JEE Main levelNumerical answerDifficulty 2 of 3td180
Two moles of a monatomic ideal gas at 400K expand adiabatically and reversibly, doing 3.0kJ of work on the surroundings. Taking R=8.314Jmol−1K−1, find the final temperature in K (nearest integer).
Numerical answer type, answer in K, tolerance 1.
Answer: 280 K
With q=0, ΔU=w=−3000J=nCVΔT=2×1.5×8.314ΔT. So ΔT=−120.28K and T2=400−120.28=279.7K, about 280 K.