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 Thermodynamics MCQs for Preparation.

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## Thermodynamics Online MCQs with Answers

Which law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed?

a) Zeroth law
b) First law
c) Second law
d) Third law

b) First law

The SI unit of heat is:
a) Joule (J)
b) Watt (W)
c) Calorie (cal)
d) Kelvin (K)

a) Joule (J)

The branch of thermodynamics that deals with the relationships between heat, work, and energy transfer is called:
a) Classical thermodynamics
b) Statistical thermodynamics
c) Chemical thermodynamics
d) Engineering thermodynamics

a) Classical thermodynamics

The internal energy of a system is:
a) the total energy of the system
b) the energy associated with the motion of the system
c) the energy associated with the position of the system
d) the energy associated with the interactions between the particles of the system

a) the total energy of the system

Which law of thermodynamics states that heat cannot spontaneously flow from a colder object to a hotter object?
a) Zeroth law
b) First law
c) Second law
d) Third law

c) Second law

The process in which a system releases heat to the surroundings is called:
b) isothermal process
c) exothermic process
d) endothermic process

c) exothermic process

Which law of thermodynamics states that as the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value?
a) Zeroth law
b) First law
c) Second law
d) Third law

d) Third law

The transfer of heat between two objects that are in direct contact with each other is called:
a) conduction
b) convection

a) conduction

The branch of thermodynamics that deals with the behavior of individual particles in a system is called:
a) Classical thermodynamics
b) Statistical thermodynamics
c) Chemical thermodynamics
d) Engineering thermodynamics

b) Statistical thermodynamics

The total entropy of an isolated system always:
a) increases
b) decreases
c) remains constant
d) fluctuates randomly

a) increases

The change in internal energy of a system is equal to the heat added to the system minus the work done by the system. This statement represents:
a) Zeroth law
b) First law
c) Second law
d) Third law

b) First law

The transfer of heat through the movement of fluid is called:
a) conduction
b) convection

b) convection

The entropy of a system tends to increase in which type of process?
a) reversible process
b) irreversible process
d) isothermal process

b) irreversible process

The measure of the disorder or randomness of a system is called:
a) temperature
b) internal energy
c) entropy
d) enthalpy

c) entropy

The process in which a system absorbs heat from the surroundings is called:
b) isothermal process
c) exothermic process
d) endothermic process

d) endothermic process

The transfer of heat through electromagnetic waves is called:
a) conduction
b) convection

The absolute zero on the Kelvin scale is:
a) 0 K
b) -273 K
c) 273 K
d) 373 K

b) -273 K

The enthalpy of a system is equal to:
a) internal energy plus pressure times volume
b) internal energy minus pressure times volume
c) pressure times volume
d) internal energy plus pressure divided by volume

a) internal energy plus pressure times volume

Which law of thermodynamics states that if two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other?
a) Zeroth law
b) First law
c) Second law
d) Third law

a) Zeroth law

The process in which a system undergoes a change without the exchange of heat with its surroundings is called:
b) isothermal process
c) exothermic process
d) endothermic process

The change in entropy of a system can be calculated by dividing the heat added or removed from the system by the system’s:
a) temperature
b) pressure
c) volume
d) enthalpy

a) temperature

The efficiency of a heat engine is given by the ratio of:
a) work output to heat input
b) heat input to work output
c) temperature difference to heat input
d) temperature difference to work output

a) work output to heat input

The process in which a system undergoes a change while maintaining constant temperature is called:
b) isothermal process
c) exothermic process
d) endothermic process

b) isothermal process

The entropy change of a system in a reversible process is equal to:
a) zero
b) positive
c) negative
d) infinity

a) zero

The state of a system in which it has the highest possible entropy is called:
a) equilibrium state
b) enthalpy state
c) ordered state
d) disordered state

d) disordered state

The process in which a system undergoes a change without the transfer of heat or matter is called:
b) isothermal process
c) reversible process
d) irreversible process

c) reversible process

The point at which a substance undergoes a phase change from solid to liquid or liquid to gas is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

a) melting point

The process in which a gas is compressed or expanded at a constant temperature is called:
b) isothermal process
c) reversible process
d) irreversible process

b) isothermal process

The process in which a gas is compressed or expanded without the transfer of heat is called:
b) isothermal process
c) reversible process
d) irreversible process

