3 H2O2 + 2 Cr(OH)3 + 4 KOH → 2 K2CrO4 + 8 H2O
This is an acid-base reaction (neutralization): Cr(OH)3 is an acid, KOH is a base.
This is an oxidation-reduction (redox) reaction:
6 O-I + 6 e- → 6 O-II (reduction)
2 CrIII - 6 e- → 2 CrVI (oxidation)
H2O2 is an oxidizing agent, Cr(OH)3 is a reducing agent.