Physics 0625 · IGCSE · Radioactivity

Radioactivity — practice question

A detector is positioned close to a radioactive isotope and registers a count rate of $700\ \text{counts/min}$. The isotope has a half-life of $8\ \text{min}$. The mean background count rate is $60\ \text{counts/min}$. What count rate does the detector record after $16\ \text{min}$?

  • A$100\ \text{counts/min}$
  • B$160\ \text{counts/min}$
  • C$175\ \text{counts/min}$
  • D$220\ \text{counts/min}$

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