Chemistry Question, Please Help?

A pure white, solid material that looks like table salt releases gas when heated under certain conditions. There is no change in the appearance of the solid, but the reactivity of the material changes.

a. Did a chemical or physical change occur? How do you know? ( I know that it would be a chemical change, but how would I explain it clearly?)

b. Was the original material an element or a compound? Explain your answer.


a. This is a chemical change as new substances are produced ( i.e.the gas and the more reactive substance)

b. The original substance was a compound as it contained more than one type of atom and broke up into simpler substances - both of which an an element is incapable of doing.