Keesha performed a chemical reaction and the products looked quite different from the reactants. She knew the amount of matter had not changed due to the law of conservation of mass. According to the law of conservation of mass, what happens in a chemical reaction?

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .