Question

Which of the following can act as both oxidizing and reducing agent?
(A) $C{H_2}{O_2}$
(B) $HN{O_2}$
(C) $KN{O_3}$
(D) ${O_2}$

Answer 1

Hint : To solve this question we have to understand the oxidation states of a particular atom in a molecule. Atom that has the ability to undergo both the reduction and oxidation is considered to be both the oxidizing and reducing agent.

Complete Step By Step Answer:
When the atom loses its electron, it undergoes the oxidation and hence, it is known as the reducing agent, whereas, when the atom gains electrons, it means it has undergone reduction and is known as oxidising agent.
So, by looking all the options given, and calculating their oxidation states,
Example for $KN{O_3}$
The oxidation state of $N$ in $KN{O_3}$ is $+ 5$ and since this is the highest oxidation state, nitrogen can attain, so it can only act as a reducing agent as it cannot undergo further oxidation.
And when we come to option B i.e. $HN{O_2}$
The oxidation state of $N$ in $HN{O_2}$ is $+ 3$
As, $+ 3$ is not the higher oxidation state of nitrogen. So, this means that it can undergo both the oxidation and the reduction.
Thus option B is correct i.e. $HN{O_2}$ Can act both as oxidizing as well as reducing agent.

Note :
For a chemical species to act both as oxidizing as well as reducing agent, it should be in the intermediately form .Also, oxygen in ${H_2}{O_2}$ can undergo both the oxidation and the reduction. Thus is a redox reaction.