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2 marksRadioactivity

CAPE Physics Unit 2 · 2003 · Paper 2 · Question 9(b)(iii)

The radioactive nuclide ^99_43 Tc (Technetium) is produced by ^99_42 Mo decaying with a half-life of 67 hours; excited ^99_43 Tc de-excites emitting a gamma photon with a half-life of 6 hours.

A small tumor that has collected ^99 Tc emits 38 gamma ray photons per second at a given time. How many ^99 Tc nuclei are located in the tumor at this time?

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Other parts of this question

  1. 9(a)(i)Explain what is meant by the terms, 'activity', 'decay constant' and 'half life' of a radioactive substance.[3 marks]
  2. 9(a)(ii)State an equation relating the activity to the decay constant.[1 mark]
  3. 9(a)(iii)Draw a diagram to show the path of a stream of Beta particles and Gamma rays in a uniform electric field.[3 marks]
  4. 9(a)(iv)What instrument could be used to detect Beta and Gamma radiation?[1 mark]
  5. 9(b)(i)Write a nuclear equation to represent the ^99_42 Mo decaying to ^99_43 Tc.[2 marks]
  6. 9(b)(ii)A patient is injected with an 8.2 x 10^7 Bq sample of 99 Tc. How many gamma ray photons are initially produced within the patient each second?[2 marks]
  7. 9(c)(i)a)Calculate the fraction of the original ^40 K atoms remaining in the rock.[2 marks]
  8. 9(c)(i)b)Calculate the number of half lives that has elapsed.[2 marks]
  9. 9(c)(i)c)Calculate the age of the rock.[1 mark]
  10. 9(c)(ii)From your answers in (c)(i) deduce the age of the solar system.[1 mark]

More practice: the rest of this paper · more Radioactivity questions · all CAPE Physics Unit 2 past papers