Question

The oxidation number of $Fe$ in ${Na}_2\left[Fe{\left(CN\right)}_{5}NO\right]$ is :

• A. 2
• B. 1
• C. 3
• D. -2

Answer 1

The correct option is A 2

The oxidation number of $Fe$ in ${Na}_2\left[Fe{\left(CN\right)}_{5}NO\right]$ is calculated as follows:

${Na}_2\left[Fe{\left(CN\right)}_{5}NO\right]⟶2N{a}^{+}+$ [Fe$(CN{)}_{5}NO{]}^{-2}$

Now, to determine the O.S. of $Fe$ in $\left[Fe\right(CN{)}_{5}NO{]}^{-2}$, let O.S. of $Fe=x$.

So, $x+(-1)5+0+1=-2$

$x-5+1=2$
$x=+2$

As cyanide has $-1$ charge and $NO$ has $+1$ charge.