The aqueous solutions of the following salts were electrolyzed for 30 min with a current of 20 amp. Arrange the following in the increasing order of the amount of metal deposited at the cathode.

$ \text{(A) }\mathrm{WCl}_6 $
$ \text{(B) }\mathrm{ZnSO}_4 $
$ \text{(C) }\mathrm{HfCl}_4 $
$ \text{(D) }\mathrm{AgNO}_3 $

(Atomic mass of: W =184 μ, Zn = 65 μ, Hf = 178 μ and Ag = 108 μ)
Choose the correct answer from the options given below:

(A), (B), (C), (D)

The correct answer is Option (1) → (A), (B), (C), (D)
The amount of metal deposited at the cathode is proportional to the equivalent weight of the metal when the same current and time are used.

Reasoning:
By Faraday’s second law, for equal charge passed:

Amount deposited ∝ Equivalent weight = Atomic mass / Valency

Calculate for each salt:

(A) WCl₆ → W⁶⁺
Equivalent weight = 184 / 6 = 30.67

(B) ZnSO₄ → Zn²⁺
Equivalent weight = 65 / 2 = 32.5

(C) HfCl₄ → Hf⁴⁺
Equivalent weight = 178 / 4 = 44.5

(D) AgNO₃ → Ag⁺
Equivalent weight = 108 / 1 = 108

Increasing order of deposition (lowest to highest):

WCl₆ < ZnSO₄ < HfCl₄ < AgNO₃

Therefore, the order is:

(A), (B), (C), (D)