Answer
14.007 amu
Work Step by Step
To calculate the average atomic mass we add the products of the relative abundance and the mass of each isotope together.
Isotope 1: mass= 14.003 amu (99.63%)
Isotope 2: mass= 15.000 amu (0.37%)
= 14.003 amu (99.63%) + 15.000 amu (0.37%)
= 14.003 amu (0.9963) + 15.000 amu (0.0037)
= 14.007 amu
