JEE CHEMISTRY MCQ: d & f- BLOCK ELEMENTS

Which of the following conversions can be carried out by both acidified $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_4$ and acidified $\mathrm{KMnO}_4$ ?

(i) $\mathrm{Fe}^{2+} \rightarrow \mathrm{Fe}^{3+}+\mathrm{e}^{-}$

(ii) $\mathrm{I}^{-} \rightarrow \mathrm{IO}_3^{-}$

(iii) $\mathrm{I}^{-} \rightarrow \mathrm{I}_2$

(iv) $\mathrm{H}_2 \mathrm{~S} \rightarrow \mathrm{S}$