In chemical changes, just as in physical changes, matter is conserved. The difference, in this case, is that the substances before and after the change have different physical and chemical properties.
D:Matter is not being conserved because there are 11 units in the reactants, one C8H8 and 10 O2, and 12 units in the products, eight CO2 and four H2O, so there is also more mass in the products that in the reactants.
