Which of the following oxidation reactions are carried out by both \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) and \(\mathrm{KMnO}_{4}\) in acidic medium? A. \(\mathrm{I}^{-} \rightarrow \mathrm{I}_{2}\) B. \(\mathrm{S}^{2-} \rightarrow \mathrm{S}\) C. \(\mathrm{Fe}^{2+} \rightarrow \mathrm{Fe}^{3+}\) D. \(\mathrm{I}^{-} \rightarrow \mathrm{IO}_{3}^{-}\) E. \(\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \rightarrow \mathrm{SO}_{4}^{2-}\) Choose the correct answer from the options given below:

JEE Main · 2025 · 28 Jan 2025 · Shift 1 · d and f Block Elements

Which of the following oxidation reactions are carried out by both

K_{2} Cr_{2} O_{7}

and

KMnO_{4}

in acidic medium?
A.

I^{-} \to I_{2}

S^{2 -} \to S

Fe^{2 +} \to Fe^{3 +}

I^{-} \to IO_{3}^{-}

S_{2} O_{3}^{2 -} \to SO_{4}^{2 -}

Choose the correct answer from the options given below:

Answer: (C)

In acidic medium, both

K_{2} C r_{2} O_{7}

and

K M n O_{4}

are strong enough oxidants to carry out

I^{-} \to I_{2}

S^{2 -} \to S

and

F e^{2 +} \to F e^{3 +}

— these are the standard titration/qualitative reactions common to both. Pushing iodide all the way to iodate (

I O_{3}^{-}

) or thiosulfate all the way to sulfate needs a more forcing oxidant than dichromate provides; dichromate stops short of these, so only

K M n O_{4}

accomplishes D and E. The oxidations common to both reagents are A, B and C.

JEE Main · 2025 · 28 Jan 2025 · Shift 1 · Single correct option