Answer: Option (A) is the correct answer.
Explanation:
When there is an increase in oxidation state or release of electron from an atom then this process is known as oxidation.
In the reaction, [tex]Br_{2} + 2Cl^{-} \rightarrow Cl_{2} + 2Br[/tex], the oxidation and reduction equations are as follows.
Reduction: [tex]Br_{2} + 2e^{-} \rightarrow 2Br[/tex]
Oxidation: [tex]2Cl^{-} \rightarrow Cl_{2} + 2e^{-}[/tex]
Also, in the above reaction, oxidation state of chlorine increases from -1 to 0. Therefore, chlorine is oxidized in this reaction.
In the reaction, [tex]Cl_{2} + 2e^{-} \rightarrow 2Cl[/tex], the oxidation state of chlorine reduces from 0 to -1. Therefore, chlorine is reduced in this reaction.
In the reaction, [tex]2ClO_{3} + 12H^{+} \rightarrow Cl_{2} + 6H_{2}O[/tex], the oxidation state of chlorine reduces from +6 to 0. Therefore, chlorine is reduced in this reaction.
In the reaction, [tex]2Na + Cl_{2} \rightarrow 2NaCl[/tex], the oxidation state of chlorine reduces from 0 to -1. Therefore, chlorine is reduced in this reaction.
