2 NaIO3 (aq) + 5 CO (g) + H2SO4 (aq) → Na2SO4 (aq) + I2 (s) + 5 CO2 (g) + H2O (l)
This is an oxidation-reduction (redox) reaction:
5 CII - 10 e- → 5 CIV (oxidation)
2 IV + 10 e- → 2 I0 (reduction)
CO is a reducing agent, NaIO3 is an oxidizing agent.