Thermodynamics MCQs
What is the study of the relationships between heat, work, and energy called?
Thermodynamics
Mechanics
Electromagnetism
Quantum Mechanics
Which of the following is a statement of the First Law of Thermodynamics?
Energy cannot be created or destroyed, only transferred or converted from one form to another.
Heat flows spontaneously from a hotter body to a colder body.
The entropy of a perfect crystal at absolute zero is exactly equal to zero.
For every action, there is an equal and opposite reaction.
What is the internal energy of an ideal gas dependent on?
Temperature only
Pressure only
Volume only
Pressure and volume
In an isothermal process, which of the following remains constant?
Temperature
Pressure
Volume
Heat
In an adiabatic process, what is true about the heat transfer?
There is no heat transfer.
Heat is constantly added to the system.
Heat is constantly removed from the system.
Heat transfer is equal to the work done.
What is the work done by a gas during an isobaric expansion?
W = PΔV
W = VΔP
W = nRT ln(V₂/V₁)
W = 0
The efficiency of a Carnot engine depends on:
The temperatures of the hot and cold reservoirs
The working substance
The pressure of the working substance
The volume of the working substance
What is the measure of the disorder or randomness of a system called?
Entropy
Enthalpy
Internal energy
Gibbs free energy
According to the Second Law of Thermodynamics, the entropy of an isolated system:
Always increases or remains constant
Always decreases
Remains constant
Can either increase or decrease
What is the SI unit of entropy?
Joules per Kelvin (J/K)
Joules (J)
Kelvin (K)
Watts (W)
A refrigerator is an example of a:
Heat pump
Heat engine
Perpetual motion machine
Carnot engine
If 8400 J of heat is added to a 2 kg block of copper, raising its temperature from 10°C to 20°C, what is the specific heat capacity of copper?
420 J/(kg·K)
840 J/(kg·K)
42 J/(kg·K)
8400 J/(kg·K)
The molar specific heat at constant pressure (Cₚ) is always greater than the molar specific heat at constant volume (Cᵥ) for an ideal gas because:
Work is done by the gas when it expands at constant pressure.
The temperature of the gas increases more at constant pressure.
The pressure of the gas increases more at constant pressure.
The internal energy of the gas increases more at constant pressure.
The relationship between Cₚ and Cᵥ for an ideal gas is:
Cₚ - Cᵥ = R
Cₚ + Cᵥ = R
Cₚ / Cᵥ = R
Cᵥ - Cₚ = R
The triple point of water is:
The temperature and pressure at which water can exist in equilibrium as a solid, liquid, and gas.
The boiling point of water at standard atmospheric pressure.
The freezing point of water at standard atmospheric pressure.
The critical point of water.
Which of the following processes is irreversible?
The diffusion of gases
A Carnot cycle
Slow compression of a gas in a cylinder
The melting of ice at 0°C
The work done in a cyclic process is equal to:
The area enclosed by the cycle on a P-V diagram
Zero
The heat absorbed by the system
The change in internal energy
A heat engine takes in 100 J of heat from a hot reservoir and exhausts 60 J of heat to a cold reservoir. What is its efficiency?
The equation of state for an ideal gas is:
PV = nRT
P₁V₁ = P₂V₂
V₁/T₁ = V₂/T₂
P₁/T₁ = P₂/T₂
The zeroth law of thermodynamics deals with:
Thermal equilibrium
Conservation of energy
Direction of heat flow
Absolute zero
The specific heat capacity of a substance is the amount of heat required to raise the temperature of:
1 kg of the substance by 1 K
1 mole of the substance by 1 K
The entire substance by 1 K
1 g of the substance by 1 °C
What is the process called when a substance changes directly from a solid to a gas?
Sublimation
Evaporation
Condensation
Melting
The latent heat of fusion is the heat required to:
Change a unit mass of a substance from a solid to a liquid at its melting point.
Change a unit mass of a substance from a liquid to a gas at its boiling point.
Raise the temperature of a unit mass of a substance by 1 K.
Change a unit mass of a substance from a solid to a gas at its sublimation point.
Which of the following is an extensive property?
Volume
Temperature
Pressure
Density
Which of the following is an intensive property?
Density
Mass
Volume
Internal energy
The efficiency of a practical heat engine is always:
Less than the efficiency of a Carnot engine
Greater than the efficiency of a Carnot engine
Equal to the efficiency of a Carnot engine
Always 100%
The first law of thermodynamics is a statement of:
Conservation of energy
Conservation of momentum
Conservation of charge
Conservation of mass
In an isochoric process, what remains constant?
Volume
Temperature
Pressure
Heat
In an isobaric process, what remains constant?
