Silver has two naturally occurring isotopes with the following isotopic masses:

The average atomic mass of silver is 107.8682 amu. The fractional abundance of the lighter of the two isotopes is .

Question

Silver has two naturally occurring isotopes with the following isotopic masses:

The average atomic mass of silver is 107.8682 amu. The fractional abundance of the lighter of the two isotopes is .

Quizplus · Accepted Answer

Let x be the fractional abundance of the lighter isotope (with mass 106.9051 amu) and (1-x) be the fractional abundance of the heavier isotope (with mass 108.9048 amu).

The average atomic mass is then:
(106.9051 amu)(x) + (108.9048 amu)(1-x) = 107.8682 amu

Solving for x, we get x ≈ 0.5184, which means the fractional abundance of the lighter isotope is 0.5184 or 51.84%. Therefore, the answer is C.

Silver Has Two Naturally Occurring Isotopes with the Following Isotopic