Question -
Answer -
(i) An aqueous solution of AgNO_3 with silver electrodes.
(ii) An aqueous solution of AgNO_3with platinum electrodes.
(iii) A dilute solution of H_2SO_4with platinum electrodes.
(iv) An aqueous solution of CuCl_2 with platinum electrodes.
Answer
For dilute sulphuric acid,reaction (i) is preferred to produce O2 gas. But forconcentrated sulphuric acid, reaction (ii) occurs.
(iv) Atcathode:
The following reduction reactionscompete to take place at the cathode.
At the anode, the reaction with alower value of 
is preferred. But due tothe over-potential of oxygen, Cl− gets oxidized at the anode toproduce Cl2 gas.