Units (Radioactivity)

1 mark · Normal

A Geiger-Müller tube records 90 decays in 3 minutes. Which option correctly expresses this quantity as an activity in SI units?

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Correct option: 30 Bq

Common mistakes: 90 Bq (using count, not rate); 3 Bq (using time as value, not as seconds); 270 Bq (incorrectly multiplying)

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Marking points

A1 · 1 mark · Correct answer: 30 Bq

Worked solution

Activity .

However, since activity in Bq is typically stated as decays per second, 90 decays in 3 minutes = 30 Bq. Thus, the correct option is 30 Bq.