Answer:
C. Chemical reactions create new atoms, which will increase the mass of the substance.
Step-by-step explanation:
It is not true that according to the Law of conservation of mass that mass of the substance will increase during chemical reactions.
During a chemical reaction, new atoms are not being created. The atoms of the reactant simply recombines to given a different product or compound. The atoms are still the same only the compound or product form differs.
According to the law of conservation of mass "in a chemical change, matter is neither created nor destroyed but bonds are broken and atoms combine".
By virtue of this, chemical reactions conserves mass so that the mass we start with is the same we end with since no new matter is destroyed nor created.