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thenamehobbs thenamehobbs
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The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 × 109 yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms. The age of the rock is



8.1 × 10–10 yr.



2.4 × 109 yr.



2.8 × 109 yr.



4.6 × 109 yr.



6.8 × 109 yr.

Textbook 
Chemistry: Atoms First

Chemistry: Atoms First


Edition: 4th
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thevoicexxxthevoicexxx
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