State the reason for difference in product formed at the anode during electrolysis of aq. CuSO₄ using :

(i) active electrode — copper anode

(ii) inert electrode — platinum anode.

Give the electrode reactions for formation of

(i) Lead metal and bromine vapours from molten PbBr₂ using inert electrodes

(ii) H₂ and O₂ gas [2:1] from acidified water using inert Pt electrodes.

From the ions –

(i) SO₄^2– and OH^1–

(ii) Cu²⁺ and H¹⁺

(iii) Ag¹⁺ and H¹⁺

state giving reasons which ion is discharged at the respective electrode in each case.

Explain the terms :

(i) metal activity or electro chemical series

(ii) selective discharge of ions.