Na2HPO4
KOH
K4[Fe(CN)6]
K2CrO4
[NiCl4]2−TetrahedralHCl(Q)⇌excessNi2+(M1)KCN(R)→excess[Ni(CN)4]2−squareplanar[ZnCl4]2−TetrahedralHCl(Q)⇌excessZn2+(M2)KCN(R)→excess[Zn(OH)4]2−Tetrahedral↓KOH(S)Zn(OH)2Whiteppt.KOH→excess[Zn(OH)4]2−Soluble