In NH4NO2, there are two parts: the ammonium ion NH4+ and the nitrite ion NO2- . We will find the oxidation state of nitrogen in each part separately.1. In the ammonium ion NH4+ :Since hydrogen has an oxidation state of +1, and there are four hydrogen atoms, the total positive charge from hydrogen is +4. The ammonium ion has a net charge of +1. Therefore, the oxidation state of nitrogen N in NH4+ is -3 to balance the charge.2. In the nitrite ion NO2- :Oxygen has an oxidation state of -2, and there are two oxygen atoms, so the total negative charge from oxygen is -4. The nitrite ion has a net charge of -1. Therefore, the oxidation state of nitrogen N in NO2- is +3 to balance the charge.So, in NH4NO2, the oxidation states of nitrogen are -3 in the ammonium ion and +3 in the nitrite ion.