Assertion: In the electrolysis of aqueous NaCl using Pt electrodes,  $C{l}^{-}$  ions oxidizing instead of H₂O molecules.

Reason: Over voltage is required for the decomposition of  ${\text{H}}_{\text{2}}{\text{O to O}}_{\text{2}}$       

When the potential difference is established across the solution, Na⁺ and H⁺ ions move toward the cathode and Cl^-
and OH- ions move towards the anode. 

Discharge potential: $O{H}^{-}>C{l}^{-}$

The lower value of E_cell this preferred, but due to overvoltage chlorine is liberated at anode.