Question

how do we know this fireworks display is a chemical change?
there is an increase in heat.
bubbles were produced.
there is a formation of a solid.

Explanation:

In a chemical change, new substances are formed and energy is often released or absorbed. Fireworks involve the rapid combustion of chemicals, which releases heat, light, and sound. An increase in heat is a sign of an exothermic chemical reaction taking place during the fireworks display. Bubbles are more characteristic of reactions in solutions like acid - base reactions producing gases. Formation of a solid is a precipitate in solution reactions or some solid - state reactions not typical of fireworks.

Answer:

There is an increase in heat.