Pressure
Temperature
Volume
Heat
The change in internal energy of a system in a cyclic process is:
Zero
Positive
Negative
Equal to the work done
Heat can be transferred by:
Conduction, convection, and radiation
Conduction and convection only
Convection and radiation only
Conduction and radiation only
The transfer of heat by the movement of a fluid is called:
Convection
Conduction
Radiation
Advection
The transfer of heat through electromagnetic waves is called:
Radiation
Conduction
Convection
Refraction
The transfer of heat through direct contact is called:
Conduction
Convection
Radiation
Induction
The absolute zero of temperature is:
The work done on a system is considered:
Negative
Positive
Zero
Infinite
The work done by a system is considered:
Positive
Negative
Zero
Infinite
The heat absorbed by a system is considered:
Positive
Negative
Zero
Infinite
The heat released by a system is considered:
Negative
Positive
Zero
Infinite
The coefficient of performance of a refrigerator is given by:
The coefficient of performance of a heat pump is given by:
A Carnot engine operates between a hot reservoir at 327°C and a cold reservoir at 27°C. What is its theoretical maximum efficiency?
A process that can be reversed without leaving any change in the system or the surroundings is called:
A reversible process
An irreversible process
A spontaneous process
A non-spontaneous process
Which of the following is an example of a state function?
Internal energy
Work
Heat
Both work and heat
Which of the following is an example of a path function?
Work
Temperature
Pressure
Volume
The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero is:
Zero
Infinite
Positive
Negative
A system that can exchange both energy and matter with its surroundings is called:
An open system
A closed system
An isolated system
A thermodynamic system
A system that can exchange energy but not matter with its surroundings is called:
A closed system
An open system
An isolated system
A mechanical system
A system that cannot exchange either energy or matter with its surroundings is called:
An isolated system
An open system
A closed system
A chemical system
The internal energy of a system can be changed by:
Heat and work
Heat only
Work only
Neither heat nor work
The temperature of a substance is a measure of the:
Average kinetic energy of its molecules
Total kinetic energy of its molecules
Average potential energy of its molecules
Total energy of its molecules
The specific heat of a gas in an isothermal process is:
Infinite
Zero
Positive
Negative
The specific heat of a gas in an adiabatic process is:
Zero
Infinite
Positive
Negative
The ratio of the molar specific heats, γ = Cₚ/Cᵥ, for a monatomic gas is:
The ratio of the molar specific heats, γ = Cₚ/Cᵥ, for a diatomic gas is:
The work done in an isochoric process is:
Zero
PΔV
nRT ln(V₂/V₁)
Negative
A Carnot cycle consists of:
Two isothermal and two adiabatic processes
Two isobaric and two isochoric processes
Two isothermal and two isobaric processes
Two adiabatic and two isochoric processes
The efficiency of a Carnot engine is given by:
1 - (Tc/Th)
1 - (Th/Tc)
Tc/Th
Th/Tc
The first law of thermodynamics can be written as:
ΔU = Q - W
ΔU = W - Q
ΔQ = U - W
ΔW = Q - U
The change in entropy is defined as:
ΔS = ΔQ/T
ΔS = ΔQ * T
ΔS = T/ΔQ
ΔS = ΔT/Q
The area under a T-S diagram represents:
Heat transferred
Work done
Change in internal energy
Change in enthalpy
A perpetual motion machine of the first kind is impossible because it would violate the:
First law of thermodynamics
Second law of thermodynamics
Third law of thermodynamics
Zeroth law of thermodynamics
A perpetual motion machine of the second kind is impossible because it would violate the:
Second law of thermodynamics
First law of thermodynamics
Third law of thermodynamics
Zeroth law of thermodynamics
The Clausius statement of the second law of thermodynamics states that:
Heat cannot spontaneously flow from a colder body to a hotter body.
It is impossible for a heat engine to have 100% efficiency.
The entropy of an isolated system always increases.
Energy cannot be created or destroyed.
The Kelvin-Planck statement of the second law of thermodynamics states that:
It is impossible to construct a heat engine that is 100% efficient.
Heat cannot spontaneously flow from a colder body to a hotter body.
The entropy of an isolated system always increases.
Energy cannot be created or destroyed.
The heat capacity of a body is the amount of heat required to raise its temperature by:
The process of converting a liquid to a vapor at a temperature below its boiling point is called:
Evaporation
Boiling
Sublimation
Condensation
The amount of heat required to change the state of a substance without changing its temperature is called:
Latent heat
Specific heat
Heat capacity
Thermal energy
The latent heat of vaporization is the heat required to:
Change a unit mass of a substance from a liquid to a gas at its boiling point.
Change a unit mass of a substance from a solid to a liquid at its melting point.
