Question

Oxidation state of central atom in $Ni(CN{)}_4^{2-}$ is :

• A. $-2$
• B. $0$
• C. $+2$
• D. $+4$

Answer 1

The correct option is C $+2$

Let $x$ be the oxidation state of nickel in $Ni(CN{)}_4^{-2}$.
The oxidation state of cyanide group is $-1$.
The sum of the oxidation states is equal to $-2$ which is the charge on the ion.
Therefore $x+4(-1)=-2$ or, $x=+2$
Hence, the oxidation state is $+2$.