Q.

A→r,s; B→r,p; C→p,q; D→sA. An aqueous  solution of AgNO3 with silver electrodes. In aqueous solution, ionisation of AgNO3 and H2O takes place.       AgNO3(s)⇌(aq)Ag+(aq)+NO3−(aq)H2O(l)⇌H+(aq)+OH−(aq)At cathode : Ag+ ions has less discharge potential than H+ ions so silver will be deposited at cathode.                        Ag+(aq)+e−⟶Ag(s)At anode : An equivalent amount of silver will be oxidised to Ag+ ions by releasing electrons.                       Ag(s)⟶Ag+(aq)+e−            Ag anode is attacked by NO3- ions, so it will also produce Ago in the solution.B. An aqueous solution of AgNO3 with platinum electrodes.    In aqueous solution, ionisation of AgNO3 and H2O both occur.                   AgNO3(s)⟶(aq)Ag+(aq)+NO3−(aq)H2O(l)⇌H+(aq)+OH−(aq)      As platinum electrodes are non-attackable electrodes, they will not be reacted upon by NO3- ions.At cathode Ag will be deposited at cathode.            Ag+(aq)+e−⟶Ag(s)At anode Out of NO3- and OH- ions, only OH- ions will be oxidised (due to less discharge potential) preferentially and NO3- ions will remain in the solution.             OH−(aq)⟶OH+e− 4OH⟶2H2O(l)+O2(g)So, oxygen gas is produced at anode. The solution remains acidic due to the Presence of HNO3.           H+(aq)+NO3−(aq)⇌HNO3(aq)C.A dilute solution of H2SO4 with platinum electrodes. Both H2SO4 and water ionise in the solution.        H2SO4(aq)⇌2H+(aq)+SO42−(aq)H2O(l)⇌2H+(aq)+OH−(aq)At cathode H+ ions will be reduced and hydrogen gas is produced at cathode.          H+(aq)+e−⟶H(g)H(g)+H(g)⟶H2(g)At anode OH- ions will be released preferentially and not SO4-ions due to less discharge potential.           OH−(aq)⟶OH+e−4OH⟶2H2O(l)+O2(g)         Oxygen gas is Produced at anode. Solution will be acidic and will contain H2SO4.D. An aqueous solution of CuCl2 with platinum electrodes. Both CuCl2 and water ionise as usual.             CuCl2⇌(aq)Cu2+(aq)+2Cl−(aq)H2O(l)⇌2H+(aq)+OH−(aq)     At cathode Cu2+ ions will be reduced preferentially due to less discharge potential than H+ ions.              Cu2+(aq)+2e−⟶Cu(s)      Copper metal is deposited at cathode.      At anode Cl- ions will be discharged in preference to OH- ions and chlorine gas is produced at anode.          Cl−(aq)⟶Cl(g)+e−Cl(g)+Cl(g)⟶Cl2(g)