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.

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1.	A definite area or space where some thermodynamic process takes place is known as
A.	thermodynamic system
B.	thermodynamic cycle
C.	thermodynamic process
D.	thermodynamic law
Answer» A. thermodynamic system

2.	An open system is one in which
A.	heat & work cross the boundary of the system, but the mass of the working substance does not
B.	mass of working substance crosses the boundary of the system but the heat & work do not
C.	both the heat & work as well as mass of the working substance cross the boundary of the system
D.	neither the heat & work nor the mass of the working substances cross the boundary of the system
Answer» C. both the heat & work as well as mass of the working substance cross the boundary of the system

3.	An isolated system
A.	is a specified region where transfer of energy and/or mass take place
B.	is a region of constant mass & only energy is allowed to cross the boundaries
C.	cannot transfer either energy or mass to or from the surroundings
D.	is one in which mass within the system is not necessarily constant
Answer» C. cannot transfer either energy or mass to or from the surroundings

4.	Which of the following is an intensive property of a thermodynamic system
A.	volume
B.	temperature
C.	mass
D.	energy
Answer» B. temperature

5.	Which of the following is the extensive property of a thermodynamic system
A.	pressure
B.	volume
C.	temperature
D.	density
Answer» B. volume

6.	When two bodies are in thermal equilibrium with a third body they are also in thermal equilibrium with each other. This statement is called
A.	zeroth law of thermodynamics
B.	first law of thermodynamics
C.	second law of thermodynamics
D.	kelvin planck's law
Answer» A. zeroth law of thermodynamics

7.	The temperature at which the volume of a gas becomes zero is called
A.	absolute scale of temperature
B.	absolute zero temperature
C.	absolute temperature
D.	none of the above
Answer» B. absolute zero temperature

8.	The value of one bar (in SI units) is equal to
A.	100 n/m??
B.	1000 n/m??
C.	1??10⁴ n/m??
D.	1??10⁵ n/m??
Answer» D. 1??10⁵ n/m??

9.	The absolute zero pressure will be
A.	when molecular momentum of the systembecomes zero
B.	at sea level
C.	at the temperature of -273 k
D.	under vaccum conditions
Answer» A. when molecular momentum of the systembecomes zero

10.	Absolute zero temperature is taken as
A.	-273°c
B.	273°c
C.	237°c
D.	-373°c
Answer» A. -273°c

11.	Which of the following is correct?
A.	absolute pressure= guage pressure+ atmosphericpressure
B.	guage pressure= absolute pressure + atmosphericpressure
C.	atmospheric pressure= absolute pressure+ guagepressure
D.	absolute pressure= guage pressure-atmospheric pressure
Answer» A. absolute pressure= guage pressure+ atmosphericpressure

12.	The unit of energy in SI units is
A.	joule (j)
B.	joule metre (jm)
C.	watt (w)
D.	joule/metre (j/m)
Answer» A. joule (j)

13.	One watt is equal to
A.	1 nm/s
B.	1n/min
C.	10 n/s
D.	100 nm/s
Answer» A. 1 nm/s

14.	One joule (J) is equal to
A.	1 nm
B.	knm
C.	10 nm/s
D.	10 knm/s
Answer» A. 1 nm

17.	According to kinetic theory of heat
A.	temperature should rise during boiling
B.	temperature should fall during freezing
C.	at low temperature all bodies are in solid state
D.	at absolute zero there is absolutely no vibration ofmolecules
Answer» D. at absolute zero there is absolutely no vibration ofmolecules

15.	A series of operations, which take place in a certain order & restore the initial condition is known as
A.	reversible cycle
B.	irreversible cycle
C.	thermodynamic cycle
D.	none of the above
Answer» C. thermodynamic cycle

16.	The condition for the reversibility of a cycle is
A.	the pressure & temperature of the working substance must not differ, appreciably, from those of
B.	all the processes, taking place in the cycle of operation, must be extremely slow
C.	the working parts of the engine must be friction free
D.	all of the above
Answer» D. all of the above

18.	A system comprising a single phase is called a
A.	closed system
B.	open system
C.	isolated system
D.	homogeneous system
Answer» D. homogeneous system

19.	If all the variables of a stream are independent of time it is said to be in
A.	steady flow
B.	unsteady flow
C.	uniform flow
D.	closed flow
Answer» A. steady flow

20.	A control volume refers to
A.	a fixed region in space
B.	a specified mass
C.	an isolated system
D.	a reversible process only
Answer» A. a fixed region in space

21.	Internal energy of a perfect gas depends on
A.	temperature, specificheats & pressure
B.	temperature, specificheats & enthalpy
C.	temperature, specific heats& entropy
D.	temperature only
Answer» D. temperature only

22.	Steady flow process requires that
A.	conditions do not change with time at any point
B.	conditions are the same at adjacent points at anyinstant
C.	conditions change steadily with the time
D.	is constant
Answer» A. conditions do not change with time at any point

23.	The first law of thermodynamics for steady flow
A.	accounts for all energy entering & leaving a controlvolume
B.	is an energy balance for a specified mass of fluid
C.	is an expression of the conservation of linearmomentum
D.	is primarily concerned with heat transfer
Answer» A. accounts for all energy entering & leaving a controlvolume

24.	Which of the following is not a property of the system
A.	temperature
B.	pressure
C.	specific volume
D.	heat
Answer» D. heat

25.	The process or systems that do not involve heat are called
A.	isothermal processes
B.	equilibrium processes
C.	adiabatic processes
D.	steady processes
Answer» C. adiabatic processes

500+ Engineering Thermodynamics Solved MCQs

A definite area or space where some thermodynamic process takes place is known as

An open system is one in which

An isolated system

Which of the following is an intensive property of a thermodynamic system

Which of the following is the extensive property of a thermodynamic system

When two bodies are in thermal equilibrium with a third body they are also in thermal equilibrium with each other. This statement is called

The temperature at which the volume of a gas becomes zero is called

The value of one bar (in SI units) is equal to

The absolute zero pressure will be

Absolute zero temperature is taken as

Which of the following is correct?

