Answer: The balanced half reaction is written below.
Explanation:
Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.
[tex]X^{n+}+ne^-\rightarrow X[/tex]
When oxygen gas is reduced to oxide ions, the number of electron transferred are 2
The chemical equation for the reduction of oxygen gas to oxide ions follows:
[tex]O_2+2e^-\rightarrow 2O^{2-}[/tex]
Hence, the balanced half reaction is written above.