Mostly elements have fractional atomic masses because of______________________?
Correct answer: C. Atmoic masses are average masses of isotopes proportional to their relative abundance
- A. Mass of an atom itself is in fraction
- B. Atomic masses are average masses of isobars
- C. Atmoic masses are average masses of isotopes proportional to their relative abundance
- D. Atmoic masses are average masses of isotopes
Explanation
The atomic mass of an element is a weighted average of the masses of its naturally occurring isotopes, with each isotope weighted according to its relative abundance. Thus the more abundant isotopes contribute more to the reported atomic mass. Students may choose d, but it is incomplete because it ignores the essential weighting by relative abundance.
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