Question

Find the oxidation number of carbon in HCOOH.

Answer 1

Let the oxidation number of $C$ be $x$

The oxidation number of $O$ & $H$ are $-2$ & $+1$ respectively.

$\therefore +1+x-2-2+1=0$

$\therefore x-2=0$

Therefore, the oxidation number of $C$ in $HCOOH$ is $+2$.