Multiple Choice
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
A) 8.1 × 10-10 yr
B) 2.4 × 109 yr
C) 2.8 × 109 yr
D) 4.6 × 109 yr
E) 6.8 × 109 yr
Correct Answer:

Verified
Correct Answer:
Verified
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