Question

Which of the following are the white precipitate and the soluble substance formed by the excess of the KCN reagent, respectively in (iv)?

• A. $As\left(CN{)}_{3}and\right[As(CN{)}_6{]}^{3-}$
• B. $Sb\left(CN{)}_{3}and\right[Sb(CN{)}_6{]}^{3-}$
• C. $Zn\left(CN{)}_{2}and\right[Zn(CN{)}_4{]}^{2-}$
• D. $Cd\left(CN{)}_{2}and\right[Cd\left(CN{)}_4^{2-}\right]$

Answer 1

The correct option is D $Cd\left(CN{)}_{2}and\right[Cd\left(CN{)}_4^{2-}\right]$

Here compound contains $C{d}^{2+}$ as a cation which reacts with KCN and form

$C{d}^{2+}+KCN\to Cd(CN{)}_2\to Cd(CN{)}_4^{-2}$