Following are some standard Gibbs energies of formation, f G, at 1000 K: NiO(s), -115 kJ

Following are some standard Gibbs energies of formation, Δ_fG°, at 1000 K: NiO(s), -115 kJ mol^-1; MnO(s), -280 kJ mol^-1; TiO₂(s), -630 kJ mol^-1. The standard Gibbs energy of formation of CO(g) at 1000 K is -250 kJ mol^-1. Use the method of coupled reactions to determine which of these metal oxides can be reduced to the metal by a spontaneous reaction with carbon at 1000 K and with all reactants and products in their standard states.