the atomic mass of lithium is 6.941 amu. the reason that this value is not a whole number is that...?

Question

A) lithium does not exist in nature as a free element
B) the mass of lithium is the sum of the masses of the protons and electrons in the atom.
C) the mass of a proton is not exactly equal to 1 amu.
D) lithium has more than one isotope

Answer 1

D is the primary answer.

Tha atomic mass is the weighted average of all isotopes