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5.2 Radioactivity

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Question 185

The count rate due to a sample of a radioactive isotope is measured for 75 minutes.

Time / minutesCount rate / (counts/second)06401551030400453206025075200 \begin{array}{|c|c|} \hline \text{Time / minutes} & \text{Count rate / (counts/second)} \\ \hline 0 & 640 \\ 15 & 510 \\ 30 & 400 \\ 45 & 320 \\ 60 & 250 \\ 75 & 200 \\ \hline \end{array} Time / minutes01530456075​Count rate / (counts/second)640510400320250200​​

What is the half-life of the isotope?

A

15 minutes15\text{ minutes}15 minutes

B

30 minutes30\text{ minutes}30 minutes

C

45 minutes45\text{ minutes}45 minutes

D

75 minutes75\text{ minutes}75 minutes

Markscheme

5.2 Radioactivity Questions

  1. IGCSE
  2. /Physics
  3. /5.2 Radioactivity

484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.

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