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3 marksRadioactivity

CAPE Physics Unit 2 · 2015 · Paper 2 · Question 3(b)(iii)

A sample of technetium-99m has an initial activity A_0 = 50\text{ GBq}. Activity is measured at two-hour intervals as shown in Table 4.

Use your graph to find the decay constant of technetium-99m.

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Other parts of this question

  1. 3(a)Complete Table 3 to indicate TWO properties and TWO reasons why a radioisotope such as technetium-99m can be used in this way.[4 marks]
  2. 3(b)(i)Complete Table 4 by calculating and inserting appropriate values in the relevant columns for A/A_0 and \ln(A/A_0).[2 marks]
  3. 3(b)(ii)On the grid provided in Figure 5, plot a graph of \ln(A/A_0) against time, t (in hours), and draw the best straight line through the points.[4 marks]
  4. 3(b)(iv)Use the decay constant to calculate the half-life, t_{1/2}, of technetium-99m.[2 marks]

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