CHEMISTRY · Single correct · ISC · Chemistry · Equilibrium · Common ion effect
Problem
A solution of a metal ion, when treated with KI, gives a red precipitate which dissolves in an excess of KI to give a colourless solution. Moreover, the solution of the metal ion on treatment with a solution of cobalt (II) thiocyanate gives rise to a deep blue crystalline precipitate. The metal ions is:
(1) Pb2+
(2) Hg2+
(3) Cu2+
(4) Co2+