Half-life of ¹⁴C is 5730 years. Sample with 25% original activity is:
A11460 years old (= 2 half-lives, since (1/2)² = 1/4)
B2865 years old
C5730 years old
DInfinite
Answer & Solution
Correct answer: A. 11460 years old (= 2 half-lives, since (1/2)² = 1/4)
25% remaining = (1/2)² → 2 half-lives = 2 × 5730 = 11460 years. Carbon-14 dating is reliable for samples up to ~50,000 years old.
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