Laws of Thermodynamics: Online Learning Quizzes for Physics

Question 1

How does entropy manifest in irreversible processes? Provide real-world examples that extend beyond textbook scenarios.

Accepted Answer

Entropy increases in irreversible processes, as seen in natural phenomena like diffusion and heat transfer.

Answer

Entropy decreases in irreversible processes, violating the Second Law of Thermodynamics.

Answer

Entropy remains unchanged in irreversible processes, contradicting the principle of energy dispersion.

Question 2

State the First Law of Thermodynamics.

Accepted Answer

Energy cannot be created or destroyed, only transferred or transformed.

Answer

Entropy always increases in an isolated system.

Answer

Heat spontaneously flows from hot objects to cold objects.

Answer

The efficiency of a heat engine is always 100%.

Question 3

Express the Second Law of Thermodynamics in terms of entropy (dS).

Accepted Answer

dS ≥ 0

Answer

dS < 0

Answer

dS = 0

Answer

dS = 1

Question 4

What is the Carnot efficiency of a heat engine operating between temperatures T1 and T2?

Accepted Answer

1 - (T2 / T1)

Answer

(T1 - T2) / T1

Answer

(T1 + T2) / T1

Answer

(T2 - T1) / T1

Question 5

State a consequence of the Third Law of Thermodynamics.

Accepted Answer

Entropy of a perfect crystal is zero at absolute zero.

Answer

Absolute zero is unattainable.

Answer

The efficiency of any heat engine is limited by the Carnot efficiency.

Answer

Energy cannot be transferred from one system to another without work being done.

Question 6

Which system allows for exchange of both matter and energy with its surroundings?

Accepted Answer

A room with an open window

Answer

A sealed container of gas

Answer

A closed bottle of water

Answer

A refrigerator

Question 7

Define Gibbs free energy.

Accepted Answer

The difference between the enthalpy and entropy of a system

Answer

The maximum amount of work that can be obtained from a system

Answer

The amount of heat transferred from a system at constant temperature

Answer

The change in entropy of a system at constant pressure

Question 8

According to the First Law of Thermodynamics, the total energy of an isolated system remains:

Accepted Answer

Constant

Answer

Decreasing

Answer

Increasing

Answer

Fluctuating

Question 9

A heat engine operates between two reservoirs at temperatures T_1 and T_2. The maximum efficiency of the engine is given by:

Accepted Answer

1 - T_2 / T_1

Answer

T_1 - T_2 / T_1

Answer

T_1 + T_2 / T_1 - T_2

Answer

T_2 + T_1 / T_2 - T_1

Question 10

In an adiabatic process, the entropy of the system:

Accepted Answer

Remains constant

Answer

Always increases

Answer

Always decreases

Answer

May increase or decrease depending on the process

Question 11

A system undergoes a process where its entropy decreases. This process is:

Accepted Answer

Irreversible

Answer

Reversible

Answer

Cyclic

Answer

Adiabatic

Question 12

Which of the following statements best describes the First Law of Thermodynamics?

Accepted Answer

Energy can neither be created nor destroyed; it can only be transferred or transformed.

Answer

The entropy of a closed system tends to increase with time.

Answer

Heat always flows from hot objects to cold objects.

Answer

All thermodynamic processes are reversible.

Question 13

Which mathematical expression represents the Second Law of Thermodynamics?

Accepted Answer

dS ≥ 0

Answer

dQ = TdS

Answer

ΔU = Q - W

Answer

Cp = Cv + R

Question 14

How does heat differ from internal energy?

Accepted Answer

Heat is energy in transit, while internal energy is energy stored within a system.

Answer

Heat is a form of energy, while internal energy is not.

Answer

Internal energy is a form of energy, while heat is not.

Answer

There is no difference between heat and internal energy.

Question 15

Which of the following is a direct consequence of the Third Law of Thermodynamics?

Accepted Answer

The entropy of a pure crystalline substance at absolute zero is zero.

Answer

The entropy of a system decreases as it approaches absolute zero.

Answer

The internal energy of a system approaches infinity as it approaches absolute zero.

Answer

The specific heat of a substance approaches zero as it approaches absolute zero.

Question 16

What is the maximum possible efficiency of a Carnot engine operating between two reservoirs at temperatures T1 and T2?

Accepted Answer

1 - T2/T1

Answer

T1/T2 - 1

Answer

T1/T2

Answer

1 - T1/T2

Question 17

Which of the following scenarios violates the Second Law of Thermodynamics?

Accepted Answer

A refrigerator that transfers heat from a cold reservoir to a hot reservoir with no external work being done.

Answer

A heat pump that absorbs heat from the environment and transfers it to a warmer reservoir.

