Laws of Thermodynamics: Master the Principles of Heat and Energy

Question 1

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

Accepted Answer

Total entropy of the universe is constantly increasing.

Answer

Entropy of an isolated system always decreases.

Answer

Heat naturally flows from cold to hot.

Question 2

Which law of thermodynamics states that the total entropy of an isolated system can never decrease?

Accepted Answer

Second law

Answer

First law

Answer

Third law

Answer

Zeroth law

Question 3

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

Accepted Answer

(T1 - T2) / T1

Answer

(T2 - T1) / T1

Answer

(T2 / T1) - T1

Answer

(T1 / T2) - T1

Question 4

Which of the following is the best example of a closed system in thermodynamics?

Accepted Answer

A sealed container of gas

Answer

A room filled with air

Answer

A cup of water sitting on a table

Answer

A flowing river

Question 5

What is the maximum work that can be extracted from a reversible heat engine?

Accepted Answer

Difference between heat absorbed and released

Answer

Heat absorbed by the system

Answer

Heat released by the system

Answer

Sum of heat absorbed and released

Question 6

Which of the following is a consequence of the zeroth law of thermodynamics?

Accepted Answer

Thermal equilibrium is a transitive relation

Answer

Heat flows from hot to cold

Answer

Entropy is a measure of disorder

Answer

Heat engines cannot be 100% efficient

Question 7

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

Accepted Answer

The entropy of an isolated system tends to increase over time.

Answer

Heat can spontaneously flow from a colder to a hotter body.

Answer

The change in internal energy of a system is always equal to the heat added to the system.

Answer

The efficiency of a heat engine can be greater than 100%.

Question 8

Which of the following systems undergoes an adiabatic process?

Accepted Answer

A closed system with no heat transfer

Answer

An open system with heat transfer

Answer

A closed system with constant volume

Answer

An open system with constant pressure

Question 9

The molar specific heat capacity of a substance is defined as:

Accepted Answer

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

Answer

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

Answer

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

Answer

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

Question 10

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

Accepted Answer

All chemical reactions cease at absolute zero.

Answer

The entropy of a perfect crystal at absolute zero is zero.

Answer

The enthalpy change for a reaction approaches zero as the temperature approaches absolute zero.

Answer

The specific heat capacity of a substance approaches zero as the temperature approaches absolute zero.

Question 11

A refrigerator operates on the principle of:

Accepted Answer

Heat transfer from a hot reservoir to a cold reservoir

Answer

Heat transfer from a cold reservoir to a hot reservoir

Answer

Work done on a system

Answer

Entropy decrease

Question 12

Which of the following units is used to measure entropy?

Accepted Answer

Joules per Kelvin

Answer

Joules

Answer

Kelvins

Answer

Joules per gram

Question 13

The thermodynamic property that quantifies the disorder or randomness of a system is:

Accepted Answer

Entropy

Answer

Enthalpy

Answer

Internal energy

Answer

Gibbs free energy

Question 14

Which law of thermodynamics states that the total entropy of an isolated system can never decrease over time?

Accepted Answer

Second Law of Thermodynamics

Answer

First Law of Thermodynamics

Answer

Third Law of Thermodynamics

Answer

Zeroth Law of Thermodynamics

Question 15

Which of the following processes is inherently irreversible?

Accepted Answer

Heat transfer through a temperature gradient

Answer

Adiabatic expansion of a perfect gas

Answer

Isothermal compression of a gas

Answer

Reversible isothermal expansion

Question 16

The enthalpy change for a reaction is negative. What does this imply about the reaction?

Accepted Answer

It is exothermic.

Answer

It is endothermic.

Answer

It is at equilibrium.

Question 17

Identify an open system from the following options:

Accepted Answer

A car engine

Answer

A thermally insulated room

Answer

A sealed container of water

Answer

A closed refrigerator

Question 18

If the Gibbs free energy change for a reaction is positive at constant temperature and pressure, what can be concluded about the reaction?

Accepted Answer

It is nonspontaneous.

Answer

Its reaction rate is slow.

Answer

It is spontaneous.

Answer

It is at equilibrium.

Question 19

What happens to the entropy of a closed system undergoing an adiabatic process?

Accepted Answer

It remains unchanged.

Answer

It increases.

Answer

It decreases.

Answer

It becomes zero.

Question 20

Which of the following is not a mode of heat transfer?

Accepted Answer

Work

Answer

Radiation

Answer

Convection

Answer

Conduction