Question

Blue solution of $CuS{O}_4$ when reacts with excess of $KCN$ gives colourless solution due to the :

• A. formation of $CuCN$
• B. formation of $Cu(OH{)}_2$
• C. formation of $\left[Cu\right(CN{)}_4{]}^{2-}$
• D. $C{u}^{2+}$ is reduced by $C{N}^{-}$ to $C{u}^{+}$ which forms complex $\left[Cu\right(CN{)}_4{]}^{3-}$

Answer 1

Answer: (C)

formation of $\left[Cu\right(CN{)}_4{]}^{2-}$

Reaction of process:
$CuS{O}_4\stackrel{KCN}{\to }\left[Cu\right(CN{)}_4{]}^{-2}$ colourless
Blue colour