# What is this oxidation number of CH_3OH and CH_2O?

Given that oxidation number is an empirical concept; the oxidation number of $C$ in methanol is $- I I$; in formaldehyde it is $0$.
On the Pauling scale, we can quote the electronegativities of $C , H , \mathmr{and} O$ as $2.55 , 2.20 , 3.44$. The means that the oxidation number of $C$ in methane, $C {H}_{4}$, is $- I V$, and the oxidation number of $C$ in carbon dioxide, $C {O}_{2}$ is $+ I V$.
Note that the SUM of the oxidation numbers equals the charge on the ion. Thus the oxidation number of $C$ in $C {O}_{3}^{2 -}$ =+IV (i.e. -2=C_"ON"+3xx(-2)