question_answer

In the separation of \[C{{u}^{2+}}\] and \[C{{d}^{2+}}\] in 2nd group 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 enable the separation of \[C{{u}^{2+}}\] and \[C{{d}^{2+?}}\]

A) \[{{K}_{3}}\left[ Cu{{\left( CN \right)}_{4}} \right]\] more stable and \[{{K}_{2}}[Cd{{(CN)}_{4}}]\] less stable

B) \[{{K}_{2}}\left[ Cu{{\left( CN \right)}_{4}} \right]\] less stable and \[{{K}_{2}}[Cd{{(CN)}_{4}}]\] more stable

C) \[{{K}_{2}}\left[ Cu{{\left( CN \right)}_{4}} \right]\] more stable and \[{{K}_{2}}[Cd{{(CN)}_{4}}]\] less stable

D)  \[{{K}_{3}}\left[ Cu{{\left( CN \right)}_{4}} \right]\]less stable and \[{{K}_{2}}[Cd{{(CN)}_{4}}]\] more stable