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4 marksRadioactivity

CAPE Physics Unit 2 · 2007 · Paper 2 · Question 8(b)(iv)

A radioactive source has an activity of 2.5 × 10⁶ Bq at t = 0 and a half-life of 4.5 years (where 1 year = 3.15 × 10⁷ s).

If the source cannot be safely disposed of until its activity falls below 100 Bq, calculate the minimum number of years it must be stored.

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Other parts of this question

  1. 8(a)(i)Describe, with a labelled diagram of the apparatus, an experiment to show that radioactive decay is a random process, using a small long-lived radium source.…[4 marks]
  2. 8(a)(ii)State the mathematical relationship between the number of parent nuclei present and the activity of a radioactive source.[2 marks]
  3. 8(a)(iii)Explain the meaning of 'half-life' and state the equation relating half-life to the decay constant λ.[2 marks]
  4. 8(b)(i)Calculate the number of parent atoms present at time t = 0.[3 marks]
  5. 8(b)(ii)Determine the activity of the source after 9 years.[2 marks]
  6. 8(b)(iii)Calculate the activity of the source after 12 years.[3 marks]

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