Question detail
If a radioactive sample has a half-life of 5 years and its initial count rate is 200 counts/min, what will be the count rate after 15 years?
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
- A. 25 counts/min
- B. 50 counts/min
- C. 100 counts/min
- D. 75 counts/min
Answer
25 counts/min
Explanation
25 counts/min is correct because the worked solution uses remaining = initial / 2^n and substitutes the values from the question. This keeps activity, count rate, atomic number, mass number and neutron count distinct for Atomic structure.
Common mistake
Counting Half-Lives Mistake
Students often miscalculate the number of half-lives that have passed by not correctly halving the initial count rate multiple times.
To fix this, students should clearly outline the initial count rate and systematically halve it for each half-life until they reach the final count rate, ensuring they count the number of halvings accurately.
Related flashcards
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Related practice questions
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