Using the law of mass action, write the equilibrium expression for each of the followi ng reactions .(a) 8H2(g) + S8(s)↔8H2S(g), (b) C(s) + H2O(l) + Cl2(g) ↔COCl2(g) + H2(g), (c) CaCO3(s) ↔CaO(s) + CO2(g), (d) 3 C2H2(g) ↔ C6H6(l)