A radioactive isotope has a half-life of 8 days. After 24 days, what fraction of the original number of atoms remains?

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Question

A radioactive isotope has a half-life of 8 days. After 24 days, what fraction of the original number of atoms remains?

Accepted Answer

1/8 — 24 days ÷ 8 days per half-life = 3 half-lives. After each half-life the number of atoms halves: (1/2)³ = 1/8. Option A (1/4) corresponds to only 2 half-lives. Option B (1/6) is a common arithmetic error with no physical basis. Option D (1/3) incorrectly divides 1 by the number of half-lives rather than raising 1/2 to that power.

Answer

1/6

Answer

1/4

Answer

1/8

Answer

1/3

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