Answer: Atomic mass of gallium = 69.72304093 amu
Step-by-step explanation:
We calculate the atomic mass of Gallium by using the Relative abundance of the isotopes.
Atomic mass =mass x Natural Abundance of Isotope 1 +mass x Natural Abundance of Isotope 2
(60.11/100 x 68.9256) + (39.89/100 x 70.9247)
= 41.43117816 + 28.29186283 = 69.72304093 amu