4 H2SO4 (aq) + 2 NaNO3 (aq) + 6 NaI (aq) → 4 H2O (l) + 2 NO (g) + 3 I2 (s) + 4 Na2SO4 (aq)
This is an oxidation-reduction (redox) reaction:
6 I-I - 6 e- → 6 I0 (oxidation)
2 NV + 6 e- → 2 NII (reduction)
NaI is a reducing agent, NaNO3 is an oxidizing agent.
This is a precipitation reaction: I2 is the formed precipitate.
This is a gas evolution reaction, NO is the formed gas.