A student combines two liquids in a beaker. She observes that the mass of the combined liquid is less than the mass of the two separate liquids. The student claims that this observation shows that matter is not conserved in chemical reactions. Which statement explains why the students claim is incorrect.
A the reaction did not change the physical properties of the liquids
B the reaction produce a gas that escaped the beaker
C the combine liquid was warmer than the two separate liquids
D the product contains fewer items than the reactants