2 HNVO3-II + I20 + 2 O20 2 HIVO3-II + 2 NIVO2-II

This is an oxidation-reduction (redox) reaction:

2 I0 - 10 e- 2 IV (oxidation)

2 NV + 2 e- 2 NIV (reduction)

4 O0 + 8 e- 4 O-II (reduction)

Change the oxidation states