Question

The oxidation state of Fe in [Fe(CN)$_6$]$^{-3}$ :

• A. +3
• B. +2
• C. +4
• D. -3

Hint:

Always equate the sum of oxidation states of the central metal and ligands to the total charge on the coordination sphere. CN is always -1.

Answer 1

The Correct Option is A

Let the oxidation state of Iron (Fe) be $x$.
The cyanide ligand (CN) has a charge of -1. There are 6 cyanide ions.
The overall charge on the complex ion is -3.
The equation for the sum of oxidation states is: $x + 6(-1) = -3$.
$x - 6 = -3 \implies x = +3$.
Therefore, the oxidation state of Fe is +3.