When dealing with redox reactions of halogens, remember the trend of oxidizing power: F₂>Cl₂>Br₂>I₂. A halogen can oxidize the halide ions below it in the group. Chlorine can oxidize Br⁻ and I⁻, but the extent of oxidation of iodine to oxoacids is usually up to the +5 state (iodic acid), not the +7 state.