Calculation of oxidation number of nitrogen in ammonium nitrite `NH_(4)NO_(2)`

Explanation

This is an ionic compound containing `NH_(4)^(+) and NO_(2)^(-)`  ions.
The oxidation number of nitrogen in `NH_(4)^(+)` ion `= -3`
The oxidation number of nitrogen `NO_(2)^(-)` ion `= +3`
Thus, one atom of nitrogen in ammonium nitrite is in `-3` oxidation state, while the other nitrogen atom is in `+3` oxidation state.