3 Na2SO3 (aq) + K2Cr2O7 (aq) + H2SO4 (aq) → 3 Na2SO4 (aq) + Cr2O3 (s) + K2SO4 (aq) + H2O (l)
This is an acid-base reaction (neutralization): Na2SO3 is a base, H2SO4 is an acid.
This is an oxidation-reduction (redox) reaction:
3 SIV - 6 e- → 3 SVI (oxidation)
2 CrVI + 6 e- → 2 CrIII (reduction)
Na2SO3 is a reducing agent, K2Cr2O7 is an oxidizing agent.
This is a precipitation reaction: Cr2O3 is the formed precipitate.