticaltempeature
Answer» A. at absolute zero

120.	The physical properties of a perfect gas are controlled by which of the following variables?
A.	volume
B.	temperature
C.	pressure
D.	all of the above
Answer» D. all of the above

121.	Universal gas constant is defined as equal to the product of the molecular weight of the gas &
A.	gas constant
B.	specific heat at constant volume
C.	specific heat a constant pressure
D.	ratio of two specific heats
Answer» A. gas constant

122.	All engineering process, strictly speaking are
A.	reversible cycle
B.	irreversible
C.	quasti-static
D.	thermodynamically inequillibrium
Answer» D. thermodynamically inequillibrium

123.	Isothermal, isobaric, isochoric & adiabatic processes, under ideal conditions, are …. Processes
A.	thermodynamic
B.	stable
C.	dynamic
D.	quasi-static
Answer» D. quasi-static

124.	Change of entropy depends upon which of the following?
A.	change of heat
B.	change of specific heats
C.	change of pressure &volume
D.	none of the above
Answer» A. change of heat

125.	In a reversible adiabatic process head added is equal to
A.	zero
B.	positive value
Answer» A. zero

500+ Engineering Thermodynamics Solved MCQs

The amount of heat absorbed by a system at lower temperature is

Tds equation is

In an ideal gas the partial pressure of a component is

The value of the univesal gas constant is

Choose the correct answer

Boyle's law states that, when tempearture is constant, the volume of a given mass of a perfect gas

Charle's law states that if any gas is heated at constant pressure, its volume

The equation of state of an ideal gas is a relationship between the variables:

Joule's law states that the specific internal energy of a gas depends only on

………. Law states that equal volume of all gases, at the same temperature & pressure, contains equal number of molecules

The change of entropy is considered to be ……… when heat is absorbed by the gas

………. Is one in which neither any heat enters nor leaves the system

Entropy of the universe

A gas can never be liquid

Which of the following remains constant during an adiabatic expansion

In which of the following processes the change in internal energy of a gas is equal to the work done

The specific heat of a gas is a function of

In a Carnot cycle which of the following processez must be carried out at extremely slow speed?

In the case of real gases, cp will be equal to cv

The physical properties of a perfect gas are controlled by which of the following variables?

Universal gas constant is defined as equal to the product of the molecular weight of the gas &

All engineering process, strictly speaking are

Isothermal, isobaric, isochoric & adiabatic processes, under ideal conditions, are …. Processes

Change of entropy depends upon which of the following?

In a reversible adiabatic process head added is equal to

During a throttling process

Under which of the following conditions all gases behave ideally?

……….. Is the unit of entropy

Internal energy & enthalpy of an ideal gas are functions of

When two gases suddenly mix up with each other then resultant entropy of the system will

On which of the following factors does air standard efficiency of a diesel cycle depend?

Regarding enthalpy which of the following statements is incorrect?

Which of the following processes is reversible process?

Which of the following processes are reversible processes?

For ……. The internal energy & enthalpy are the functions of temperature only

The index of compression n tends to reach ?(ratio of specific heats)

In the reversible polytropic process the value of exponent n varies between

An ideal gas as compared to a real gas at very high pressure occupies

Adiabatic & isothermal processes are identical at

In polytropic process pv?=C the value of exponent n=±? is indicative of

Entropy in statistical thermodynamics is defined as

A mixture of gases expands from 0.03 m³ to 0.06 m³ at a constant pressure of 1 Mpa & absorbs 84 kJ of heat during the process. The change in internal energy of the mixture is

Increase in entropy of a system represents

Which one of the following pairs best expresses a relationship similar to that expressed in the pair 'pressure-volume' for a thermodynamic system undergoing a process?

Variations of pressure & volume at constant temperature are correlated through

The relationship between pressure & volume is expressed as pv?=const. Select wrong statement

A gas expands from initial condition of (p1, v1, T1) to final condition (p2, v1, T2), then according to Charle's law:

Air expands from initial condition of p1, v1 to final condition of 1/2 p1, 2v1. Choose the correct statement

Air with initial condition of p1, v1 expands to final condition of p1/2, 3v1. The process is

The internal energy of a perfect gas is a function of

126.	During a throttling process
A.	exchange of heat doesnot take place
B.	expandingsteam does nowork
C.	internal energy of steamdoes not change
D.	all of the above
Answer» D. all of the above

127.	Under which of the following conditions all gases behave ideally?
A.	high pressure conditions
B.	law pressure conditions
C.	vaccum conditions
D.	all of the aboveconditions
Answer» B. law pressure conditions

128.	……….. Is the unit of entropy
A.	j/kg
B.	j/kg k
C.	j/k
D.	j/kgs
Answer» B. j/kg k

129.	Internal energy & enthalpy of an ideal gas are functions of
A.	pressure only
B.	temperature only
C.	specific volume only
D.	temperature & pressure
Answer» B. temperature only

130.	When two gases suddenly mix up with each other then resultant entropy of the system will
A.	remain unaltered
B.	decrease
C.	increase
D.	becomes zero
Answer» C. increase

131.	On which of the following factors does air standard efficiency of a diesel cycle depend?
A.	adiabatic compression ratio
B.	ratio of specific heats
C.	cut-off ratio
D.	all of the above
Answer» D. all of the above

132.	Regarding enthalpy which of the following statements is incorrect?
A.	it is the function of specific heat at constantvolume
B.	it is the extensive property of the system
C.	it is the sum of internal energy & the pressurevolume product
D.	it is the same as heat transfer during constantpressure process
Answer» A. it is the function of specific heat at constantvolume

133.	Which of the following processes is reversible process?
A.	throttling
B.	adiabatic
C.	isothermal
D.	none of the above
Answer» A. throttling

134.	Which of the following processes are reversible processes?
A.	isothermal & adiabatic
B.	constant volume &constant pressure
C.	hyperbolic & pv?= constant
D.	none of the above
Answer» A. isothermal & adiabatic

135.	For ……. The internal energy & enthalpy are the functions of temperature only
A.	perfect gas
B.	water in pipes surrounded by steam
C.	saturated steam
D.	superheated steam
Answer» A. perfect gas