In which among the following compounds,the oxidation number of nitrogen is $ +5 $?

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.)

Identify the oxidation number of Sulphur in $SO_2$ and $SO_4^{2-}$ respectively.

The oxidation number of $As$ in $H_2AsO_4^-$ is:

If a metal ion $M^{3+}$ loses three more electrons,what will be its final oxidation number?

Select the compound in which chlorine is assigned the oxidation number $+5$.