Question detail
A radioactive isotope has a half-life of 10 years. If the initial activity is 2000 Bq, what will be the activity after 30 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. 250 Bq
- B. 500 Bq
- C. 1000 Bq
- D. 1500 Bq
Answer
250 Bq
Explanation
250 Bq 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
Misunderstanding Half-Life Calculations
Students often confuse the concept of half-life with the total decay time, leading to incorrect calculations of remaining count rate or activity.
To accurately calculate the remaining count rate after a number of half-lives, remember that each half-life reduces the count rate by half. Use the formula: remaining count rate = initial count rate × (0.5)^n, where n is the number of half-lives.
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