Pharm-D Entry Test (D Pharmacy) Physics: Thermodynamics MCQs

Practice Thermodynamics MCQs for Pharm-D Entry Test (D Pharmacy) Physics — topic-wise sets with solved answers.

Pharm-D Entry Test (D Pharmacy) Physics: Thermodynamics MCQs — sample questions

  1. Question 1

    Q1. A gas expands isothermally. What happens to its internal energy?

    • A) Increases
    • B) Remains constant
    • C) Decreases
    • D) First increases then decreases

    Answer: Remains constant

    Explanation: Internal energy remains constant in isothermal expansion for ideal gases. Other options are incorrect as they imply energy change.

  2. Question 2

    Q2. What is the SI unit of entropy?

    • A) J/K
    • B) J
    • C) W/K
    • D) K/J

    Answer: J/K

    Explanation: Entropy is measured in J/K. Other options are units for different physical quantities, not entropy.

  3. Question 3

    Q3. A heat engine operates between 500K and 300K. What is its maximum efficiency?

    • A) 20%
    • B) 30%
    • C) 40%
    • D) 60%

    Answer: 40%

    Explanation: Maximum efficiency = 1 - (T_cold/T_hot) = 1 - (300/500) = 0.4 or 40%. Other options are incorrect calculations.

  4. Question 4

    Q4. What is the process called when a system absorbs heat without a change in temperature?

    • A) Isothermal
    • B) Adiabatic
    • C) Isobaric
    • D) Isochoric

    Answer: Isothermal

    Explanation: Isothermal process occurs at constant temperature. Other options describe different thermodynamic processes.

  5. Question 5

    Q5. For an ideal gas, which of the following is true during an adiabatic expansion?

    • A) Temperature remains constant
    • B) Internal energy remains constant
    • C) Work done is zero
    • D) Temperature decreases

    Answer: Temperature decreases

    Explanation: In adiabatic expansion, temperature decreases as work is done at the expense of internal energy. Other options are incorrect.

  6. Question 6

    Q6. The zeroth law of thermodynamics is related to which concept?

    • A) Temperature
    • B) Internal Energy
    • C) Entropy
    • D) Heat Capacity

    Answer: Temperature

    Explanation: Zeroth law of thermodynamics defines temperature. Other options are related to different thermodynamic concepts.

  7. Question 7

    Q7. A refrigerator works on the principle of

    • A) Joule-Thomson effect
    • B) Carnot cycle
    • C) Reversed Carnot cycle
    • D) First law of thermodynamics

    Answer: Reversed Carnot cycle

    Explanation: Refrigerator works on reversed Carnot cycle, transferring heat from cold to hot. Other options are related but not the principle.

  8. Question 8

    Q8. The change in internal energy of a system is given by

    • A) ΔU = Q + W
    • B) ΔU = Q - W
    • C) ΔU = W - Q
    • D) ΔU = Q * W

    Answer: ΔU = Q + W

    Explanation: First law of thermodynamics states ΔU = Q + W, where W is work done on the system. Other options are incorrect sign conventions.

  9. Question 9

    Q9. For a given isothermal process, the work done is maximum when

    • A) Pressure is constant
    • B) Volume is constant
    • C) The process is reversible
    • D) The process is irreversible

    Answer: The process is reversible

    Explanation: Maximum work is done in a reversible isothermal expansion. Other options do not maximize work done.

  10. Question 10

    Q10. The coefficient of performance (COP) of a refrigerator is given by

    • A) T_cold / (T_hot - T_cold)
    • B) T_hot / (T_hot - T_cold)
    • C) T_cold / T_hot
    • D) T_hot / T_cold

    Answer: T_cold / (T_hot - T_cold)

    Explanation: COP = T_cold / (T_hot - T_cold) for a refrigerator. Other options are incorrect or related to different quantities.

  11. Question 11

    Q11. What happens to the entropy of the universe in a spontaneous process?

    • A) Remains constant
    • B) Decreases
    • C) Increases
    • D) First decreases then increases

    Answer: Increases

    Explanation: Entropy of the universe always increases in a spontaneous process. Other options are incorrect as they violate the second law.

  12. Question 12

    Q12. The internal energy of an ideal gas depends on

    • A) Volume only
    • B) Temperature only
    • C) Pressure only
    • D) Both temperature and volume

    Answer: Temperature only

    Explanation: For an ideal gas, internal energy is a function of temperature only. Other options are incorrect as they imply additional dependencies.

  13. Question 13

    Q13. A thermodynamic process occurs at constant volume. What is it called?

    • A) Isobaric
    • B) Isothermal
    • C) Isochoric
    • D) Adiabatic

    Answer: Isochoric

    Explanation: Isochoric process occurs at constant volume. Other options describe different thermodynamic processes.

  14. Question 14

    Q14. The efficiency of a Carnot engine is 0.5. What is the temperature of the cold reservoir if the hot reservoir is at 500K?

    • A) 250K
    • B) 200K
    • C) 300K
    • D) 400K

    Answer: 250K

    Explanation: Efficiency = 1 - (T_cold/T_hot). Given efficiency = 0.5 and T_hot = 500K, T_cold = 250K. Other options are incorrect temperatures.

  15. Question 15

    Q15. In a cyclic process, the change in internal energy is

    • A) Positive
    • B) Negative
    • C) Zero
    • D) Depends on the path

    Answer: Zero

    Explanation: In a cyclic process, the system returns to its initial state, so ΔU = 0. Other options imply a change in state.

  16. Question 16

    Q16. What is the condition for a process to be reversible?

    • A) It must be adiabatic
    • B) It must be isothermal
    • C) It must be quasi-static
    • D) It must be isobaric

    Answer: It must be quasi-static

    Explanation: A reversible process must be quasi-static and have no dissipative forces. Other options describe specific types of processes, not the condition for reversibility.

  17. Question 17

    Q17. The second law of thermodynamics implies that

    • A) Heat can flow from cold to hot spontaneously
    • B) Perpetual motion machines of the second kind are possible
    • C) The total entropy of an isolated system can never decrease
    • D) The efficiency of a heat engine can be 100%

    Answer: The total entropy of an isolated system can never decrease

    Explanation: The second law states that total entropy of an isolated system always increases or remains constant. Other options violate the second law.

  18. Question 18

    Q18. For an ideal gas, the molar specific heat at constant pressure is

    • A) Greater than at constant volume
    • B) Less than at constant volume
    • C) Equal to at constant volume
    • D) Zero

    Answer: Greater than at constant volume

    Explanation: C_p > C_v because at constant pressure, the gas does work in addition to the energy required to raise the temperature. Other options are incorrect comparisons.

  19. Question 19

    Q19. In an adiabatic process, the heat transfer (Q) is

    • A) Maximum
    • B) Zero
    • C) Minimum
    • D) Depends on the gas

    Answer: Zero

    Explanation: In an adiabatic process, Q = 0 by definition. Other options are incorrect as they imply heat transfer.

  20. Question 20

    Q20. A thermodynamic system's internal energy increases by 100 J when 200 J of heat is added and it does 100 J of work. Is this possible?

    • A) Yes, always
    • B) No, never
    • C) Yes, if the process is isobaric
    • D) Yes, if the process is adiabatic

    Answer: No, never

    Explanation: ΔU = Q + W = 200 J - 100 J = 100 J, which matches the given increase in internal energy, so it's possible but not related to being isobaric or adiabatic. The statement is actually true according to the first law.

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