Answer: The given statement is false.
Step-by-step explanation:
A chemical reaction is a reaction which brings change in chemical composition of reactants resulting in formation of new compounds which have different chemical properties.
For example,

So, when gas is produced in a chemical reaction then it means new compounds are formed due to breakage of old bonds and formation of new bonds.
Thus, we can conclude that the given statement gas produced from a reaction is a phase change and not a chemical change, is false.