An element consists of three isotopes.The abundance of one isotope is 92.21% and its atomic mass is 27.97693 u.The abundance of the second isotope is 4.70% and its atomic mass is 28.97649 u.The atomic mass of the third isotope is 29.97376 u.What is the atomic weight of the element?
A) 28.09 u
B) 28.98 u
C) 28.96 u
D) 29.87 u
E) 29.07 u

Question

Quizplus · Accepted Answer

The atomic weight is calculated by multiplying the atomic mass of each isotope by its abundance (expressed as a fraction), and then summing these values: (0.9221 * 27.97693) + (0.0470 * 28.97649) + (0.0309 * 29.97376) = 28.09 u.

An Element Consists of Three Isotopes