You will learn that matter is neither created nor destroyed in any chemical change. is this statement a theory or a law? explain your answer.

This is a law. That is because it cannot be refuted in any way. A theory often depends on perfect conditions. Even simple theories often are based on perfect conditions that cannot be found on earth. Unlike it, laws are applicable no matter where and how you are. Such are for example Newton's laws or laws of thermodynamics.

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 .