Give reason for the following:

The blue colour of aqueous copper sulphate fades when it is electrolyzed using platinum electrodes.

The blue colour of CuSO₄ solution is due to the Cu²⁺ ions. During it's electrolysis using Pt electrodes, at the cathode Cu²⁺ ions are discharged as neutral copper atoms by accepting electrons. These are not replaced by Cu²⁺ ions from the anode because at the anode, OH^- ions are discharged. As Cu²⁺ ions decrease, the blue colour of CuSO₄ solution fades and it becomes almost colourless as soon as Cu²⁺ ions are finished.