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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 .

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
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
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
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
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
28.

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

A. steady processes
B. isothermal processes
C. adiabatic processes
D. thermal processes
Answer» C. adiabatic processes
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
30.

………. Is not a property of the system

A. pressure
B. temperature
C. heat
D. specific volume
Answer» C. heat
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
38.

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

A. joule's law
B. zeroth law of thermodynamics
C. first law of thermodynamics
D. second law of thermodynamics
Answer» B. zeroth law of thermodynamics
39.

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

A. a machine that continuously creates itsown energy
B. an engine with 100 percent efficiency
C. a fully reversible engine
D. none of the above
Answer» A. a machine that continuously creates itsown energy
40.

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

A. it is an in efficient machine
B. it is non-thermodynamic machine
C. it is thermodynamic machine
D. it is hypothetic machine whose operation would violate the laws of thermodynamics
Answer» D. it is hypothetic machine whose operation would violate the laws of thermodynamics
41.

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

A. it is path function
B. it is a point function
C. it is always of intensive type
D. none of the above
Answer» B. it is a point function
42.

……….. Is an intensive property

A. specific volume
B. total volume
C. total mass
D. total energy of a system
Answer» A. specific volume
43.

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

A. chemical equilibrium
B. thermal equilibrium
C. mechanical equilibrium
D. all of the above
Answer» D. all of the above
44.

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

A. zeroth
B. first
C. second
D. third
Answer» A. zeroth
45.

As differentials, heat & work would be described mathematically as

A. exact
B. inexact
C. point function
D. discontinuity
Answer» B. inexact
46.

Which of the following is an open thermodynamic system?

A. pressure cooker
B. manual ice cream freezer
C. centrifugal pump
D. none of the above
Answer» C. centrifugal pump
47.

……… is a non-quasistatic process

A. free expansion of gas
B. expansion of gas in a cylinder under constantpressure
C. rapid leakage of air from a bicycle tyre
D. gradual compression of gas inside a piston-cylinderarrangement
Answer» A. free expansion of gas
48.

Choose the correct statement

A. pressure, temp. &entropy are extensive properties
B. pressure, temp. &entropy are intensive properties
C. pressure, volume & temp. are extensive properties
D. volume & entropy are extensive properties
Answer» D. volume & entropy are extensive properties
49.

The first law of thermodynamics defines

A. entropy
B. internal energy
C. work
D. heat
Answer» B. internal energy
50.

A process becomes irreversible due to

A. work performed by thesystem
B. work performed uponthe system
C. heat supplied to the system
D. friction in the system
Answer» D. friction in the system

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