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. $\Gamma^{-} \rightarrow \mathrm{I}_2$

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 :

The species which does not undergo disproportionation reaction is :

Thiosulphate reacts differently with iodine and bromine in the reactions given below:

$$\begin{aligned} & 2 \mathrm{~S}_2 \mathrm{O}_3^{2-}+\mathrm{I}_2 \rightarrow \mathrm{S}_4 \mathrm{O}_6^{2-}+2 \mathrm{I}^{-} \\ & \mathrm{S}_2 \mathrm{O}_3^{2-}+5 \mathrm{Br}_2+5 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{SO}_4^{2-}+4 \mathrm{Br}^{-}+10 \mathrm{H}^{+} \end{aligned}$$

Which of the following statement justifies the above dual behaviour of thiosulphate?

The number of ions from the following that are expected to behave as oxidising agent is :

$$\mathrm{Sn}^{4+}, \mathrm{Sn}^{2+}, \mathrm{Pb}^{2+}, \mathrm{Tl}^{3+}, \mathrm{Pb}^{4+}, \mathrm{Tl}^{+}$$