Assertion : For a reversible reaction, Gibbs’ free energy is zero at equilibrium. Reason : As reaction approaches equilibrium, Gibbs’ free energy decreases.

The standard Gibb's energy for a reaction is given by ΔG. At equilibrium, ΔG = 0 whereas, ° ΔG For a reaction may or may not be zero. For a spontaneous process, Gibb's energy for a reaction is always negative, ΔG <0 . Hence, Assertion is false but Reason is true.