Question

Oxidation number of cobalt in $K\left[Co{\left(CO\right)}_4\right]$ is:

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

Answer 1

The correct option is C $-1$

Let oxidation number of $Co$ be $x$ and $CO$ has zero oxidation number. The oxidation number of $K$ is +1.

So, $1+x=0$.

$x=-1$.

The oxidation number of cobalt is -1.