The activity of a radioactive sample is measured as 4800 Bq. After two half-lives, what is the activity?

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Question

The activity of a radioactive sample is measured as 4800 Bq. After two half-lives, what is the activity?

Accepted Answer

1200 Bq — After one half-life, activity halves to 4800 ÷ 2 = 2400 Bq. After a second half-life, it halves again to 2400 ÷ 2 = 1200 Bq. Option A is the activity after only one half-life. Option B would be after three half-lives (4800 → 2400 → 1200 → 600). Option D has no physical justification and likely arises from subtracting an incorrect fraction.

Answer

600 Bq

Answer

2400 Bq

Answer

1200 Bq

Answer

3200 Bq

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