Which quantity out of `Delta_(r) G and Delta_(r) G^( Theta )` will be zero at equilibrium ?

Explanation

Gibbs energy for a reaction in which all reactants and products are in standard state.
`Delta_(r) G^( Theta )` is related to the equilibrium constant of the reaction as follows :
`Delta_(r) G= Delta_(r) G^( Theta ) + "RT In k"`
At equilibrium, `0= Delta_(r) G^( Theta ) + "RT In k" (because Delta_(r) G= 0)`
OR
`Delta_(r) G^( Theta ) = - "RT In k"`
`Delta_(r) G^( Theta ) = 0 "when" K=1`
For all other values of `K, Delta_(r) G^( Theta )` will be non-zero.