Answer : The correct option is, [tex]2F^-\rightarrow F_2+2e^-[/tex]
Explanation :
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In the oxidation reaction, the oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Oxidizing agent : It is defined as the substance which has ability to oxidize the other substances by gaining electrons.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In the reduction reaction, the oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
Reducing agent : It is defined as the substance which has ability to reduce the other substances by losing electrons.
From the given options, we conclude that
(1) [tex]O_2+4e^-\rightarrow 2O^{2-}[/tex]
(2) [tex]SO_3+H_2O\rightarrow SO_4^{2-}+2H^+[/tex]
(3) [tex]MnO_2+4H^++2e^-\rightarrow Mn^{2+}+2H_2O[/tex]
The reaction 1, 2 and 3 shows the reduction reaction. So, it requires a reducing agent.
(4) [tex]2F^-\rightarrow F_2+2e^-[/tex]
The reaction 4 shows the oxidation reaction. Therefore, it requires an oxidizing agent.
Therefore, the correct option is, [tex]2F^-\rightarrow F_2+2e^-[/tex]
