13 (a) State what is meant by radioactive decay. (b) The variation with time t of the number N of technetium-101 nuclei in a sample of radioactive material is shown in Fig. 13.1. [Figure 13.1] (i) Use Fig. 13.1 to determine the activity, in Bq, of the sample of technetium-101 at time t = 14.0 minutes. Show your working. activity = .............................................. Bq (ii) Without calculating the half-life of technetium-101, use your answer in (i) to determine the decay constant λ of technetium-101. λ = .............................................. s⁻¹

1. (a)State what is meant by radioactive decay.[2]
2. (b)(i)Use Fig. 13.1 to determine the activity, in Bq, of the sample of technetium-101 at time t = 14.0 minutes. Show your working. activity = .............................................. Bq[4]
3. (b)(ii)Without calculating the half-life of technetium-101, use your answer in (i) to determine the decay constant λ of technetium-101. λ = .............................................. s⁻¹[2]

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