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An element, X has the following isotopic composition: 200X: 90%; 199X: 8.0%; 202X: 2.0%. The weighted average atomic mass of the naturally occurring element X is closest to:

1. 201 amu
2. 202 amu
3. 199 amu
4. 200 amu

Correct answer: 200 amu

Solution

The weighted average atomic mass of the naturally occurring element X can be calculated using the formula A = (Σn × m) / Σn, where n is the number of atoms of each isotope and m is the mass of each isotope. Given the isotopic composition of X, the weighted average atomic mass is approximately 200 amu.

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