Which one of the following electrolytes show a change in concentration but no change in chemical composition when electrolysis is carried out using inert electrodes ?

During the electrolysis of aqueous KNO₃ using inert electrodes,

Oxygen is liberated at anode.

$2{\mathrm{H}}_2\mathrm{O}\to 4{\mathrm{H}}^{+}+{\mathrm{O}}_2+4{\mathrm{e}}^{-}$

Hydrogen is liberated at cathode.

$[2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}\to {\mathrm{H}}_2+2{\mathrm{OH}}^{-}]\times 2$

Thus [KNO₃] increases but composition does not change.