alleryStart learning →What is the half-life of a radioactive sample?
AThe total time until every nucleus in the sample has decayed
BThe time it takes to double the number of nuclei present
CThe average lifetime of just one single proton
DThe time in which half of the original number of nuclei decay
Answer & Solution
Correct answer: D. The time in which half of the original number of nuclei decay
1. A radioactive sample loses nuclei to decay at a predictable statistical rate.
2. Half-life is defined as the time in which half of the original number of nuclei decay.
3. It is not the total time for every nucleus to decay, since decay continues indefinitely in ever-smaller amounts.
4. It does not describe a doubling process, and it is not simply the lifetime of one proton.
5. So the time for half the original nuclei to decay is correct.
_Source: OpenStax Physics (CC BY 4.0), Ch 22 "The Atom", section 22.3 Half Life and Radiometric Dating_
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