Na2SO4 + 4 C → Na2 + S + 4 CO
This is an oxidation-reduction (redox) reaction:
2 NaI + 2 e- → 2 Na0 (reduction)
SVI + 6 e- → S0 (reduction)
4 C0 - 8 e- → 4 CII (oxidation)
Na2SO4 is an oxidizing agent, Na2SO4 is an oxidizing agent, C is a reducing agent.
Warning: Unknown compound 'Na2'