The oxidation number of $P$ in $KH_2PO_2$ is:

One mole of $N_2H_4$ loses $10 \ moles$ of electrons to form a new compound $Z$. Assuming that all the nitrogen atoms appear in the new compound, what is the oxidation state of nitrogen in $Z$? (There is no change in the oxidation state of hydrogen.)

Calculate the oxidation number of nitrogen and chlorine in $NOClO_4$.

The characteristic oxidation number of atoms in free metals is

In the conversion $Br_2 \to BrO_3^-$,the oxidation state of bromine changes from

The oxidation number of hydrogen in $LiH$ is