NH4NO3 is composed of two ions: the ammonium ion NH4+ and the nitrate ion NO3- . To determine the oxidation state of the nitrogen atom in NH4NO3, we need to find the oxidation state of nitrogen in both ions separately.In the ammonium ion NH4+ , nitrogen is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Therefore, the total oxidation state of the four hydrogen atoms is +4. Since the ammonium ion has a charge of +1, the nitrogen atom must have an oxidation state of -3 to balance the charge.In the nitrate ion NO3- , nitrogen is bonded to three oxygen atoms. Oxygen has an oxidation state of -2. Therefore, the total oxidation state of the three oxygen atoms is -6. Since the nitrate ion has a charge of -1, the nitrogen atom must have an oxidation state of +5 to balance the charge.So, in the compound NH4NO3, the nitrogen atom has two different oxidation states: -3 in the ammonium ion and +5 in the nitrate ion.