SnS + 5 H2O2 + 4 NaOH → Na2SnO3 + Na2SO4 + 7 H2O
This is an oxidation-reduction (redox) reaction:
S-II - 8 e- → SVI (oxidation)
SnII - 2 e- → SnIV (oxidation)
10 O-I + 10 e- → 10 O-II (reduction)
SnS is a reducing agent, SnS is a reducing agent, H2O2 is an oxidizing agent.