Answer: The balanced half reaction is written below.
Step-by-step 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.
![X^(n+)+ne^-\rightarrow X](https://img.qammunity.org/2021/formulas/chemistry/college/d80ew5ldzgwhazfjazmbhnezbaiz2c7pjb.png)
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:
![O_2+2e^-\rightarrow 2O^(2-)](https://img.qammunity.org/2021/formulas/chemistry/college/pbcydylwbkq4g34muulfcxf0dcc8fcp12c.png)
Hence, the balanced half reaction is written above.