# Laws of Thermodynamics MCQs with Answers

Laws of Thermodynamics MCQs are very important test and often asked by various testing services and competitive exams around the world. Here you will find all the Important Laws of Thermodynamics MCQs for Preparation.

The student can clear their concepts for Laws of Thermodynamics online quiz by attempting it. Doing MCQs based Laws of Thermodynamics will help you to check your understanding and identify areas of improvement.

## Laws of Thermodynamics Online MCQs with Answers

Which of the following is a statement of the first law of thermodynamics?
a) Energy cannot be created or destroyed, only transferred or transformed
b) The entropy of a system tends to increase over time
c) The efficiency of a heat engine is always less than 100%
d) Heat flows from a higher temperature to a lower temperature

a) Energy cannot be created or destroyed, only transferred or transformed

The second law of thermodynamics states that:
a) Energy cannot be created or destroyed, only transferred or transformed
b) The entropy of a system tends to increase over time
c) The efficiency of a heat engine is always less than 100%
d) Heat flows from a higher temperature to a lower temperature

b) The entropy of a system tends to increase over time

The third law of thermodynamics states that:
a) Energy cannot be created or destroyed, only transferred or transformed
b) The entropy of a system tends to increase over time
c) The efficiency of a heat engine is always less than 100%
d) It is impossible to reach absolute zero temperature

d) It is impossible to reach absolute zero temperature

The first law of thermodynamics is a statement of:
a) Conservation of energy
b) Conservation of mass
c) Conservation of momentum
d) Conservation of entropy

a) Conservation of energy

The second law of thermodynamics is a statement of:
a) Conservation of energy
b) Conservation of mass
c) Conservation of momentum
d) Increase of entropy

d) Increase of entropy

The third law of thermodynamics is a statement about the behavior of systems at:
a) High temperatures
b) Low temperatures
c) Equilibrium
d) Critical points

b) Low temperatures

The efficiency of a heat engine is defined as:
a) The ratio of work output to heat input
b) The ratio of heat output to heat input
c) The ratio of heat input to work output
d) The ratio of work input to heat output

a) The ratio of work output to heat input

The efficiency of a Carnot heat engine depends on:
a) The temperature of the heat source
b) The temperature of the heat sink
c) Both the temperature of the heat source and the heat sink
d) Neither the temperature of the heat source nor the heat sink

c) Both the temperature of the heat source and the heat sink

The efficiency of a Carnot heat engine operating between two temperatures T1 and T2 is given by:
a) η = (T1 – T2) / T1
b) η = (T1 – T2) / T2
c) η = T2 / (T1 – T2)
d) η = T1 / (T1 – T2)

b) η = (T1 – T2) / T1

The Carnot cycle is a theoretical cycle that represents:
a) The most efficient heat engine possible
b) The least efficient heat engine possible
c) An ideal gas undergoing an isothermal process

a) The most efficient heat engine possible

The Clausius statement of the second law of thermodynamics states that:
a) It is impossible to construct a heat engine that operates in a continuous cycle and produces no net work
b) Heat cannot flow spontaneously from a colder body to a hotter body
c) The entropy of a closed system tends to increase over time
d) It is impossible to reach absolute zero temperature

b) Heat cannot flow spontaneously from a colder body to a hotter body

The Kelvin-Planck statement of the second law of thermodynamics states that:
a) It is impossible to construct a heat engine that operates in a continuous cycle and produces no net work
b) Heat cannot flow spontaneously from a colder body to a hotter body
c) The entropy of a closed system tends to increase over time
d) It is impossible to reach absolute zero temperature

a) It is impossible to construct a heat engine that operates in a continuous cycle and produces no net work

Entropy is a measure of:
a) The disorder or randomness of a system
b) The temperature of a system
c) The energy of a system
d) The pressure of a system

a) The disorder or randomness of a system

The entropy change of a system undergoing a reversible process is given by:
a) ΔS = Q / T
b) ΔS = Q * T
c) ΔS = T / Q
d) ΔS = T * Q

a) ΔS = Q / T

The entropy of a perfectly ordered crystal at absolute zero temperature is:
a) Zero
b) Infinite
c) Positive
d) Negative

a) Zero

The entropy of a closed system tends to increase over time according to:
a) The first law of thermodynamics
b) The second law of thermodynamics
c) The third law of thermodynamics
d) The zeroth law of thermodynamics

b) The second law of thermodynamics

The process of heat transfer that occurs spontaneously and naturally is:
a) Conduction
b) Convection
d) None of the above

