We have to balance the given redox reaction and find out the oxidizing and reducing agent.
I2(s) + OCl-(aq) → IO3-(aq) + Cl-(aq) (acidic solution)
A redox reaction can be balanced (in acidic solution) by these steps:
Step 1: Separate the whole reaction into two half-reactions.
Step 2: Balance the non-hydrogen and non-oxygen elements first.
Step 3: Balance oxygen by adding H2O to the side that needs oxygen. (1 O: 1 H2O)
Step 4: Balance hydrogen by adding H+ to the side that needs hydrogen. (1 H: 1 H+)