Answer

A solar panel that converts sunlight into electricity.

Answer

A battery that discharges, converting chemical energy to electrical energy.

Question 18

What is the entropy change of a system that undergoes a reversible isothermal process?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Cannot be determined without additional information.

Question 19

Which of the following statements accurately describes the First Law of Thermodynamics?

Accepted Answer

Energy is always conserved.

Answer

Energy can be generated or destroyed.

Answer

Energy can be transformed among different forms.

Answer

The total energy in the universe is continuously increasing.

Question 20

During an irreversible process, what happens to the entropy of the system?

Accepted Answer

It increases.

Answer

It decreases.

Answer

It remains constant.

Answer

It becomes negative.

Question 21

The efficiency of a heat engine is determined by which factor?

Accepted Answer

Temperature difference between hot and cold reservoirs.

Answer

Temperature of the hot reservoir alone.

Answer

Temperature of the cold reservoir alone.

Answer

Volume of the working fluid.

Question 22

Which process is considered adiabatic?

Accepted Answer

Gas expansion in a vacuum

Answer

Gas compression by a piston

Answer

Liquid-to-gas phase transition

Answer

Solid-to-liquid phase transition

Question 23

According to the Second Law of Thermodynamics, what is the fundamental limitation on the efficiency of heat engines?

Accepted Answer

The maximum efficiency is limited due to unavoidable entropy increase.

Answer

Heat engines can achieve 100% efficiency.

Answer

Heat flows spontaneously from cold to hot reservoirs.

Answer

Heat engines violate the law of conservation of energy.

Question 24

How does the heat capacity of a substance generally change as its temperature increases?

Accepted Answer

Increases

Answer

Decreases

Answer

Remains constant

Question 25

How can we enhance a refrigerator's energy efficiency by applying the principles of thermodynamics?

Accepted Answer

Minimize heat loss and maximize heat absorption, as per the First Law of Thermodynamics.

Answer

Reduce entropy within the system, as dictated by the Second Law of Thermodynamics.

Answer

Maximize heat generation and minimize heat dissipation, as implied by the First Law of Thermodynamics.

Answer

Increase the temperature gradient within the system, as suggested by the Second Law of Thermodynamics.

Question 26

Which of the following is a statement of the First Law of Thermodynamics?

Accepted Answer

The total energy of an isolated system remains constant.

Answer

Energy can be created or destroyed.

Answer

Heat can be transferred between objects at different temperatures.

Question 27

The First Law of Thermodynamics states that:

Accepted Answer

The change in internal energy of a closed system is equal to the heat transferred into the system minus the work done by the system.

Answer

Heat energy can be neither created nor destroyed, but only transferred or transformed.

Answer

The total entropy of an isolated system always decreases.

Answer

Entropy is a measure of the randomness or disorder of a system.

Question 28

Which process would violate the Second Law of Thermodynamics?

Accepted Answer

Water spontaneously freezing at room temperature.

Answer

A hot cup of coffee gradually cooling to room temperature.

Answer

A refrigerator transferring heat from its interior to its surroundings.

Answer

A hydroelectric dam converting the potential energy of water into electrical energy.

Question 29

The SI unit of entropy is the:

Accepted Answer

Joule per Kelvin

Answer

Joule

Answer

Kelvin

Answer

Watt

Question 30

The significance of entropy in thermodynamics is that it:

Accepted Answer

Determines the direction of spontaneous processes.

Answer

Measures the amount of heat energy in a system.

Answer

Is a measure of the amount of work that can be performed by a system.

Answer

Is a measure of the temperature of a system.

Question 31

According to the First Law of Thermodynamics, what happens to energy?

Accepted Answer

It cannot be created or destroyed, only transferred or transformed.

Answer

It can be created and destroyed.

Answer

It can be transferred but not transformed.

Answer

It can be created but not transferred.

Question 32

Which law of thermodynamics describes the tendency of closed systems to increase in entropy?

Accepted Answer

Second Law

Answer

First Law

Answer

Zeroth Law

Answer

Third Law

Question 33

What is the theoretical maximum efficiency of a heat engine operating between two reservoirs at different temperatures?

Accepted Answer

Carnot Efficiency

Answer

Electrical Efficiency

Answer

Mechanical Efficiency

Answer

Thermal Efficiency

Question 34

Which thermodynamic function measures the degree of molecular disorder or randomness within a system?

Accepted Answer

Entropy

Answer

Helmholtz Free Energy

Answer

Gibbs Free Energy

Answer

Enthalpy

Question 35

According to the Third Law of Thermodynamics, what is the entropy of a perfect crystal at absolute zero?

