# GATE2012-31

Consider a binary liquid mixture at constant temperature T and pressure P. If the enthalpy change of mixing, $\Delta$H = 5x${_1}$x${_2}$, where x${_1}$ and x${_2}$ are the mole fraction of species 1 and 2 respectively, and the entropy change of mixing $\Delta$S = -R[x${_1}$ Inx${_1}$ + x${_2}$ Inx${_2}$] (with R = 8.314 J/mol.K), then the minimum value of the Gibbs free energy change of mixing at 300K occur when
1. x${_1}$ = 0
2. x${_1}$ = 0.2
3. x${_1}$ = 0.4
4. x${_1}$ = 0.5