When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is

Answer: Option C

If the liquid and vapor are pure, in that they consist of only one molecular component and no impurities, then the equilibrium state between the two phases is described by the following equations:
P_liq = p_vap, T_LIQ = T_VAP, G_LIQ = G_VAP.