A system consists of two phases maintained at constant temperature (T) and pressure (p). The number of moles present in phase 1 and phase 2 of the system is represented by n i (where i = 1,2) and Gibbs free energy per mole of phase i at this temperature and pressure is $$g_{i}$$ (T,p). The necessary condition for equilibrium:

A

$$g_{1} (T,p) > g_{2} (T ,p)$$

B

$$g_{1} (T,p ) = g_{2} (T ,p)$$

C

$$g_{1} (T,p ) <g_{2} (T ,p)$$

D

$$g_{1} (T,p ) =-g_{2} (T ,p)$$