The oxidation number of carbon in ${CH}_{2}O$ is

• ${\mathrm{CH}}_2\mathrm{O}$ also called formaldehyde. It is a pungent smelling, colorless gas that is generally flammable in nature.

        Let the oxidation number of carbon be x.

The oxidation number of oxygen is $-2$ and that of hydrogen is $+1$.

                    $$\begin{gathered} \mathrm{x}+2\left(1\right)-2=0 \\ \Rightarrow \mathrm{x}=0 \end{gathered}$$

So, the oxidation number of carbon in ${\mathrm{CH}}_2\mathrm{O}$ is 0 .