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 12 of 36
- A. -5 J
- B. 10 J
- C. 15 J
- D. 5 J
Explanation: The change in internal energy = work done by the system + heat energy supplied to the system. The work done by the system is 5 J.
Correct answer: 5 J- A. Cyclic
- B. Free expansion
- C. Isobaric
- D. Adiabatic
Explanation: The net work done is zero in a free expansion process.In a free expansion, the gas expands into a vacuum.
Correct answer: Free expansion- A. Heat absorbed = work done on the system
- B. Heat absorbed = work done by the system
- C. Heat released = work done by the system
- D. Heat released= work done by the system+ change in internal energy
Explanation: Option A : According to the first law of thermodynamics, heat absorbed is not equal to work done on the system.
Correct answer: Heat absorbed = work done by the system- A. dQ
- B. dW
- C. dQ-dW
- D. dQ+dW
Explanation: In a thermodynamic process, the internal energy (ΔU = ΔQ - ΔW) is a state function, therefore it depends only on the initial and the final…
Correct answer: dQ-dW- A. Isothermal
- B. Adiabatic
- C. Isobaric
- D. Isochoric
Explanation: Isothermal process is the one where temperature remains constant.Isochoric process is the one where volume remains constant.Isobaric…
Correct answer: Adiabatic- A. 1st Law of thermodynamics
- B. 2nd Law of thermodynamics
- C. Law of conservation of energy
- D. Law of entropy
Explanation: An adiabatic process is one where no heat enters or leaves a system. Here, we compress a gas adiabatically inside a bicycle pump.
Correct answer: 1st Law of thermodynamics- A. 7 P1V1
- B. 8 P1V1
- C. 9 P1V1
- D. 10 P1V1
Explanation: In this problem, the process involves the pressure of the gas being proportional to the volume, which suggests a linear relationship.
Correct answer: 9 P1V1- A. 2/5
- B. 3/5
- C. 3/7
- D. 5/7
Explanation: Q=U+wU which is internal energy includes intermolecular interactions, vibrational, rotational, translational kinetic energy.In a monatomic…
Correct answer: 3/5- A. 100%
- B. 300%
- C. 200%
- D. 75%
Explanation: The correct answer is Option D: 75%. The internal energy change of an ideal gas is directly proportional to the change in temperature.
Correct answer: 75%- A. ∆Q=∆W
- B. ∆Q=∆U+∆W
- C. ∆Q=∆U
- D. ∆Q=∆U/∆W
Explanation: The correct expression for the 1st law of thermodynamics is ∆Q=∆U+∆W, which states that the heat energy added to a system (∆Q) is equal to…
Correct answer: ∆Q=∆U+∆W- A. The heating of a system equals the increase of its internal energy plus the work done on the system
- B. The increase in the internal energy of a system equals the heating of the system minus the work done by the system
- C. The increase in the internal energy of a system equals the heating of the system plus the work done by the system
- D. The work done on a system equals the increase of its thermal energy plus the heating of the system
Explanation: The first law of thermodynamics is essentially a statement of energy conservation.
Correct answer: The increase in the internal energy of a system equals the heating of the system minus the work done by the system- A. ∆U is positive, Q is zero, W is positive
- B. ∆U is negative, Q is zero, W is negative
- C. ∆U is zero, Q is zero, W is positive
- D. ∆U is positive, Q is positive, W is zero
Explanation: When the balloon bursts, the gas undergoes rapid adiabatic expansion, meaning there is no heat exchange with the surroundings (Q = 0).
Correct answer: ∆U is negative, Q is zero, W is negative- A. Qx = Qy and Ux = Uy
- B. Qx = Qy and Ux < Uy
- C. Qx < Qy and Ux < Uy
- D. Qx < Qy and Ux = Uy
Explanation: When heating occurs at constant volume, all the heat added increases the internal energy, whereas at constant pressure, some heat…
Correct answer: Qx < Qy and Ux = Uy- A. Decreases
- B. First increases and then decreases
- C. Increases
- D. Remains the same
Explanation: The correct answer is D: Remains the same. For an ideal gas, internal energy is a function of temperature only (U ∝ T).
Correct answer: Remains the same- A. 50J
- B. 90J
- C. 60J
- D. 110J
Explanation: The problem is solved using the first law of thermodynamics, which states that the change in internal energy (∆U) is equal to the heat…
Correct answer: 50J- A. Increases
- B. Remains constant
- C. Decreases
- D. Becomes Zero
Explanation: When objects are rubbed together, mechanical work is done on them, which increases their temperature.
Correct answer: Increases- A. 31.4J
- B. 3.14 x 10^7 J
- C. 3.14J
- D. None
Explanation: Q=∆U+W cyclic process i.e. ∆U=0 Q=W=Area pf P-V graph= πr² =π(Pr)(Vr) =3.14(100x103)(100)=31.4x106 J
Correct answer: 3.14 x 10^7 J- A. Isothermal
- B. Isobaric
- C. Isochoric
- D. Adiabatic
Explanation: The correct answer is Isochoric because in an isochoric process, the volume of the system remains constant, meaning no work is done by or…
Correct answer: Isochoric- A. AB, BC, CD
- B. DC, CB, BA
- C. CD, DA, AB
- D. BA, AD, DC
Explanation: In the pressure-volume diagram, an isochoric process is characterized by a constant volume (ΔV=0), which corresponds to a vertical line.
Correct answer: DC, CB, BA- A. A
- B. B
- C. C
- D. D
Explanation: During X--->Y, V↓,P↑During Y--->Z P∝1/VDuring Z--->X P=constant V↓
Correct answer: D