N-IIIH3 + 9 KOH + 4 Cl20 8 KCl-I + KNVO3 + 6 H2O

This is an oxidation-reduction (redox) reaction:

8 Cl0 + 8 e- 8 Cl-I (reduction)

N-III - 8 e- NV (oxidation)

Change the oxidation states