<u>Answer:</u> The chemical equation for the given reaction is given below.
<u>Explanation:</u>
When solid calcium oxide reacts with sulfur trioxide gas to produce solid calcium sulfate, the chemical equation follows:
This is the reaction when a metal oxide reacts with non-metal oxide to produce a salt.
By Stoichiometry of the reaction:
1 mole of solid calcium oxide reacts with 1 mole of sulfur trioxide gas to produce 1 mole of solid calcium sulfate.