Question

Determine oxidation number of iron in $N{a}_2\left[Fe\right(CN{)}_5\left(NO\right)]$.

• A. + 2
• B. 3
• C. 1
• D. 4

Answer 1

The correct option is B 3

$CN$ has a charge of $-1$, $NO$ is $0$, and $Na$ is $+1$. This makes $Fe+3$, since it has to combine with the overall $+2$ from the sodium ions to balance the overall $-5$ from the cyanide groups.

$2\times (+1)+x+5\times (-1)+0=0$
$x=+3$
Option B is correct.