Question

1. which best explains why the periodic table lists one atomic mass for mg?

a it changes depending on the sample size
b it is a weighted average of all isotopes
c it shows the most common isotope only
d it shows the heaviest isotope

Explanation:

The atomic mass listed for an element on the periodic table is the weighted - average of the masses of all its naturally - occurring isotopes, taking into account their relative abundances.

Answer:

B. It is a weighted average of all isotopes