Assuming that water vapour is an ideal gas, the internal energy change ($\Delta U$) when 1 mole of water is vapourised at 1 bar pressure and $100^{\circ}C$, (Given : molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ mol$^{-1}$ and R = 8.3 J mol$^{-1}$ K$^{-1}$ ) will be :

Question

( A ) $3.7904 \; kJ\; mol^{-1}$
( B ) $4.100\; kJ\; mol^{-1}$
( C ) $41.00\; kJ\; mol^{-1}$
( D ) $37.904 \; kJ\;mol^{-1}$