Question

Which of the following groups of molecules act both as oxidising agent as well as reducing agent?

• A. $KMn{O}_4,O_3,S{O}_3$
• B. $HCl{O}_4,HN{O}_2,H_2{O}_2$
• C. $HN{O}_2,S{O}_2,H_2{O}_2$
• D. $HN{O}_3,S{O}_2,H_{2}S{O}_4$

Answer 1

The correct option is C $HN{O}_2,S{O}_2,H_2{O}_2$

When an atom present in its intermediate oxidation state then it can act both oxidizing agents as well as a reducing agent.

1.In $KMn{O}_4$,$Mn$ is in +7 oxidation state so it cannot acts as reducing agent. $O_3$ can only act as an oxidising agent due to its unstable nature.In $S{O}_3$, $S$ is in +6 oxidation state so it cannot acts as reducing agent.

2.In $HCl{O}_4$,$Cl$ is in +7 oxidation state so it cannot acts as reducing agent.$HN{O}_2$ can act both oxidizing as well as reducing agent because $N$ is in +3 oxidation state.In $H_2{O}_2$, $O$ is in -1 oxidation state so can act both oxidizing as well as reducing agent.

3.In $HN{O}_2$ can act both oxidizing as well as reducing agent because $N$ is in +3 oxidation state.In $H_2{O}_2$, $O$ is in -1 oxidation state so can act both oxidizing as well as reducing agent.In $S{O}_2$, $S$ is in +4 oxidation state so it can act as both oxidizing agent as well as reducing agent.

4.$HN{O}_2$ can act both oxidizing as well as reducing agent because $N$ is in +3 oxidation state.In $S{O}_2$, $S$ is in +4 oxidation state so it can act as both oxidizing agent as well as reducing agent.But $H_{2}S{O}_4$ cannot acts as reducing agent because $S$ is present in its higher oxidation state.

So (C) is a correct answer.