A certain element consists of two stable isotopes.The first has a mass of 14.0031 amu and a percent natural abundance of 99.63%.The second has a mass of 15.001 amu and a percent natural abundance of 0.37%.What is the atomic weight of the element?
A) 13.95 amu
B) 14.00 amu
C) 14.01 amu
D) 14.50 amu
E) 19.50 amu

Question

Quizplus · Accepted Answer

Atomic weight = (mass of isotope 1 x percent abundance of isotope 1) + (mass of isotope 2 x percent abundance of isotope 2)
Atomic weight = (14.0031 amu x 99.63%) + (15.001 amu x 0.37%)
Atomic weight = 13.95346 amu + 0.055537 amu
Atomic weight = 14.008 amu, which rounds to 14.01 amu.

A Certain Element Consists of Two Stable Isotopes