Question detail

If the initial count rate of a radioactive sample is 80 counts per minute, what will the count rate be after two half-lives?

Try the question, check the answer, then read the explanation to understand the curriculum point.

At a glance

MCQ

Type

practice

Style

Topic

Atoms and nuclear radiation

Question

20 counts per minute

After one half-life, the count rate would be 40 counts per minute, and after the second half-life, it would halve again to 20 counts per minute.

Misinterpreting Decay Curves

Students often confuse the shape of the decay curve, thinking it is linear rather than exponential.

Review the characteristics of exponential decay, noting that the count rate decreases rapidly at first and then more slowly over time.

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