Which one of the following reactions occurs at the anode in the Castner process of extracting sodium metal?

Which of the following pairs has easier reduction at the cathode?

$O_2$ gas will be evolved as a product of electrolysis of $:$
$(A)$ an aqueous solution of $AgNO_3$ using silver electrodes.
$(B)$ an aqueous solution of $AgNO_3$ using platinum electrodes.
$(C)$ a dilute solution of $H_2 SO_4$ using platinum electrodes.
$(D)$ a high concentration solution of $H_2 SO_4$ using platinum electrodes.
Choose the correct answer from the options given below $:$

In the industrial production of which of the following,molecular hydrogen is obtained as a byproduct?

Give the electrolytic reactions of molten $NaCl$ occurring at inert electrodes.

What will be the $pH$ of the aqueous solution of the electrolyte in an electrolytic cell during the electrolysis of $CuSO_{4(aq)}$ between graphite electrodes?