The unit of energy in SI units is

One watt is equal to

One joule (J) is equal to

A series of operations, which take place in a certain order & restore the initial condition is known as

The condition for the reversibility of a cycle is

According to kinetic theory of heat

A system comprising a single phase is called a

If all the variables of a stream are independent of time it is said to be in

A control volume refers to

Internal energy of a perfect gas depends on

Steady flow process requires that

The first law of thermodynamics for steady flow

Which of the following is not a property of the system

The process or systems that do not involve heat are called

Which one of the following statements is correct?

First law of thermodynamics deals with conservation of

Which one of the following processes or systems does not involve heat

Thermodynamic equillibrium is completely defined by the specification of

………. Is not a property of the system

In which of the following processes the external work done is not zero?

The extension & compression of a helical spring is an example of

In all irrevesible processes, the entropy of the system

Temperature of a gas is produced due to which of the following?

The same volume of all gases at same temperatureand pressure would represent their

First law of thermodynamics gives relationship between which of the following?

The temperature in a process in which work is done by expanding a gas under adiabatic condition will

On which of the following laws measurement of temperature is based?

The perpetual motion of the first kind is represented by which of the following?

Which of the following statements regarding a perpetual motion machine is correct?

Which of the following statements, regarding a property of system, is correct?

……….. Is an intensive property

A system is said to be in thermodynamic equilibrium if it is in

The basis for measuring thermodynamic property of temperature is given by ……. Law of thermodynamics

As differentials, heat & work would be described mathematically as

Which of the following is an open thermodynamic system?

……… is a non-quasistatic process

Choose the correct statement

The first law of thermodynamics defines

A process becomes irreversible due to

The main cause of the irreversibility is

An isentropic process is always

In the polytropic process equation pvⁿ = constant, if n is infinitely large, the process is termed as

Second law of thermodynamics defines

For a reversible adiabatic process, the change in entropy is

For any reversible process, the change in entropy of the system & surroundings is

For any irreversible process the net entropy change is

The processes of a Carnot cycle are

Isentropic flow is

In a carnot engine, when the working substance gives heat to the sink

If the temperature of the source is increased, the efficiency of the Carnot engine

The efficiency of an ideal Carnot engine depends on

In a reversible cycle, the entropy of the system

Kelvin-Plank's law deals with

Which of the following statements is correct according to Clausius statement of second law of thermodynamics?

The property of a working substance which increases or decreases as the heat is supplied or removed in a reversible manner is known as

The entropy may be expressed as a function of

The change of entropy when heat is absorbed by the gas is

Which of the following statements is correct?

In an irreversible process, there is a

The efficiency of the Carnot cycle may be increased by

Which of the following is the correct statement?

The reversible engines are

Gases could have an infinite number of specific heats but only ……. Specific heats are defined

The area under the T-s (temperature - entropy) curve of any thermodynamic process represents

Second law of thermodynamics defines

For storing a gas which one of the following types of compression will be ideal

A process which can be stopped at any stage & reversed so that the system & the surroundings are exactly restored to their initial states is known as

Which of the following is a reversible process?

Consider the following statements: The definition of
1. temperature is due to zeroth law of thermodynamics
2. entropy is due to first law of thermodynamics
3. internal energy is due to second law of thermodynamics
4. reversibility is due to Kelvin-Planck's ststement of these statements

26.	Which one of the following statements is correct?
A.	pressure is an extensiveproperty
B.	density is an intensiveproperty
C.	density is an extensiveproperty
D.	temperature is anextensive property
Answer» B. density is an intensiveproperty

27.	First law of thermodynamics deals with conservation of
A.	mass
B.	momentum
C.	energy
D.	heat
Answer» C. energy

29.	Thermodynamic equillibrium is completely defined by the specification of
A.	generalised displacements
B.	internal energy
C.	enthalpy
D.	all of the above
Answer» D. all of the above

31.	In which of the following processes the external work done is not zero?
A.	throttling
B.	free expansion
C.	constant volume process
D.	constant pressureprocess
Answer» D. constant pressureprocess

32.	The extension & compression of a helical spring is an example of
A.	irreversible process
B.	reversible process
C.	isothermal process
D.	adiabatic process
Answer» B. reversible process

33.	In all irrevesible processes, the entropy of the system
A.	remains unaltered
B.	reduces to zero
C.	increases
D.	none of the above
Answer» C. increases

34.	Temperature of a gas is produced due to which of the following?
A.	attraction of molecules
B.	repulsion of molecules
C.	kinetic energy of molecules
D.	all of the above
Answer» C. kinetic energy of molecules

35.	The same volume of all gases at same temperatureand pressure would represent their
A.	specific gravity
B.	densities
C.	specific weights
D.	molecular weights
Answer» D. molecular weights

36.	First law of thermodynamics gives relationship between which of the following?
A.	heat & internal energy
B.	heat & work
C.	heat, work & properties of the system
D.	various thermodynamics processes
Answer» C. heat, work & properties of the system

37.	The temperature in a process in which work is done by expanding a gas under adiabatic condition will
A.	decrease
B.	increase
C.	first decrease & then increase
D.	remain unaltered
Answer» A. decrease