the answer is: Cl was reduced in this reaction according to the balanced reaction equation, we can know that: - as Cl in OCl^- is +1 and Cl in Cl^- is -1 - and Cr in CrO4^-2 is +6 - and Cr in Cr(OH)3 is +3 ∴ Cl went from +1 to -1 and was reduced, It means a reduction in charge. & Cr went from +3 to +6 so it was oxidized.