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

Explanation

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