Two identical samples of a tracer with a half-life of are prepared

PHYSICS · Single correct · A Level · Physics · Nuclear physics · Nuclear physics

Problem

Two identical samples of a tracer with a half-life of 10 min10\,\text{min} are prepared. Sample A is monitored until 12.5%12.5\% of its original nuclei remain, whereas Sample B is monitored until 6.25%6.25\% remain. Which statement correctly compares their decay times? (a) Sample B decays for twice as long as Sample A. (b) Sample B decays for one additional half-life beyond the time for Sample A. (c) The decay times are the same because both depend only on the half-life. (d) Sample B decays for 25%25\% longer than Sample A.

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