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Question

Match List I with List II.

List I (Conversion) List II(Number of Faraday required)
A. 1 mol of $H_{2}O$ to $O_{2}$ I. 3F
B. 1 mol of ${MnO}_{4}^{-}$to ${Mn}^{2 +}$ II. 2 F
C. $\ 1.5\text{ }mol$ of Ca from molten ${CaCl}_{2}$ III. 1F
D. 1 mol of FeO to ${Fe}_{2}O_{3}$ IV. 5 F

Choose the correct answer from the options given below:

Options

A.A-II, B-III, C-I, D-IV
B.A-III, B-IV, C-II, D-I
C.A-II, B-IV, C-I, D-III
D.A-III, B-IV, C-I, D-II

Solution

Sol. [Key Concept: Faraday requirements from electron counts]

A: 2H₂O → O₂ + 4H⁺ + 4e⁻, so oxidation of 1 mol H₂O requires 2F (A–II).

B: Mn changes from +7 to +2, requiring 5 mol electrons per mol MnO₄⁻,

hence 5F (B–IV).

C: Ca²⁺ + 2e⁻ → Ca, so 1.5 mol Ca requires 3F (C–I).

D: Fe changes from +2 in FeO to +3 in Fe₂O₃, so each mole FeO corresponds to 1F (D–III). Hence, option (3).

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