Introduction to Thermodynamics: Master the Fundamentals of Energy, Heat, and Work

Question 1

State the first law of thermodynamics:

Accepted Answer

Energy cannot be created or destroyed, but can be transformed from one form to another.

Answer

Heat and work are interchangeable forms of energy.

Answer

Entropy always increases in an isolated system.

Answer

The temperature of a system is proportional to its internal energy.

Question 2

Define the efficiency of a heat engine:

Accepted Answer

Ratio of work done by the engine to the heat input.

Answer

Ratio of heat input to the work done by the engine.

Answer

Change in internal energy divided by the heat input.

Answer

Heat rejected by the engine divided by the work done.

Question 3

An adiabatic process is characterized by:

Accepted Answer

Absence of heat transfer between the system and its surroundings.

Answer

Constant temperature throughout the process.

Answer

Irreversible increase in the system's entropy.

Answer

Work done by the system being equal to the heat transferred to the system.

Question 4

The entropy of a pure substance at absolute zero is:

Accepted Answer

Zero.

Answer

A measure of the substance's randomness or disorder.

Answer

Equal to its specific heat.

Answer

Independent of its state.

Question 5

The Gibbs free energy of a system is:

Accepted Answer

Equal to the system's enthalpy minus the product of temperature and entropy.

Answer

A measure of the maximum useful work obtainable from the system.

Answer

Independent of the system's temperature and pressure.

Answer

A measure of the disorder of the system.

Question 6

Which of the following is NOT a consequence of the second law of thermodynamics?

Accepted Answer

All natural processes are reversible.

Answer

Heat cannot flow spontaneously from lower to higher temperatures.

Answer

The entropy of the universe increases with time.

Answer

Machines cannot have 100% efficiency.

Question 7

Which of the following cycles is commonly used in power plants?

Accepted Answer

Rankine cycle

Answer

Carnot cycle

Answer

Otto cycle

Answer

Diesel cycle

Question 8

The process in which a system exchanges heat with its surroundings while its volume remains constant is called:

Accepted Answer

Isochoric process

Answer

Isobaric process

Answer

Isothermal process

Answer

Adiabatic process

Question 9

Which of the following is NOT a thermodynamic application in engineering?

Accepted Answer

Structural design for seismic loads

Answer

Design of heat exchangers

Answer

Analysis of power plants

Answer

Development of refrigeration systems

Question 10

The first law of thermodynamics states that:

Accepted Answer

The change in internal energy of a system is equal to the heat added to the system minus the work done by the system

Answer

Energy can neither be created nor destroyed

Answer

Entropy always increases in any irreversible process

Answer

Heat cannot flow spontaneously from a colder to a hotter body

Question 11

A reversible process is characterized by:

Accepted Answer

The system returning to its initial state after the process

Answer

A decrease in the entropy of the system

Answer

Work done by the system being less than the heat added to the system

Answer

The process occurring infinitely slowly

Question 12

Entropy is a measure of:

Accepted Answer

The degree of disorder or randomness within a system

Answer

The total energy content of a system

Answer

The efficiency of a heat engine

Answer

The absolute temperature of a system

Question 13

The efficiency of a refrigeration system is evaluated using its:

Accepted Answer

Coefficient of performance

Answer

Carnot efficiency

Answer

Thermal efficiency

Answer

Power factor

Question 14

What is the SI unit of energy?

Accepted Answer

Joule

Answer

Newton-meter

Answer

Calorie

Answer

Foot-pound

Question 15

Which law of thermodynamics governs the direction of spontaneous processes?

Accepted Answer

Second law

Answer

First law

Answer

Third law

Answer

Zeroth law

Question 16

What distinguishes heat from work in thermodynamics?

Accepted Answer

Heat is transferred due to a temperature difference, while work is done by a force acting through a distance.

Answer

Heat is a form of energy, while work is a force.

Answer

Heat is measured in joules, while work is measured in newtons.

Answer

Heat can be converted into work, but not vice versa.

Question 17

A closed system in thermodynamics is one that:

Accepted Answer

Exchanges only energy with its surroundings

Answer

Exchanges only mass with its surroundings

Answer

Exchanges both energy and mass with its surroundings

Answer

Exchanges neither energy nor mass with its surroundings

Question 18

The main objective of a thermodynamic cycle is to:

Accepted Answer

Convert heat into work

Answer

Transfer heat from one reservoir to another

Answer

Increase the entropy of a system

Answer

Decrease the energy of a system

Question 19

Which of the following is not a practical application of thermodynamics?

Accepted Answer

Quantum mechanics

Answer

Power generation

Answer

Refrigeration

Answer

Internal combustion engines

Question 20

According to the first law of thermodynamics, which of the following is true?

Accepted Answer

The total energy of an isolated system remains constant.

Answer

Energy can be created or destroyed.

Answer

Heat always flows from a hot body to a cold body.

Answer

The efficiency of a heat engine can exceed 100%.

Question 21

Entropy can be defined as:

Accepted Answer

The measure of the disorder or randomness of a system

Answer

The measure of the energy of a system

Answer

The measure of the heat capacity of a system

Answer

The ratio of pressure to temperature

Question 22

The specific heat of a substance is defined as:

Accepted Answer

The amount of heat required to raise the temperature of one kilogram of the substance by one degree Celsius

Answer

The ratio of the thermal conductivity to the density of the substance

Answer

The temperature at which the substance changes phase

Answer

The entropy of the substance at a given temperature

Question 23

The second law of thermodynamics implies that:

Accepted Answer

Entropy always increases in an isolated system.

