Free First Law of Thermodynamics MCQs with Answers
297 First Law of 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.
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
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297 questions · page 11 of 15
- A. Isobaric
- B. Isothermal
- C. Adiabatic
- D. Both B and C
Explanation: The correct answer is Adiabatic. Sound waves propagate through air by compressing and rarefying air molecules.
Correct answer: Adiabatic- A. Isotherm
- B. Both "A" and "C"
- C. Adiabatic
- D. Either "A" or "C"
Explanation: An isothermal process is a thermodynamic process that occurs at a constant temperature.
Correct answer: Isotherm- A. Escape of air from a burst tire
- B. Cloud formation
- C. Slow expansion
- D. None
Explanation: The correct answer is Slow expansion, as it allows heat transfer with the surroundings due to the extended time over which it occurs.
Correct answer: Slow expansion- A. 1PV
- B. 2PV
- C. PV/2
- D. 0
Explanation: The total work done is given by the area under the graph which in this case is a parallelogram.
Correct answer: 1PV- A. Work done by the system
- B. Work done on the system
- C. Increase in internal energy
- D. Increase in temperature
Explanation: In an isothermal process, the heat energy added to a system results in work done by the system.
Correct answer: Work done by the system- A. ∆U-W
- B. Q-W
- C. P∆V
- D. Q+W
Explanation: The correct answer is Q-W according to the first law of thermodynamics, which defines the change in internal energy (∆U) as the heat added…
Correct answer: Q-W- A. 2.5 ergs
- B. 250J
- C. 300J
- D. 150J
Explanation: The work done by a gas during expansion can be calculated using the formula: Work = Pressure × Change in Volume Given: Pressure = 103 N/m²…
Correct answer: 250J- A. Zero
- B. -100J
- C. 200J
- D. 100J
Explanation: During adiabatic expansion, there is no exchange of heat between the system and its surroundings.
Correct answer: 100J- A. Work
- B. Pressure
- C. Change in internal energy
- D. None of these
Explanation: In the context of an ideal gas undergoing a process at constant temperature, the internal energy of the gas is only a function of its…
Correct answer: Change in internal energy- A. Free expansion
- B. Adiabatic expansion
- C. Isothermal expansion
- D. Isothermal compression
Explanation: The correct answer is Adiabatic expansion. In adiabatic expansion, there is no heat exchange with the surroundings, and the gas does work…
Correct answer: Adiabatic expansion- A. Does not depend on path
- B. Corresponds to isothermal process
- C. Depends on path
- D. Corresponds to adiabatic process
Explanation: The correct answer is that internal energy does not depend on path. This is because internal energy is a state function, which means it is…
Correct answer: Does not depend on path- A. The temperature will decrease
- B. The volume will increase
- C. The pressure will remain constant
- D. The temperature will increase
Explanation: If ∆W = 0 and ∆Q = -ve for an ideal gas, then the temperature of the gas will decrease.
Correct answer: The temperature will decrease- A. 100J
- B. +50J
- C. -100J
- D. -50J
Explanation: In an adiabatic process, there is no exchange of heat with the surroundings (Q = 0).
Correct answer: 100J- A. 24/5
- B. 40/3
- C. 8
- D. 32 times its initial pressure
Explanation: In an adiabatic process for a monoatomic gas, the relation PVγ = constant applies, where γ (gamma) is the adiabatic index, which is 5/3…
Correct answer: 32 times its initial pressure- A. Must remain the same
- B. May fall
- C. May rise
- D. Both B & C
Explanation: If heat neither enters nor leaves a system, then its temperature may rise or may fall.
Correct answer: Both B & C- A. Isochoric process
- B. Isobaric process
- C. Adiabatic process
- D. Isothermal process
Explanation: The correct answer is the isothermal process. In this process, the temperature of the system remains constant, which means there is no…
Correct answer: Isothermal process- A. Working of bicycle pump
- B. Brakes applied by an automobile
- C. Human metabolism
- D. All of the above
Explanation: Human metabolism, brakes applied by an automobile and working of bicycle pump are all examples of first law of thermodynamics.
Correct answer: All of the above- A. A
- B. B
- C. C
- D. D
Explanation: As the gas expands, W is negative, also ∆U decreases and gas expand. There is no heat supplied to the system.
Correct answer: B- A. -600J
- B. 0J
- C. 200J
- D. -200J
Explanation: W = ∆P∆V = 1x105x2x10-3 = 2x102 = 200J W=positive because work done by yz path is more than xw path
Correct answer: 200J- A. To do external work
- B. Internal energy of the gas increases
- C. Both 'A' and 'B'
- D. None of these
Explanation: lsochoric process. When heat is added at constant volume (an isochoric process), it primarily increases the internal energy of the system…
Correct answer: Internal energy of the gas increases