2 NaNO2 (aq) + 2 NaI (aq) + 2 H2SO4 (aq) → 2 Na2SO4 (aq) + I2 (s) + 2 NO (g) + 2 H2O (l)
This is an oxidation-reduction (redox) reaction:
2 I-I - 2 e- → 2 I0 (oxidation)
2 NIII + 2 e- → 2 NII (reduction)
NaI is a reducing agent, NaNO2 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.