Question

The oxidation number of cobalt in $K[Co(CO)_4]$ is

• A. $+1$
• B. $+3$
• C. $-1$
• D. $-3$

Answer 1

Answer: (C)

$-1$

Answer 2

We know that $CO$ is a neutral ligand and $K$carries a charge of $+1.$ Therefore, the complex can be written as $K ^{+} [Co(CO)_4] ^{-}$ . Therefore, the oxidation number of $Co$ in the given complex is $-1.$ Hence, option (iii) is correct