1 \({\operatorname{Mg} _{\text{3}}}\;{{\text{N}}_{\text{2}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, - 3\)
2 \({\text{N}}{{\text{H}}_{\text{2}}}{\text{OH}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + 1\)
3 \({\left( {{{\text{N}}_{\text{2}}}{{\text{H}}_{\text{5}}}} \right)_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{ + 2}}\)
4 \(\left[ {{\text{Co}}{{\left( {{\text{N}}{{\text{H}}_{\text{3}}}} \right)}_{\text{5}}}{\text{Cl}}} \right]{\text{C}}{{\text{l}}_{\text{2}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{0}}\)
Explanation:
The oxidation number of nitrogen in different compounds area.
\({\text{a}}.{\mkern 1mu} {\mkern 1mu} {\operatorname{Mg} _{\text{3}}}\;{{\text{N}}_{\text{2}}}({\text{ - 3}})\)
\({\text{b}}.{\text{ N}}{{\text{H}}_{\text{2}}}{\text{OH}}({\text{ - 1}})\)
\({\text{c}}{\text{. }}{\left( {{{\text{N}}_{\text{2}}}{{\text{H}}_{\text{5}}}} \right)_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}({\text{ - 2}})\)
\({\text{d}}{\text{. }}\left[ {{\text{Co}}{{\left( {{\text{N}}{{\text{H}}_{\text{3}}}} \right)}_{\text{5}}}{\text{Cl}}} \right]{\text{C}}{{\text{l}}_{\text{2}}}({\text{ - 3}})\)