Write correctly balanced half reaction and the overall equations for the skeleton equation:
          

1. Write the oxidation and reduction half-reactions by observing the changes in oxidation number and write these separately.
                                        +3            +4 
Oxidation half reaction:        

Reduction half reaction:     +7                +2
                                      
2. Balancing the oxidation half reaction.
 (i) Balance C atoms by multiplying CO₂ by 2.
                   +3                     +4
                    
(ii) Add 2 electrons towards R.H.S. in order to balance charges on carbon atoms.
                   
(iii) Balance H atoms by adding two H⁺ (reaction occurs in the acidic medium) towards R.H.S.

3. Balancing the reduction half reaction.
   (i) Balancing of Mn is not required as the number of each Mn is one on both the sides.
                   +7
                  
(ii) Add 5 electrons towards L.H.S. in order to balance the charges on manganese atoms. 
                       
(iii) Balance H atoms by adding eight H⁺ towards
L.H.S.
        
                                      (Balanced reduction half reaction)
4. Multiply balanced oxidation half reaction by 5 and balanced reduction half reaction by 2 to equate the electrons and add both the half reactions.