The oxidation number of $S$ in $Na_2S_4O_6$ is ...........

What is the oxidation number of $Fe$ in $Fe_3O_4$?

In the following reaction,assign the correct category for the underlined atom based on the product of complete hydrolysis at $R.T.$:
$\underline{S}O_2Cl_2 + H_2O \longrightarrow H_2SO_4 + HCl$

Iodine reacts with concentrated $HNO_3$ to yield $Y$ along with other products. The oxidation state of iodine in $Y$ is

The oxidation number of $C$ in $CO_2$ is

Carbon has zero oxidation number in