Raise the temperature of a unit mass of a substance by 1 K.
Change a unit mass of a substance from a solid to a gas at its sublimation point.
The critical temperature of a gas is the temperature:
Above which it cannot be liquefied, no matter how great the pressure.
At which it liquefies at atmospheric pressure.
At which it solidifies at atmospheric pressure.
At which its volume is zero.
The Joule-Thomson effect describes the change in temperature of a gas when it is:
Forced through a porous plug or a narrow opening
Heated at constant volume
Compressed adiabatically
Expanded isothermally
For an ideal gas, the Joule-Thomson coefficient is:
Zero
Positive
Negative
Infinite
The temperature at which the Joule-Thomson coefficient changes sign is called the:
Inversion temperature
Critical temperature
Boiling point
Triple point
The mean free path of a gas molecule is the average distance traveled:
Between two successive collisions
In one second
From one wall of the container to another
Before it escapes from the container
The pressure of an ideal gas is proportional to the:
Average kinetic energy of the molecules
Average potential energy of the molecules
Total kinetic energy of the molecules
Total energy of the molecules
The root mean square speed of the molecules of a gas is proportional to:
The square root of the absolute temperature
The absolute temperature
The square of the absolute temperature
The reciprocal of the absolute temperature
The Maxwell-Boltzmann distribution describes the:
Distribution of speeds of molecules in a gas
Distribution of positions of molecules in a gas
Distribution of energies of molecules in a gas
Distribution of pressures of molecules in a gas
The law of equipartition of energy states that the average energy associated with each degree of freedom of a molecule is:
A monatomic gas has how many degrees of freedom?
A diatomic gas has how many degrees of freedom at ordinary temperatures?
The van der Waals equation of state is a modification of the ideal gas law that takes into account:
The finite volume of molecules and the intermolecular forces
The quantum mechanical effects of molecules
The relativistic effects of molecules
The vibrational motion of molecules
Stefan's law states that the total energy radiated per unit surface area of a black body per unit time is proportional to the:
Fourth power of the absolute temperature
Absolute temperature
Square of the absolute temperature
Cube of the absolute temperature
Wien's displacement law states that the peak wavelength of black-body radiation is:
Inversely proportional to the absolute temperature
Directly proportional to the absolute temperature
Proportional to the square of the absolute temperature
Proportional to the fourth power of the absolute temperature
A black body is an object that:
Absorbs all radiation incident upon it
Reflects all radiation incident upon it
Transmits all radiation incident upon it
Is black in color
The emissivity of a black body is:
The thermal conductivity of a material is a measure of its ability to:
Conduct heat
Store heat
Radiate heat
Resist heat flow
The rate of heat conduction through a material is proportional to the:
Temperature gradient
Temperature
Length of the material
Density of the material
A system absorbs 2000 J of heat from its surroundings and does 500 J of work on its surroundings. What is the change in the internal energy of the system?
The SI unit of thermal conductivity is:
W/(m·K)
W·m/K
W/(m²·K)
J/(kg·K)
Newton's law of cooling states that the rate of loss of heat from a body is proportional to the:
Difference in temperature between the body and its surroundings
Temperature of the body
Temperature of the surroundings
Surface area of the body
The thermodynamic temperature scale is also known as the:
Kelvin scale
Celsius scale
Fahrenheit scale
Rankine scale
The triple point of water is defined to be exactly:
273.16 K
273.15 K
0.01 °C
0 K
The efficiency of a heat engine is defined as the ratio of:
Work output to heat input
Heat input to work output
Work output to heat output
Heat output to work output
The entropy of the universe is:
Always increasing
Always decreasing
Constant
Zero
Which statement best describes a reversible process?
It can be reversed by making an infinitesimally small change in conditions
It occurs at a rapid rate
It proceeds extremely slowly to maintain equilibrium
It takes place without any frictional losses
All natural processes are:
Irreversible
Reversible
Isothermal
Adiabatic
The enthalpy of a system is defined as:
H = U + PV
H = U - PV
H = PV - U
H = U + P/V
The change in enthalpy is equal to the heat transferred at constant:
Pressure
Volume
Temperature
Entropy
The Gibbs free energy of a system is defined as:
G = H - TS
G = H + TS
G = TS - H
G = H - T/S
A spontaneous process occurs at constant temperature and pressure if the change in Gibbs free energy is:
Negative
Positive
Zero
Infinite
A gas inside a piston expands from an initial volume of 0.2 m³ to a final volume of 0.5 m³ at a constant pressure of 150 kPa. How much work is done by the gas?
The Helmholtz free energy of a system is defined as:
A = U - TS
A = U + TS
A = TS - U
A = U - T/S
Other Physics Topics MCQs
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