Balance the following equation in basic medium by ion-electron method and oxidation number method and identify the oxidising agent and the reducing agent.

(A) Ion-electron method: 
1. Write the oxidation and reduction half-reaction by observing the changes in oxidation numbers.
Oxidiation half reaction:
        -1                      0
   
Reduction half-reaction:
       +7                  +3
      
2. Balancing the oxidation half reaction
    (i) Add 2 electrons towards R.H.S. to balance the charges
                
   (ii) Add 2 OH^- ions towards L.H.S to balance the charges
         
(iii) Balance O atoms by adding two H₂O molecules towards H
          
3. Balancing the reduction half reaction
   
  
 4. Multiply balanced oxidation half-reaction by 4 and add it to the balanced reduction half-reaction.

(B) Oxidation number method            
 (i) The skeleton equation along with oxidation number of each atom is
+7 -2          +1 -1                 +3               0

(ii) The ON of O atom increases by 1 per atom while that of CI decreases by 4 per atom.

Thus Cl₂O₇(g) acts as an oxidising agent while H₂O₂(aq) as the reducing agent
Total increase in O.N. of H₂O₂ = 2 X 1=2
Total decrease in O.N. of Cl₂O₇ = 4 x 2 = 8
(iii) Equalise the increase/decrease in O.N. by multiplying H₂O₂ and O₂ by 4.

(iv) Balance Cl atoms by multiplying 
    
(v) Balance O atoms by adding three  towards R.H.S.
           
(vi) Balance H atoms by adding two  towards R.H.S. and two OH^- towards L.H.S.

This is the balanced redox equation.