Answer

Heat engines can operate at 100% efficiency.

Answer

All processes in nature are reversible.

Answer

The temperature of a system can be lowered below absolute zero.

Question 24

The enthalpy of a system is defined as:

Accepted Answer

The sum of its internal energy and the product of its pressure and volume

Answer

The change in its internal energy when it undergoes an irreversible process

Answer

The maximum amount of work it can do

Answer

The entropy of the system divided by its temperature

Question 25

According to the first law of thermodynamics, which of the following statements is true?

Accepted Answer

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

Answer

Entropy always increases in an isolated system.

Answer

Heat always flows from a hotter to a colder region.

Answer

The total energy of the universe is constantly decreasing.

Question 26

During a reversible process, the change in entropy of the system is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Equal to the heat added to the system

Question 27

The efficiency of a heat engine is defined as:

Accepted Answer

The ratio of the work output to the heat input

Answer

The ratio of the heat input to the work output

Answer

The difference between the work output and the heat input

Answer

The sum of the work output and the heat input

Question 28

The critical point of a substance is the point at which:

Accepted Answer

The liquid and gas phases become indistinguishable

Answer

The solid and liquid phases become indistinguishable

Answer

The solid and gas phases become indistinguishable

Answer

The triple point occurs

Question 29

Entropy is a measure of a system's:

Accepted Answer

Disorderliness

Answer

Orderliness

Answer

Energy

Answer

Temperature

Question 30

Which of the following is a fundamental extensive property of a thermodynamic system?

Accepted Answer

Volume

Answer

Pressure

Answer

Temperature

Answer

Specific heat capacity

Question 31

Which law of thermodynamics describes the conservation of energy in a closed system?

Accepted Answer

First law of thermodynamics

Answer

Zeroth law of thermodynamics

Answer

Third law of thermodynamics

Answer

Second law of thermodynamics

Question 32

What is the SI unit of entropy?

Accepted Answer

J/K

Answer

W

Answer

Pa

Answer

N/m

Question 33

Which of the following is an example of an open system in thermodynamics?

Accepted Answer

A room with an open window

Answer

A sealed container of gas

Answer

An isolated thermal system

Answer

A closed bottle of water

Question 34

Which of the following is not considered a fundamental thermodynamic property?

Accepted Answer

Time

Answer

Entropy

Answer

Pressure

Answer

Temperature

Question 35

The First Law of Thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed, it can only be transferred or transformed

Answer

Heat spontaneously flows from cold objects to hot objects

Answer

Entropy always increases over time

Question 36

Which of the following is an example of a closed system?

Accepted Answer

A sealed container filled with gas

Answer

The Earth's atmosphere

Answer

A lake

Answer

A room with an open window

Question 37

Which of the following processes is irreversible?

Accepted Answer

Heat transfer across a finite temperature difference

Answer

Isentropic compression

Answer

Isothermal expansion

Answer

Adiabatic compression

Question 38

Entropy of a system is a measure of:

Accepted Answer

Its randomness or disorder

Answer

Its energy

Answer

Its temperature

Question 39

The thermodynamic cycle that describes the operation of a refrigerator is:

Accepted Answer

Reversed Carnot cycle

Answer

Carnot cycle

Answer

Diesel cycle

Answer

Otto cycle

Question 40

Which of the following is **not** a recognized form of energy transfer?

Accepted Answer

Displacement

Answer

Radiation

Answer

Heat

Answer

Work

Question 41

The first law of thermodynamics states that:

Accepted Answer

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

Answer

The total amount of entropy in a closed system decreases over time.

Answer

Heat cannot flow spontaneously from a cold to a hot body.

Question 42

A system is in thermal equilibrium when:

Accepted Answer

Its temperature is constant and it is not exchanging heat with its surroundings.

Answer

Its volume is constant.

Answer

Its pressure is equal to the pressure of its surroundings.

Question 43

The efficiency of a heat engine is defined as:

Accepted Answer

The ratio of the work output to the heat input.

Answer

The product of the heat input and the work output.

Answer

The difference between the heat input and the work output.

Question 44

A reversible process is one that:

Accepted Answer

Can be reversed without changing the state of the system or its surroundings.

Answer

Requires external work to be done.

Answer

Increases the entropy of the system.

Question 45

Entropy is a measure of a system's:

Accepted Answer

Disorder

Answer

Energy

Answer

Temperature

Question 46

According to the second law of thermodynamics, which of the following is always true in an isolated system?

Accepted Answer

The total entropy increases.

Answer

The temperature decreases.

Answer

The volume expands.

Question 47

Which of the following is **not** a property of an ideal gas?

Accepted Answer

Their molecules have a finite volume.

Answer

Their molecules move randomly.

Answer

They obey the ideal gas law.

Answer

Their molecules do not interact with each other.

Question 48

Internal energy of a system refers to:

Accepted Answer

The sum of the kinetic and potential energies of its molecules.

Answer

The amount of heat required to raise its temperature by 1 degree Celsius.

Answer

The difference between its thermal energy and its potential energy.