AP Chemistrymediummcq1 pt
Chlorine has two isotopes: Cl-35 (75.8% abundance) and Cl-37 (24.2%). What is the average atomic mass of chlorine?
A.35.5 amu
B.36.0 amu
C.35.0 amu
D.37.0 amu
Explanation
Core Concept
Weighted average: 0.758(35.0) + 0.242(37.0) = 26.53 + 8.95 = 35.48 ≈ 35.5 amu. Abundance weights each isotope mass; the result leans toward the more abundant Cl-35.
Correct Answer
A35.5 amu
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