Question

43
4
40. In the separation of Cu2+ and Cd2+ of IInd
group in qualitative analysis of cations,
tetrammine copper (II) sulphate and
tetrammine cadmium (II) sulphate react
with KCN to form the corresponding cyano
complexes, which one of the following pairs
of the complexes and their relative stability
enables the separation of Cu2+ and Cd2+?
[2000]
(a) K3 [Cu(CN),]: less stable and
K [Cd(CN),]: more stable
(b) K3 [Cu(CN),]: more stable and
K [Cd(CN),]: less stable
(C) K2[Cu(CN),]: less stable and
K2 [Cd(CN),]: more stable
(d) K2 [Cu(CN),]: more stable and
K [Cd(CN)]: less stable​

Answer 1

the answer    is

(b) K3 [Cu(CN),]: more stable and

K [Cd(CN),]: less stable