Question: 66: One mole of an ideal gas at 300 K is expanded isothermally from 1 L to 10 L volume. \Delta \mathrm{U} for this process is
(Use \mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} )
(1) 1260 J
(2) 2520 J
(3) 5040 J
(4) 0 J
Answer: Option (4)
Explanation:
For an ideal gas, internal energy depends only on temperature.
In an isothermal process, temperature remains constant throughout the process.
Since the initial and final temperatures are the same, the change in internal energy is zero.
Mathematically, for an ideal gas:
\Delta \mathrm{U} = 0Hence, during isothermal expansion of an ideal gas, the internal energy does not change.
Therefore, \Delta \mathrm{U} for this process is 0 J.
Hence, option (4) is correct.