4. Why do chemists use relative masses of atoms compared to a reference isotope rather than the actual masses of the atoms?
a. The actual mass of an electron is very large compared to the actual mass of a proton.
b. The actual masses of atoms are very small and difficult to work with.
c. The number of subatomic particles in atoms of different elements varies.
d. The actual masses of protons, electrons, and neutrons are not known.