In which compound is the oxidation state of nitrogen $-1$?

$KMnO_4$ acts as an oxidising agent in the neutral medium and gets reduced to $MnO_2$. What is the equivalent weight of $KMnO_4$ in a neutral medium?

The oxidation state of phosphorus in hypophosphoric acid is $+......$

What is the correct order of oxidation states of sulfur in the following anions: $SO_3^{2-}$,$S_2O_4^{2-}$,and $S_2O_6^{2-}$?

Give the rules for the calculation of oxidation number.

Find out the oxidation number of chlorine in the following compounds and arrange them in increasing order of oxidation number of chlorine.
$NaClO_4, NaClO_3, NaClO, KClO_2, Cl_2O_7, ClO_3, Cl_2O, NaCl, Cl_2, ClO_2$.
Which oxidation state is not present in any of the above compounds?