Question
A gas absorbs 120 J of heat and expands by 300 10^ -6 \ m ^3 against a constant external pressure of 2 10^5\ Nm ^ -2 . What will be the change in internal energy of the system ?
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (19 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. 180 J
- B. 240 J
- C. 120 J
- D. 60 J
Answer
D. 60 J
Step-by-step solution
Heat absorbed by the gas, q = +120\ J Work done by the gas during expansion against constant external pressure is given by W = -P_ ext V Substituting the given values: W = -(2 10^5\ Nm ^ -2 ) (300 10^ -6 \ m ^3) W = -60\ J According to the first law of thermodynamics: U = q + W U = 120\ J - 60\ J = 60\ J
Related: Chemistry — Thermodynamics (C) · All PYQ Banks