Accepted Answer

Zero

Answer

Equal to the number of atoms in the crystal

Answer

Infinity

Answer

Indeterminate

Question 36

Which thermodynamic process involves heat transfer from a higher temperature reservoir to a lower temperature reservoir?

Accepted Answer

Refrigeration

Answer

Heat Engine

Answer

Solar Cell

Answer

Carnot Cycle

Question 37

Which of the following is NOT a characteristic of an isothermal process?

Accepted Answer

Entropy increases

Answer

Volume changes

Answer

Temperature remains constant

Answer

Heat is transferred

Question 38

Which of the following is an example of an irreversible process?

Accepted Answer

Friction

Answer

Diffusion of gases

Answer

Melting of ice

Answer

Evaporation of water

Question 39

According to the First Law of Thermodynamics, the total energy of a system and its surroundings in an isolated system is what?

Accepted Answer

Constant

Answer

Increasing

Answer

Variable

Answer

Decreasing

Question 40

Which of the following statements about entropy accurately describes its characteristic?

Accepted Answer

Entropy increases in isolated systems undergoing spontaneous processes.

Answer

Entropy decreases in isolated systems undergoing spontaneous processes.

Answer

Entropy remains constant in isolated systems undergoing spontaneous processes.

Answer

Entropy is a direct measure of the total energy of a system.

Question 41

In an adiabatic process for a closed system, which of the following is true?

Accepted Answer

There is no heat transfer between the system and the surroundings.

Answer

Entropy decreases.

Answer

Temperature increases.

Question 42

Which of the following processes is irreversible?

Accepted Answer

Friction

Answer

Adiabatic expansion of an ideal gas

Answer

Isothermal compression of an ideal gas

Question 43

What does the Clausius statement of the Second Law of Thermodynamics express?

Accepted Answer

Heat cannot flow spontaneously from a colder reservoir to a hotter reservoir.

Answer

The efficiency of a heat engine can never exceed 100%.

Answer

The entropy of an isolated system always increases with time.

Question 44

Which of the following is a consequence of the Third Law of Thermodynamics?

Accepted Answer

The entropy of a perfect crystalline substance approaches zero as its temperature approaches absolute zero.

Answer

The Second Law of Thermodynamics does not apply at absolute zero.

Answer

All chemical reactions become impossible at absolute zero.

Question 45

A heat engine operates between a high-temperature reservoir at 500 K and a low-temperature reservoir at 300 K. What is the maximum possible efficiency of this engine?

Accepted Answer

40%

Answer

50%

Answer

25%

Question 46

A system absorbs 200 J of heat and does 100 J of work. What is the change in internal energy of the system?

Accepted Answer

100 J

Answer

-100 J

Answer

300 J

Answer

-300 J

Question 47

Which of the following processes is an example of irreversible process?

Accepted Answer

Friction between two surfaces

Answer

Expansion of an ideal gas in a frictionless vacuum

Answer

Melting of ice at exactly 0°C

Answer

A Carnot engine operating between two reservoirs

Question 48

The entropy of an isolated system always...

Accepted Answer

Increases

Answer

Depends on the temperature

Answer

Decreases

Answer

Stays constant

Question 49

A refrigerator removes heat from a cold reservoir and transfers it to a hot reservoir. What statement about this process is TRUE?

Accepted Answer

The refrigerator requires work input to operate.

Answer

The refrigerator operates without any work input.

Answer

The refrigerator violates the Second Law of Thermodynamics.

Answer

The refrigerator decreases the entropy of the universe.

Question 50

A gas expands adiabatically. Which of the following statements is TRUE?

Accepted Answer

No heat is exchanged between the gas and its surroundings.

Answer

The temperature of the gas remains constant.

Answer

The internal energy of the gas increases.

Question 51

A system is in thermal equilibrium with its surroundings. Which of the following statements is TRUE?

Accepted Answer

There is no net heat transfer between the system and its surroundings.

Answer

The temperature of the system is lower than the temperature of its surroundings.

Answer

The temperature of the system is higher than the temperature of its surroundings.

Question 52

A closed system undergoes a cyclic process. What is the net change in the internal energy of the system?

Accepted Answer

Zero

Answer

Negative

Answer

Depends on the path of the cycle

Answer

Positive

Question 53

Specific heat capacity of a substance is...

Accepted Answer

The amount of heat required to raise the temperature of 1 kg of the substance by 1 K

Answer

The total amount of heat the substance can hold

Answer

The rate at which the substance conducts heat

Question 54

A heat pump is used to heat a house. How does it work?

Accepted Answer

It transfers heat from the cold outside air to the warmer inside air.

Answer

It cools the house and then heats it up with a fan.

Answer

It generates heat by burning fuel.