Balance the equation by half reaction method:

1. Write the oxidation and reduction half-reactions by observing the changes in oxidation numbers and write these separately.
                                                 0       +5
Oxidation half-reaction:                  
                                              0
Reduction half-reaction:               
2.  Balancing the oxidation half reaction.
(i) Balance 1 atoms by multiplying   by 2.
                          0       +5
                          
(ii) Add 10 electrons towards R.H.S. to balance the charges on iodine atoms,
                            0         +5
                           
(iii) Since the medium is alkaline, 6H₂O molecules are added towards R.H.S. and 12 OH^-ions towards L.H.S. in order to balance oxygen and hydrogen atoms.
                       
3. Balancing the reduction half reaction. 
 (i) Balancing 1 atoms by multiplying I^- by 
2.                     0       +5
                     
(ii) Add two electrons towards L.H.S. in order to balance the charges on iodine atoms
                     
4. Multiplying reduction half-reaction by 5 to equate the electrons and add both the half reactions.

This is a balanced redox reaction.