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Half-Life Question – Type 2
Half-Life Question – Type 2: What fraction remains of the original element?
What fraction of 1 gram of 14C remains unchanged after 17,190 years?
• Reffy, Table N (p. 6) shows that the half-life of 14C is 5714 years.
• One half-life = 5714 years
• 17,190 years = 3 half-lives ( 17,190 = 3) 5714
• Let’s figure out the fraction of 14C after 3 half-lives (when the original mass is 1 gram):
of 14C remains unchanged after 17,190 years.
1 half-life
2 half-lives
3 half-lives
1 2
21 /2 = 41
41 /2 = 81
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