The number of protons of an atom has is called its atomic number, which decides what kind of atom it is. Changes in the number of neutrons in an atom make an isotope and changes in the number of electrons makes positive or negative ion

29.1-12=17.1the answer is this one

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 .