(b) The melting points of metals A and B are and respectively. They form an intermetallic compound C, containing 75 percent of A which melts at. Mixtures containing 20 percent and 90 percent of A melt at constant temperatures at and respectively. marks] marks] mark] (i) Draw an approximate equilibrium diagram and label each area to indicate the equilibrium involved. [4 Explain what happens on cooling liquid mixture containing 50% of A. [1 (111) Describe the effect of melting a mixture of zinc in a lead - silver alloy. [