Thermodynamics Final Exam (THERMO)
Newest 2026-2027 Updated Practice
Exam | 100 Most Tested Questions &
Verified Detailed Answers | Tutor
Verified Success Bundle
1. A closed system undergoes a process in which 500 J of heat is added and
300 J of work is done by the system. What is the change in internal energy?
A. +200 J
B. +800 J
C. -200 J
D. +300 J
Correct Answer: A. +200 J ✓
Rationale: Using the First Law of Thermodynamics, ΔU = Q − W = 500 −
300 = +200 J. The internal energy increases.
2. Which law defines the concept of temperature equivalence between
systems in thermal equilibrium?
A. First Law of Thermodynamics
B. Second Law of Thermodynamics
C. Zeroth Law of Thermodynamics
D. Third Law of Thermodynamics
Correct Answer: C. Zeroth Law of Thermodynamics ✓
Rationale: The Zeroth Law establishes that systems in thermal equilibrium
with a third system are in equilibrium with each other.
3. In an isothermal process for an ideal gas, which property remains constant?
A. Pressure
B. Temperature
, C. Volume
D. Internal energy
Correct Answer: B. Temperature ✓
Rationale: An isothermal process occurs at constant temperature, while
other properties may vary.
4. Which of the following best describes an adiabatic process?
A. Heat is added to the system
B. Heat is removed from the system
C. No heat transfer occurs
D. Temperature remains constant
Correct Answer: C. No heat transfer occurs ✓
Rationale: In an adiabatic process, Q = 0, meaning no heat exchange with
surroundings.
5. The efficiency of a Carnot engine depends primarily on:
A. Working fluid type
B. Temperature difference between reservoirs
C. Pressure of working gas
D. Volume of system
Correct Answer: B. Temperature difference between reservoirs ✓
Rationale: Carnot efficiency depends only on TH and TC, not on working
substance.
6. What is the SI unit of entropy?
A. Joule
B. Joule per Kelvin
C. Watt
D. Kelvin per Joule
Correct Answer: B. Joule per Kelvin ✓
Rationale: Entropy is energy divided by temperature, giving J/K.
7. During a phase change at constant pressure, temperature remains constant
because energy is used to:
, A. Increase kinetic energy
B. Change volume only
C. Break or form molecular bonds
D. Increase pressure
Correct Answer: C. Break or form molecular bonds ✓
Rationale: Latent heat is used for phase transitions, not temperature
change.
8. Which process occurs at constant enthalpy?
A. Isobaric
B. Isochoric
C. Joule-Thomson expansion
D. Isothermal
Correct Answer: C. Joule-Thomson expansion ✓
Rationale: In throttling (Joule-Thomson), enthalpy remains constant.
9. The Second Law of Thermodynamics implies that:
A. Energy can be created
B. Entropy of the universe always decreases
C. Entropy of an isolated system never decreases
D. Heat flows from cold to hot spontaneously
Correct Answer: C. Entropy of an isolated system never decreases ✓
Rationale: Entropy increases or remains constant in isolated systems.
10.Which quantity is conserved in all thermodynamic processes?
A. Entropy
B. Enthalpy
C. Energy
D. Temperature
Correct Answer: C. Energy ✓
Rationale: The First Law states energy is conserved in all processes.
11.A heat engine operates between 800 K and 400 K. What is its maximum
efficiency?
Newest 2026-2027 Updated Practice
Exam | 100 Most Tested Questions &
Verified Detailed Answers | Tutor
Verified Success Bundle
1. A closed system undergoes a process in which 500 J of heat is added and
300 J of work is done by the system. What is the change in internal energy?
A. +200 J
B. +800 J
C. -200 J
D. +300 J
Correct Answer: A. +200 J ✓
Rationale: Using the First Law of Thermodynamics, ΔU = Q − W = 500 −
300 = +200 J. The internal energy increases.
2. Which law defines the concept of temperature equivalence between
systems in thermal equilibrium?
A. First Law of Thermodynamics
B. Second Law of Thermodynamics
C. Zeroth Law of Thermodynamics
D. Third Law of Thermodynamics
Correct Answer: C. Zeroth Law of Thermodynamics ✓
Rationale: The Zeroth Law establishes that systems in thermal equilibrium
with a third system are in equilibrium with each other.
3. In an isothermal process for an ideal gas, which property remains constant?
A. Pressure
B. Temperature
, C. Volume
D. Internal energy
Correct Answer: B. Temperature ✓
Rationale: An isothermal process occurs at constant temperature, while
other properties may vary.
4. Which of the following best describes an adiabatic process?
A. Heat is added to the system
B. Heat is removed from the system
C. No heat transfer occurs
D. Temperature remains constant
Correct Answer: C. No heat transfer occurs ✓
Rationale: In an adiabatic process, Q = 0, meaning no heat exchange with
surroundings.
5. The efficiency of a Carnot engine depends primarily on:
A. Working fluid type
B. Temperature difference between reservoirs
C. Pressure of working gas
D. Volume of system
Correct Answer: B. Temperature difference between reservoirs ✓
Rationale: Carnot efficiency depends only on TH and TC, not on working
substance.
6. What is the SI unit of entropy?
A. Joule
B. Joule per Kelvin
C. Watt
D. Kelvin per Joule
Correct Answer: B. Joule per Kelvin ✓
Rationale: Entropy is energy divided by temperature, giving J/K.
7. During a phase change at constant pressure, temperature remains constant
because energy is used to:
, A. Increase kinetic energy
B. Change volume only
C. Break or form molecular bonds
D. Increase pressure
Correct Answer: C. Break or form molecular bonds ✓
Rationale: Latent heat is used for phase transitions, not temperature
change.
8. Which process occurs at constant enthalpy?
A. Isobaric
B. Isochoric
C. Joule-Thomson expansion
D. Isothermal
Correct Answer: C. Joule-Thomson expansion ✓
Rationale: In throttling (Joule-Thomson), enthalpy remains constant.
9. The Second Law of Thermodynamics implies that:
A. Energy can be created
B. Entropy of the universe always decreases
C. Entropy of an isolated system never decreases
D. Heat flows from cold to hot spontaneously
Correct Answer: C. Entropy of an isolated system never decreases ✓
Rationale: Entropy increases or remains constant in isolated systems.
10.Which quantity is conserved in all thermodynamic processes?
A. Entropy
B. Enthalpy
C. Energy
D. Temperature
Correct Answer: C. Energy ✓
Rationale: The First Law states energy is conserved in all processes.
11.A heat engine operates between 800 K and 400 K. What is its maximum
efficiency?
