Which of the following substances contains the highest oxidation number of NITROGEN atom?Ammonia.Ammonium nitrate.Ammonium chlorideNitrogen dioxide.Nitrogen.

The oxidation number of nitrogen in the given substances are:

1. Ammonia (NH3): The oxidation state of Nitrogen in ammonia is -3. Hydrogen usually has an oxidation state of +1, and since the molecule is neutral, Nitrogen must have an oxidation state of -3 to balance it out.

2. Ammonium nitrate (NH4NO3): This compound is made up of two ions: the ammonium ion (NH4+) and the nitrate ion (NO3-). In the ammonium ion, the oxidation state of Nitrogen is -3 (as in ammonia), and in the nitrate ion, the oxidation state of Nitrogen is +5.

3. Ammonium chloride (NH4Cl): The ammonium ion (NH4+) is present in this compound as well, so the oxidation state of Nitrogen is -3.

4. Nitrogen dioxide (NO2): In this compound, the oxidation state of Nitrogen is +4. Oxygen usually has an oxidation state of -2, and since the molecule is neutral, Nitrogen must have an oxidation state of +4 to balance it out.

5. Nitrogen (N2): In elemental form, the oxidation state of Nitrogen is 0.

Therefore, Nitrogen has the highest oxidation number in Ammonium nitrate.