Question
Which of the following is the correct expression of the first law of thermodynamics for adiabatic processes ?
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (18 April Shift 2)
MHT CET Chemistry Question (2026) — Solution
Options
- A. W = -Q
- B. - U = -W
- C. U = QV
- D. U = Q_P - P_ ext \, V
Answer
B. - U = -W
Step-by-step solution
According to the first law of thermodynamics, the change in internal energy is given by U = Q + W. For an adiabatic process, there is no heat exchange between the system and the surroundings, which means Q = 0. Substituting Q = 0 into the first law equation, we get U = W. Multiplying both sides by -1, this can be written as - U = -W. Answer: - U = -W
Related: Chemistry — Thermodynamics (C) · All PYQ Banks