The reversible process is an idealized process that is:
a) Quasistatic and always in thermal equilibrium with its surroundings
b) Spontaneous and irreversible
c) Fast and efficient
d) None of the above

a) Quasistatic and always in thermal equilibrium with its surroundings

The irreversible process is a process that:
a) Occurs slowly and efficiently
b) Can be reversed without any changes
c) Results in an increase in entropy
d) Does not involve energy transfer

c) Results in an increase in entropy

The absolute zero temperature is:
a) The lowest possible temperature in the universe
b) The temperature at which all molecular motion ceases
c) -273.15°C
d) All of the above

d) All of the above

The heat death of the universe refers to:
a) The end of all heat transfer in the universe
b) The end of all energy in the universe
c) The end of all life in the universe
d) The end of all matter in the universe

a) The end of all heat transfer in the universe

The principle of conservation of energy is closely related to the:
a) First law of thermodynamics
b) Second law of thermodynamics
c) Third law of thermodynamics
d) Zeroth law of thermodynamics

a) First law of thermodynamics

The efficiency of a real heat engine is always:
a) Less than 100%
b) Equal to 100%
c) Greater than 100%
d) Variable depending on the operating conditions

a) Less than 100%

The entropy change of the universe is always:
a) Positive
b) Negative
c) Zero
d) Variable depending on the process

a) Positive

The concept of temperature is related to the:
a) Zeroth law of thermodynamics
b) First law of thermodynamics
c) Second law of thermodynamics
d) Third law of thermodynamics

a) Zeroth law of thermodynamics

The concept of entropy was introduced by:
a) Rudolf Clausius
b) Lord Kelvin
c) James Joule
d) Max Planck

a) Rudolf Clausius

The concept of enthalpy is related to the:
a) Heat transfer at constant volume
b) Heat transfer at constant pressure
c) Heat transfer at constant temperature
d) Heat transfer in a reversible process

b) Heat transfer at constant pressure

The change in internal energy of a system is given by:
a) ΔU = Q + W
b) ΔU = Q – W
c) ΔU = Q * W
d) ΔU = Q / W

b) ΔU = Q – W

The concept of heat capacity is related to the:
a) Amount of heat required to raise the temperature of a substance
b) Amount of heat required to change the phase of a substance
c) Amount of heat transferred in a reversible process
d) Amount of heat transferred at constant pressure

a) Amount of heat required to raise the temperature of a substance

The concept of work is related to the:
a) Transfer of energy by heat
b) Transfer of energy by radiation
c) Transfer of energy by conduction
d) Transfer of energy by mechanical means

d) Transfer of energy by mechanical means

The Carnot efficiency of a heat engine operating between two temperatures T1 and T2 is given by:
a) η = (T1 – T2) / T1
b) η = (T1 – T2) / T2
c) η = T2 / (T1 – T2)
d) η = T1 / (T1 – T2)

b) η = (T1 – T2) / T1

The concept of entropy can be applied to:
a) Closed systems
b) Open systems
c) Isolated systems
d) All of the above

d) All of the above

The change in entropy of a system is given by:
a) ΔS = Q / T
b) ΔS = Q * T
c) ΔS = T / Q
d) ΔS = T * Q

a) ΔS = Q / T

The concept of heat transfer is related to the:
a) Transfer of energy by radiation
b) Transfer of energy by conduction
c) Transfer of energy by convection
d) All of the above

d) All of the above

The concept of equilibrium is related to the:
a) Zeroth law of thermodynamics
b) First law of thermodynamics
c) Second law of thermodynamics
d) Third law of thermodynamics

a) Zeroth law of thermodynamics

The principle of conservation of energy is also known as:
a) Kelvin-Planck statement
b) Clausius statement
c) Joule’s law
d) Ohm’s law

c) Joule’s law

The concept of reversibility is closely related to:
a) Carnot cycle
b) Entropy change
c) Heat transfer
d) Enthalpy change

a) Carnot cycle

The concept of adiabatic process is related to the:
a) Transfer of energy by heat
b) Transfer of energy by radiation
c) Transfer of energy by conduction
d) Process without any heat transfer

d) Process without any heat transfer

The concept of temperature is based on the behavior of:
a) Ideal gases
b) Real gases
c) Solids
d) Liquids

a) Ideal gases

The concept of internal energy is related to the:
a) Kinetic energy of molecules
b) Potential energy of molecules
c) Sum of kinetic and potential energy of molecules
d) None of the above

c) Sum of kinetic and potential energy of molecules

The concept of work is defined as:
a) The transfer of energy by heat
b) The transfer of energy by radiation
c) The transfer of energy by conduction
d) The transfer of energy by mechanical means

d) The transfer of energy by mechanical means

The concept of heat capacity is defined as:
a) The amount of heat required to raise the temperature of a substance
b) The amount of heat required to change the phase of a substance
c) The amount of heat transferred in a reversible process
d) The amount of heat transferred at constant pressure

a) The amount of heat required to raise the temperature of a substance

The concept of entropy is closely related to the:
a) Disorder or randomness of a system
b) Temperature of a system
c) Energy of a system
d) Pressure of a system

a) Disorder or randomness of a system

The concept of enthalpy is defined as:
a) The heat transfer at constant volume
b) The heat transfer at constant pressure
c) The heat transfer at constant temperature
d) The heat transfer in a reversible process

b) The heat transfer at constant pressure

The concept of work is given by:
a) W = P * V
b) W = ΔQ / ΔT
c) W = ΔU + PΔV
d) W = m * c * ΔT

c) W = ΔU + PΔV

The concept of heat is given by:
a) Q = P * V
b) Q = ΔQ / ΔT
c) Q = ΔU + PΔV
d) Q = m * c * ΔT

b) Q = ΔQ / ΔT

The concept of specific heat capacity is defined as:
a) The amount of heat required to raise the temperature of a substance by one degree
b) The amount of heat required to change the phase of a substance without a change in temperature
c) The heat required to raise the temperature of a unit mass of a substance by one degree
d) The heat required to change the phase of a unit mass of a substance without a change in temperature

c) The heat required to raise the temperature of a unit mass of a substance by one degree

