Here's how to determine the net ionic equation for the reaction of carbon dioxide gas with hot solid sodium oxide:

1. Write the balanced chemical equation:

```

CO₂(g) + Na₂O(s) → Na₂CO₃(s)

```

2. Identify the states of matter:

* CO₂(g) - Carbon dioxide gas

* Na₂O(s) - Sodium oxide solid

* Na₂CO₃(s) - Sodium carbonate solid

3. Determine the soluble species:

* Only soluble species will dissociate into ions in solution. In this reaction, none of the reactants or products are soluble in water. Therefore, there are no ions present.

4. Write the net ionic equation:

Since there are no ions present in solution, there is no net ionic equation for this reaction.

Explanation:

The reaction between carbon dioxide and sodium oxide is a solid-state reaction. The reactants and products are all in the solid phase. Net ionic equations are only used to represent reactions that occur in aqueous solutions where ions are present.