Unit mass of a liquid with volume \[{{V}_{1}}\] is completely changed into a gas of volume \[{{V}_{2}}\] at a constant external pressure P and temperature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is [Roorkee 1999]

• A.            Zero                                         
• B.            \[P({{V}_{2}}-{{V}_{1}})\]
• C.            \[L-P({{V}_{2}}-{{V}_{1}})\]   
• D.            L