NaIVO3 + 5 NaI-I + 3 H2SO4 3 Na2SO4 + 3 I20 + 3 H2O

This is an oxidation-reduction (redox) reaction:

5 I-I - 5 e- 5 I0 (oxidation)

IV + 5 e- I0 (reduction)

Change the oxidation states