The sum of the oxidation numbers of all atoms in the $S_{2}O_{3}^{2-}$ ion is:

The oxidation state of $Cr$ in $Cr_2O_7^{2-}$ is

What is the oxidation state of oxygen in $OF_2$?

What is the difference in oxidation number of $Mn$ in $KMnO_4$ and $MnO_2$?

Which one of the following reactions does not involve either oxidation or reduction?

$1 \ mol$ of compound $N_2H_4$ loses $10 \ mol$ of electrons to form a new compound $Y$. Assuming all nitrogen atoms are present in compound $Y$,what is the oxidation state of $N$ in compound $Y$?