Region of the solution near an electrode becomes alkaline during electrolysis of aqueous `Na_(2)SO_(4)` solution. State whether the electrode is anode or cathode.

Explanation

During electrolysis of aqueous `Na_(2)SO_(4)` solution, `Na^(+)(aq), SO_(4)^(2-)(aq) and H_(2)O(l)` are present.
Since standard reduction potential `(E^(@))` of `H_(2)O` is longer than that of `Na^(+), H_(2)O` instead of `Na^(+)`, will undergo reduction at the cathode. At the anode, `H_(2)O`, instead of `SO_(4)^(2-)`, will undergo oxidation since `E^(@)` of `H_(2)O` is smaller than that of `SO_(4)^(2-)`.
`"Cathode reaction :"2H_(2)O(l)+2e rarr 2OH^(-)(aq)+H_(2)(g)`
`"Anode reaction : "H_(2)O(l)rarr 2H(+)(aq)+(1)/(2)O_(2)(g)+2e`
Because of the formation of `OH^(-)` ions, the solution in the cathode compartment becomes alkaline. So, the electrode is cathode.