Three electrolytic cells A, B, and C containing solutions of ZnSO ₄ , AgNO ₃ , and CuSO ₄ , respectively, are connected in series. A steady current is passed through them until a certain amount of metal is deposited at the respective cathodes. The ratio of the number of moles of Zn, Ag, and Cu deposited is :

Step-by-step solution

When cells are connected in series, the same quantity of electricity ( Q ) passes through each cell. According to Faraday's laws of electrolysis, the number of moles of a substance deposited is given by: Moles = Q n F Since Q and F are constant for all three cells, the number of moles deposited is inversely proportional to the valency ( n -factor) of the metal ion. The reduction reactions at the cathodes are: Zn ²⁺ + 2 e ⁻ Zn (n = 2) Ag ⁺ + e ⁻ Ag (n = 1) Cu ²⁺ + 2 e ⁻ Cu (n = 2) The ratio of the number of moles of