Boron has primarily two isotopes, one with an atomic mass of 11.0 amu and another with an atomic mass of 10.0 amu. If the abundance of the boron atom with a mass of 11.0 amu is 18.9 percent and the abundance of the other isotope is 81.1 percent, what would be the average mass of the boron atom?
A)10.2 amu
B)11.0 amu
C)10.0 amu
D)10.8 amu
E)not enough information given

Question

Quizplus · Accepted Answer

The average atomic mass is calculated by multiplying the mass of each isotope by its relative abundance and summing the results: (11.0 amu * 0.189) + (10.0 amu * 0.811) = 10.2 amu.

Boron Has Primarily Two Isotopes, One with an Atomic Mass