Question

What would be a good hypothesis for a lab in which the purpose is to identify the differences between chemical and physical changes.

Answer 1

I think either of the below would be satisfactory.
a) Chemical and physical properties for compounds are the same.
b) Chemical and physical properties for compounds are not the same.
These can be changed, easily, depending upon the kinds of tests you intend to do.

Answer 2

Would this sound reasonable?
If I test substances, then I will be able to identify the physcial and chemical changes.

Answer 3

Yes, but I would rewrite it in third person. For example, Physical and Chemical properties can be identified by testing substances. Or some variation of that.