Question

In quantitative analysis of second group in laboratory, $H_{2}S$ gas is passed in acidic medium for precipitation. When $Cu^{2+}$ and $Cd^{2+}$ react with $KCN$, then for product true statement is

• A. $K_{2} [Cu (CN)_{4}]$ more soluble
• B. $K_{3} [Cd(CN)_{4}]$ less stable
• C. $K_{2} [Cd(CN)_{3}]$ more stable
• D. $K_3 [Cu (CN)_{2}]$ less stable

Answer 1

Answer: (D)

In $K_{3}[Cu(CN)_{2}]$ copper is in $+1$ oxidation state while in $K_{2}[Cd(CN)_{2}]$ cadmium is in $+2$ oxidation state. The more the oxidation state o f the central metal atom, the more is the stability of the complex.