The correct option is A P→1,2;Q→1,2;R→2,3;S→1,5
(P) At Cathode: 2H+ + 2e− → H2(g)
At anode : (since it is a very dilute solution):
4OH− → O2 + 2H2O + 4e−
(Q)
At Cathode: 2H+ + 2e− → H2(g)
At anode : (since it is a very dilute solution):
4OH− → O2 + 2H2O + 4e−
(R)
At Cathode: 2H+ + 2e− → H2(g)
At anode : (since it is a concentrated solution):
2Cl− → Cl2 + 2e−
(S)
At Cathode: Ag+ + e− → Ag(s)
At anode :
4OH− → O2 + 2H2O + 4e−