Question

What is the major difference between chemical and physical changes?

A. Chemical changes always involve the release of some gas, which is not the case with physical changes.
B. Physical changes always involve the release of some gas, which is not the case with chemical changes.
C. New substances are always produced in chemical changes, which is not the case with physical changes.
D. New substance are always produced in physical changes, which is not the case with chemical changes.

Answer 1

C. New substances are always produced in chemical changes, which is not the case with physical changes. For example, when you cut wood into smaller pieces you still have wood in the end. But, with a chemical change you change the substance's whole composition. For example when you add two hydrogen's to one oxygen you have water and it can't break down from that.