Free Thermodynamics MCQs with Answers
714 Thermodynamics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Thermal equilibrium and heat explain how temperature and energy transfer are related, while molar specific heats describe the heat required by a gas at constant volume or constant pressure. The first law connects heat supplied, work done and change in internal energy, with sign conventions kept distinct from temperature changes.
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Read the Thermodynamics notesFree MDCAT chapter notes with key terms714 questions · page 10 of 36
- A. Q = W
- B. Q = ∆U
- C. Q= U + W
- D. W = -∆U
Explanation: The First law of thermodynamics is written as:∆Q = ∆U + ∆WIn adiabatic conditions, ∆Q = 0This is because adiabatic conditions imply that…
Correct answer: W = -∆U- A. In system A
- B. In system B
- C. Cannot be predicted
- D. Change is zero in both. (both are cyclic)
Explanation: In a cyclic process, the system undergoes a series of changes and returns to its initial state.
Correct answer: Change is zero in both. (both are cyclic)- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Adiabatic expansion and compression are characterized by a more rapid change in pressure and volume.
Correct answer: Option A- A. 27 0C
- B. 127 0C
- C. 300 0 C
- D. 600 0 C
Explanation: 327k means 327-273-54 degrees celsius. For a reservoir to work at a 50% efficiency, the low reservoir must have half the temperature than…
Correct answer: 27 0C- A. Change in volume
- B. Change in temperature and volume
- C. Change in temperature
- D. Path followed to change internal energy
Explanation: The internal energy of an ideal gas depends solely on its temperature. According to the ideal gas law and the kinetic theory of gases, the…
Correct answer: Change in temperature- A. 1:3
- B. 1:2
- C. 2:3
- D. 2:1
Explanation: To find the value of the efficiency ratio (ηA:ηB) between two heat engines A and B, we need to compare the ratios of their heat outputs…
Correct answer: 1:2- A. -200 J
- B. +200 J
- C. 100 J
- D. 0 J
Explanation: In an adiabatic system no heat exchange between the system and surrounding.
Correct answer: +200 J- A. -300 J
- B. 300 J
- C. -100 J
- D. 0 J
Explanation: ΔQ=ΔW+ΔU100 J =400 J+ΔU100 J - 400 J= ΔUΔU=300 J
Correct answer: 300 J- A. When we supply heat to a body we do work on it
- B. When we do work on a body we supply heat to it
- C. The temperature of a body can be increased by doing work on it
- D. Heat and work are not inter convertible
Explanation: From the given statement it can be derived Q= W and hence Internal energy change must me zero.
Correct answer: The temperature of a body can be increased by doing work on it- A. Q
- B. W
- C. Q + W
- D. Q - W
Explanation: Internal energy would be the same irrespective of the path.U (internal energy) = Q - W
Correct answer: Q - W- A. 50J
- B. 60J
- C. 90J
- D. 110J
Explanation: The change in internal energy is 20-40 = -20 J so the final internal energy is x where x-70= -20X=50
Correct answer: 50J- A. 1400 J
- B. 1200 J
- C. 1700 J
- D. 1300 J
Explanation: T₁ =400kT₂-200kW=800JWe know efficiency=1-T2/T1-WW/Q=1-200/400=600/0.5=1200JAs it is numerical, it can have only one answer.
Correct answer: 1200 J- A. 100J
- B. 200J
- C. 400J
- D. 600J
Explanation: If the efficiency of the engine is 25%, then the energy that is output for useful work is 25% of the input energy, which is 25% of 800 J=…
Correct answer: 600J- A. I, II and III
- B. I and II only
- C. I and III only
- D. II and III only
Explanation: The internal energy of a system is the total energy contained within, including kinetic and potential energies associated with the motion…
Correct answer: I, II and III- A. I only
- B. I and II
- C. III only
- D. II and III
Explanation: In an adiabatic process, there is no heat exchange with the surroundings Adiabatic compression is usually depicted as a curve on a PV…
Correct answer: III only- A. -1690 J
- B. 0 J
- C. 1690 J
- D. 2490 J
Explanation: The First Law of Thermodynamics states that the change in internal energy (ΔU) of a system is equal to the heat added to the system (Q)…
Correct answer: 1690 J- A. 25%
- B. 44.6%
- C. 55.4%
- D. 75%
Explanation: The maximum possible efficiency of a heat engine operating between temperature limits is given by the Carnot efficiency formula:Efficiency…
Correct answer: 44.6%- A. w = ∆u = Q
- B. Q = -w
- C. Q = w
- D. w = -∆u
Explanation: An adiabatic process is one in which no heat is gained or lost by the system.
Correct answer: w = -∆u- A. Zeroth law of thermodynamics
- B. First law of thermodynamics
- C. Second law of thermodynamics
- D. Both, the first and second laws of thermodynamics
Explanation: Conversion of heat energy completely into work implies no loss of energy.
Correct answer: Second law of thermodynamics- A. Temperature
- B. Volume
- C. Pressure
- D. Amount of heat
Explanation: In adiabatic process, heat remains constant. Q =constant ΔQ = O Hence, option D is correct.
Correct answer: Amount of heat