The point of intersection and sudden increase in the slope, in the diagram given below, respectively, indicates :
(1) ΔG = 0 and melting or boiling point of the metal oxide
(2) ΔG > 0 and decomposition of the metal oxide
(3) ΔG < 0 and decomposition of the metal oxide
(4) ΔG = 0 and reduction of the metal oxide