The oxidation number of $Mn$ in $MnO_4^{-}$ is

Oxidation number of Nitrogen in $NH_4NO_3$ is

In thiosulphuric acid $(H_2S_2O_3)$,which of the following statements is correct?

The oxidation states of $S$ in peroxodisulphuric acid $(H_{2}S_{2}O_{8})$ and sodium tetrathionate $(Na_{2}S_{4}O_{6})$ are respectively:

The oxidation state of $N$ in $HNO_4$ is

Fill in the blanks:
$(1)$ During the reaction $CN^{-} \to CNO^{-}$,......... is added.
$(2)$ The maximum positive oxidation number for any chalcogen compound may be ......... .