JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Redox Reactions and Electrochemistry

The correct group of halide ions which can be oxidised by oxygen in acidic medium is

(A) $Br^{-}$ only
(B) $Cl^{-}$ , $Br^{-}$ and $I^{-}$ only
(C) $Br^{-}$ and $I^{-}$ only
(D) $I^{-}$ only✓ Correct

Answer: (D)

Solution

Among the halide ions, only

I^{-}

can be oxidized by oxygen in acidic medium. This is because iodide is the strongest reducing agent among the halides (lowest reduction potential). The reaction is:

4 I^{-} (aq) + 4 H^{+} (aq) + O_{2} (g) \to 2 I_{2} (s) + 2 H_{2} O (l)

. Chloride and bromide are not oxidized under these conditions.

JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Single correct option

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