The heat capacity of a system is defined as the amount of heat required to:
a) increase its temperature by 1 degree Celsius
b) increase its temperature by 1 degree Fahrenheit
c) increase its temperature by 1 Kelvin
d) increase its temperature by 1 degree Rankine

a) increase its temperature by 1 degree Celsius

The process in which a substance undergoes a phase change from gas to liquid is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The process in which a substance undergoes a phase change from liquid to gas is called:
a) melting
b) boiling
c) freezing
d) condensation

b) boiling

The process in which a substance undergoes a phase change from solid to gas without passing through the liquid phase is called:
a) sublimation
b) deposition
c) fusion
d) vaporization

a) sublimation

The process in which a substance undergoes a phase change from gas to solid without passing through the liquid phase is called:
a) sublimation
b) deposition
c) fusion
d) vaporization

b) deposition

The enthalpy change of a system can be calculated by dividing the heat added or removed from the system by the system’s:
a) temperature
b) pressure
c) volume
d) entropy

b) pressure

The heat required to raise the temperature of a unit mass of a substance by 1 degree Celsius is called:
a) specific heat capacity
b) latent heat
c) enthalpy
d) entropy

a) specific heat capacity

The process in which a substance undergoes a phase change from liquid to solid is called:
a) melting
b) boiling
c) freezing
d) condensation

c) freezing

The heat required to change the phase of a substance without a change in temperature is called:
a) specific heat capacity
b) latent heat
c) enthalpy
d) entropy

b) latent heat

The point at which a substance undergoes a phase change from gas to liquid at a specific pressure is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

b) boiling point

The process in which a substance undergoes a phase change from solid to liquid at a specific temperature is called:
a) melting
b) boiling
c) freezing
d) condensation

a) melting

The point at which a substance undergoes a phase change from liquid to gas at a specific pressure is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

b) boiling point

The process in which a substance undergoes a phase change from liquid to solid at a specific temperature is called:
a) melting
b) boiling
c) freezing
d) condensation

c) freezing

The process in which a substance undergoes a phase change from gas to solid is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The enthalpy change of a system at constant pressure is equal to the heat:
b) removed from the system
c) added or removed from the system
d) transferred within the system

c) added or removed from the system

The point at which a substance undergoes a phase change from solid to liquid at a specific pressure is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

a) melting point

The point at which a substance undergoes a phase change from liquid to solid at a specific pressure is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

c) freezing point

The process in which a substance undergoes a phase change from solid to liquid is called:
a) melting
b) boiling
c) freezing
d) condensation

a) melting

The process in which a substance undergoes a phase change from liquid to gas is called:
a) melting
b) boiling
c) freezing
d) condensation

b) boiling

The process in which a substance undergoes a phase change from liquid to solid is called:
a) melting
b) boiling
c) freezing
d) condensation

c) freezing

The process in which a substance undergoes a phase change from gas to liquid is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The enthalpy change of a system is positive during an:
a) exothermic process
b) endothermic process
d) isothermal process

b) endothermic process

The enthalpy change of a system is negative during an:
a) exothermic process
b) endothermic process
d) isothermal process

a) exothermic process

The entropy change of a system is positive during an:
a) exothermic process
b) endothermic process
d) isothermal process

b) endothermic process

The entropy change of a system is negative during an:
a) exothermic process
b) endothermic process
d) isothermal process

a) exothermic process

The process in which a substance undergoes a phase change from solid to gas without passing through the liquid phase is called:
a) sublimation
b) deposition
c) fusion
d) vaporization

a) sublimation

The process in which a substance undergoes a phase change from gas to solid without passing through the liquid phase is called:
a) sublimation
b) deposition
c) fusion
d) vaporization

b) deposition

The heat required to change the phase of a unit mass of a substance is called:
a) specific heat capacity
b) latent heat
c) enthalpy
d) entropy

b) latent heat

The process in which a substance undergoes a phase change from liquid to gas at a specific temperature is called:
a) melting
b) boiling
c) freezing
d) condensation

b) boiling

The process in which a substance undergoes a phase change from gas to liquid at a specific temperature is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The enthalpy change of a system at constant volume is equal to the heat:
b) removed from the system
c) added or removed from the system
d) transferred within the system

c) added or removed from the system

The point at which a substance undergoes a phase change from liquid to solid at a specific temperature is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

c) freezing point

The point at which a substance undergoes a phase change from solid to liquid at a specific temperature is called:
a) melting point
b) boiling point
c) freezing point
d) condensation point

a) melting point

The process in which a substance undergoes a phase change from solid to gas is called:
a) melting
b) boiling
c) freezing
d) condensation

a) melting

The process in which a substance undergoes a phase change from gas to solid is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The enthalpy change of a system at constant pressure is equal to the heat:
b) removed from the system
c) added or removed from the system
d) transferred within the system

c) added or removed from the system

The heat capacity of a system is defined as the amount of heat required to:
a) increase its temperature by 1 degree Celsius
b) increase its temperature by 1 degree Fahrenheit
c) increase its temperature by 1 Kelvin
d) increase its temperature by 1 degree Rankine

a) increase its temperature by 1 degree Celsius

The process in which a substance undergoes a phase change from liquid to solid is called:
a) melting
b) boiling
c) freezing
d) condensation

c) freezing

The process in which a substance undergoes a phase change from gas to liquid is called:
a) melting
b) boiling
c) freezing
d) condensation

d) condensation

The heat required to raise the temperature of a unit mass of a substance by 1 degree Fahrenheit is called:
a) specific heat capacity
b) latent heat
c) enthalpy
d) entropy