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.