Question

two liquids are mixed. the mixture heats up, and a gas is produced which is noted as the production of bubbles. is there evidence of a chemical or a physical change? why? (1)

Explanation:

A chemical change is characterized by the formation of new substances, energy - change (heating up in this case), and gas production. Physical changes do not result in new substances. Here, new substances (the gas) are formed and there is an energy change.

Answer:

There is evidence of a chemical change because new substances (the gas) are formed and there is an energy change (heating up).