The point of intersection and sudden increase in the slope, in the diagram given below respectively, indicates:

At the point of intersection3Mg+Al2O3⇌3MgO+2Al  ΔG=0 (Equilibrium)Sudden increase indicates change of physical state from solid to liquid (M.P) (or) liquid to Vapour (B.P)[Note : actually sudden increase in slope is due to change in physical state of metal, not due to change in physical state of metal oxide. But among the given option-1 is best choice.]