Which of the following species can act as both an oxidizing agent and a reducing agent?

Solution

1. In ${\text{H}}_2{\text{O}}_2$, the oxidation state of oxygen is $-1$.
2. Oxygen can be oxidized to $0$ in ${\text{O}}_2$ or reduced to $-2$ in ${\text{H}}_2\text{O}$.
3. ${\text{KMnO}}_4$ has Mn in $+7$, which can only be reduced.
4. ${\text{SO}}_3$ has Sin $+6$, which can only be reduced.
5. ${\text{F}}_2$ has F in $0$, which can only be reduced.
6. Hence the answer is (A).