Question

How do you decide whether an observed property of matter is a physical or a chemical property?

Answer 1

Physical properties can be measured without changing the identity of the substance. Chemical properties involve its reactivity.

Answer 2

A physical change is reversible, a chemical change is not. For example, the freezing of water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change - you can't 'unburn' it