An element found in another galaxy exists as two isotopes.If 80.0 percent of the atoms have an atomic mass of 80.00 atomic mass units and the other 20.0 percent have an atomic mass of 82.00 atomic mass units,what is the atomic mass of the element?
A)81.0 atomic mass units
B)64.0 atomic mass units
C)80.4 atomic mass units
D)16.4 atomic mass units
E)81.6 atomic mass units

Question

Quizplus · Accepted Answer

To find the atomic mass, we need to take a weighted average of the two isotopes, based on their abundance. Using the given percentages:

(0.8)(80.00 amu) + (0.2)(82.00 amu) = 80.40 amu

Therefore, the atomic mass of the element is 80.4 atomic mass units.

An Element Found in Another Galaxy Exists as Two Isotopes