The concept of heat transfer is based on:
a) The transfer of energy by conduction
b) The transfer of energy by convection
c) The transfer of energy by radiation
d) All of the above

d) All of the above

The concept of adiabatic process is defined as a process without:
a) Any change in pressure
b) Any change in volume
c) Any change in temperature
d) Any heat transfer

d) Any heat transfer

The concept of thermal equilibrium is related to:
a) The flow of heat between two objects
b) The difference in temperature between two objects
c) The absence of heat transfer between two objects
d) The balance of heat transfer between two objects

c) The absence of heat transfer between two objects

The concept of heat transfer is governed by the laws of:
a) Thermodynamics
b) Electromagnetism
c) Newtonian mechanics
d) Quantum mechanics

a) Thermodynamics

The concept of heat capacity is an extensive property, which means it depends on:
a) The amount of the substance
b) The temperature of the substance
c) The specific heat capacity of the substance
d) The pressure of the substance

a) The amount of the substance

The concept of internal energy is a state function, which means it depends only on:
a) The amount of heat transferred
b) The amount of work done
c) The initial and final states of the system
d) The temperature of the system

c) The initial and final states of the system

The concept of heat transfer is primarily based on the movement of:
a) Electrons
b) Protons
c) Neutrons
d) Energy

d) Energy

The concept of the Carnot cycle is based on the idea of:
a) Maximizing work output
b) Minimizing entropy generation
c) Optimizing heat transfer
d) Achieving thermal equilibrium

a) Maximizing work output

The concept of the entropy change of a system is related to the:
a) Heat transfer into the system
b) Temperature change of the system
c) Work done by the system
d) Change in internal energy of the system

b) Temperature change of the system

The concept of the entropy change of the universe is always:
a) Positive
b) Negative
c) Zero
d) Variable depending on the process

a) Positive

The concept of the adiabatic process is often used to describe the behavior of:
a) Ideal gases
b) Real gases
c) Solids
d) Liquids

a) Ideal gases

The concept of entropy is often associated with:
a) Disorder and randomness
b) Order and organization
c) Temperature and energy
d) Pressure and volume

a) Disorder and randomness

The concept of entropy change is a measure of the:
a) Energy transferred as heat
b) Energy transferred as work
c) Increase in disorder of a system
d) Decrease in disorder of a system

c) Increase in disorder of a system

The concept of the reversible process is often used to describe an idealized process that:
a) Occurs spontaneously and naturally
b) Occurs without any heat transfer
c) Occurs in a closed system
d) Occurs in a reversible cycle

b) Occurs without any heat transfer

The concept of the irreversible process is often used to describe a process that:
a) Occurs spontaneously and naturally
b) Occurs without any heat transfer
c) Occurs in a closed system
d) Occurs with an increase in entropy

d) Occurs with an increase in entropy

The concept of the reversible process is closely related to the:
a) Carnot cycle
b) Entropy change
c) Heat transfer
d) Enthalpy change

a) Carnot cycle

The concept of the irreversible process is closely related to the:
a) Clausius statement
b) Kelvin-Planck statement
c) Entropy change
d) Heat transfer

b) Kelvin-Planck statement

The concept of thermal equilibrium is closely related to the:
a) Zeroth law of thermodynamics
b) First law of thermodynamics
c) Second law of thermodynamics
d) Third law of thermodynamics

a) Zeroth law of thermodynamics

The concept of thermal equilibrium is based on the idea that:
a) Heat flows from a hotter object to a colder object
b) Heat flows from a colder object to a hotter object
c) Heat does not flow between objects of different temperatures
d) Heat flows in both directions between objects of different temperatures

c) Heat does not flow between objects of different temperatures

The concept of thermal equilibrium is important for:
a) Determining the direction of heat flow
b) Calculating the efficiency of a heat engine
c) Analyzing the behavior of gases
d) Studying phase transitions

a) Determining the direction of heat flow

The concept of thermal equilibrium is related to the idea that:
a) Heat is a form of energy
b) Temperature is a measure of average kinetic energy
c) Heat flows spontaneously from a higher temperature to a lower temperature
d) Heat can be converted into work

c) Heat flows spontaneously from a higher temperature to a lower temperature

The concept of the zeroth law of thermodynamics is based on the idea of:
a) Thermal equilibrium
b) Conservation of energy
c) Increase of entropy
d) Reversibility of processes