One isotope of oxygen differs from another isotope of oxygen in *

Each isotope of Oxygen has a different number of neutrons

Further explanation

The elements in nature have several types of isotopes

Atomic mass is the average atomic mass of all its isotopes

Isotopes are atoms has the same number of protons but has a different number of neutrons.

So Isotopes are elements that have the same Atomic Number (Proton)

Some of the isotopes of oxygen are:

Each isotope has 8 protons and 8 electrons but has a different number of neutrons

For O-16: number of neutrons = 16-8 = 8

For O-17: number of neutrons = 17-8 = 9

For O-18: number of neutrons = 18-8 = 10

Enzyme make a hormone as a catalyst

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 .