Question

Which of the following acts as an oxidising as well as reducing agent?

• A. $N{a}_{2}O$
• B. $H_{2}S{O}_4$
• C. $HN{O}_3$
• D. $HN{O}_2$

Answer 1

Answer: (D)

As in $HN{O}_2$ , $\text{N}$ is in $\text{+3}$ oxidation state, but nitrogen can have oxidation states from $-\text{3}$ to $+5$ , so it is in between the maximum and minimum oxidation state hence it can either get reduced or oxidized, depending on the conditions. It means it can act both as an oxidizing and a reducing agent. It can work both as oxidising as well as reducing agent.
(I) As an oxidising agent:
$HN{O}_2+2H^{+}+e^{-}\to NO+H_{2}O$
(II) As reducing agent:
$HN{O}_2+H_{2}O\to N{O}_3^{-}+3H^{+}+2e^{-}$