Question
Which from following is correct expression of first law of thermodynamics for isothermal process?
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (18 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. W = - Q
- B. - U = - W
- C. U = Q _ v
- D. Q _ p = U + P _ ext V
Answer
A. W = - Q
Step-by-step solution
According to the first law of thermodynamics, the change in internal energy is given by U = Q + W. For an isothermal process, the temperature of the system remains constant, so T = 0. Since the internal energy of an ideal gas depends only on temperature, the change in internal energy is zero, U = 0. Substituting U = 0 into the first law equation gives: 0 = Q + W W = -Q Answer: W = - Q
Related: Chemistry — Thermodynamics (C) · All PYQ Banks