An ideal gas at pressure ' P ' and temperature ' T ' is enclosed in a vessel of volume 'V'. Some gas leaks through a hole from the vessel and the pressure of the enclosed gas falls to \(\mathrm{P}^{\prime}\). Assuming that the temperature of the gas remains constant during the leakage, the number of moles of the gas that have leaked is

1. A \(\frac{2 \mathrm{~V}}{\mathrm{RT}}\left(\mathrm{P}-\mathrm{P}^{\prime}\right)\)
2. B \(\frac{\mathrm{V}}{\mathrm{RT}}\left(\mathrm{P}-\mathrm{P}^{\prime}\right)\)
3. C \(\frac{\mathrm{v}}{\mathrm{RT}}\left(\mathrm{P}+\mathrm{P}^{\prime}\right)\)
4. D \(\frac{\mathrm{V}}{2 \mathrm{RT}}\left(\mathrm{P}+\mathrm{P}^{\prime}\right)\)