The correct option is D pH remains constant
Electrolysis of dilute NaCl (aq) carried out using inert electrodes:
Since ,
E0H2O/H2>E0Na+/Na
Reaction at cathode:
2H2O(l)+2e−⇌H2(g)+2OH−(aq)
Reaction at anode: If concentration of Cl− is low, oxidation of H2O to give O2 is favoured.
2H2O(l)⇌4H+(aq)+O2(g)+4e−
For the same number of electrons transferred, both H+ and OH− ions produced, neutralise each other.
Hence pH remains constant during electrolysis of dilute NaCl (aq) using inert electrode.