2 HI-I + 2 KNIIIO2 + H2SO4 I20 + 2 NIIO + K2SO4 + 2 H2O

This is an oxidation-reduction (redox) reaction:

2 I-I - 2 e- 2 I0 (oxidation)

2 NIII + 2 e- 2 NII (reduction)

Change the oxidation states