Question

Which of the following oxidation reactions are carried out by both \(K_2Cr_2O_7\) and \(KMnO_4\) in acidic medium ?

A. \(\mathrm{I}^{-} \rightarrow \mathrm{I}_{2}\)

B. \(S^{2-} \rightarrow S\)

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 :

(1) B, C and D only

(2) A, D and E only

(3) A, B and C only

(4) C, D and E only

Answer 1

Correct option is : (3) A, B and C only 

\(\mathrm{I}^{-} \xrightarrow{\mathrm{H}^{+}} \mathrm{I}_{2}\quad \mathrm{I}^{-} \xrightarrow{\mathrm{OH}^{-}} \mathrm{IO}_{3}^{-} \) 

\( \mathrm{S}^{-2} \xrightarrow{\mathrm{H}^{+}} \mathrm{S} \quad \mathrm{S}_{2} \mathrm{O}_{3}^{2-} \xrightarrow{\mathrm{OH}^{-}} \mathrm{SO}_{4}^{2-}\) 

\(\mathrm{Fe}^{+2} \longrightarrow \mathrm{Fe}^{+3}\) 

\(\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \xrightarrow{\mathrm{H}^{+}} \mathrm{S} \downarrow+\mathrm{SO}_{4}^{2-}\)