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3 marksRadioactivity

CAPE Physics Unit 2 · 2010 · Paper 2 · Question 3(b)(ii)

Radon-220 has a half-life of 54 s, decaying by α-emission (one particle per decaying atom).

A laboratory is deemed safe after a Radon-220 leak when the activity decreases to less than 0.1% of its original value. Calculate the MINIMUM number of minutes for which the laboratory must remain closed.

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Other parts of this question

  1. 3(a)Describe how to accurately measure the half-life of Radon-220, an α-emitter with a short half-life easily separated from its powdered solid parent, detailing…[7 marks]
  2. 3(b)(i)Calculate how many α-particles would be emitted by a 4 mg sample of ²²⁰₈₆Rn in 108 seconds.[5 marks]

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