JEE Main levelSingle correct optionDifficulty 2 of 3td181
One mole of a monatomic ideal gas at 300K doubles its volume, once by a reversible isothermal path and once by a reversible adiabatic path. The ratio ∣wadiabatic∣/∣wisothermal∣ is nearest to
A0.80
B1.25
C0.50
D1.00
Answer: A
Isothermal: ∣w∣=RTln2=1729J. Adiabatic: T2=300×2−2/3=189.0K and ∣w∣=1.5R(300−T2)=1384J. The ratio is 0.80; the adiabatic work is smaller because the gas cools as it expands.