What kind of changes occur between atoms when substances undergo chemical reactions?

The atoms undergo chemical changes.

New substances may be a product of the reaction.

D-no effect on the rate

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 .