Concept:The Law of Conservation of Mass states that mass is neither created nor destroyed during any ordinary physical or chemical change.
Explanation:In a physical change, only the form or state of a substance changes while its chemical identity stays the same.
For example, ice melts into water:
H2O(s)→H2O(l).
In a chemical change, new substances are formed from the original substances.
For example, iron combines with oxygen to form rust:
4Fe(s)+3O2(g)→2Fe2O3(s).
In every change, the total mass before the change equals the total mass after the change.
Thus, both physical and chemical changes produce no change in mass.
Chemical changes are not easily reversible in most cases, so option A is incorrect.
A change of state is not necessary in every physical or chemical change, so option B is incorrect.
Great heat change is not a feature of every physical or chemical change, so option D is incorrect.
Answer:C. produce no change in mass.