Question

$C{N}^{-}$ resembles $C{l}^{-},B{r}^{-}$ and $I^{-}$ in many of its properties. It is known as pseudohalide. Choose correct statements for pseudohalides :

• A. $C{N}^{-}$ can form HCN.
• B. $C{N}^{-}$ can be oxidised to cyanogen.
• C. $C{N}^{-}$ can't be oxidised to $C{N}_2$.
• D. $C{N}^{-}$ forms insoluble salts with $A{g}^{+},P{b}^{2+}andH{g}_2^{2+}$.
• E. $N_3^{-}$ is a pseudohalide.

Answer 1

Answer: (A), (B), (D), (E)

The correct options are
A $C{N}^{-}$ can form HCN.
B $C{N}^{-}$ can be oxidised to cyanogen.
D $C{N}^{-}$ forms insoluble salts with $A{g}^{+},P{b}^{2+}andH{g}_2^{2+}$.
E $N_3^{-}$ is a pseudohalide.

$C{N}^{-}$ is called pseudohalide. Like $X^{-}$
- it forms HCN
- it can be oxidised to $(CN{)}_2$
- it forms insoluble salts with $A{g}^{+},P{b}^{2+}andH{g}_2^{2+}$
Other pseudohalides are :

$SC{N}^{-}\left(thiocyanate\right),OC{N}^{-}\left(cyanate\right),NC{N}^{2-}\left(cyanamide\right)$,

$SeC{N}^{-}\left(selenocyanate\right),ON{C}^{-}\left(fulminate\right),N_3^{-}\left(azide\right)$