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5.2.4a Half-life

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Question 66

A radioactive isotope has a half-life of 5 years5\text{ years}5 years.

A sample gives a count rate of 240 counts/s240\text{ counts/s}240 counts/s on a detector.

Which calculation is used to predict the count rate after 15 years15\text{ years}15 years?

A

240×12×12×12240 \times \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2}240×21​×21​×21​

B

240×12×12×12×12240 \times \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2}240×21​×21​×21​×21​

C

240×515240 \times \frac{5}{15}240×155​

D

240×155×12240 \times \frac{15}{5} \times \frac{1}{2}240×515​×21​

Markscheme

5.2.4a Half-life Questions

  1. IGCSE
  2. /Physics
  3. /5.2.4a Half-life

144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.

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