How can you tell isotopes apart?

Isotopes have different amount of neutrons.
So you can tell what is an isotope by it neutrons. 

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 .

Idon't know hope someone you