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Edexcel IGCSE Physics 7.13 Half Life Calculations Questions

Apply half-life to activity, count rate, mass or nuclei, and use decay graphs to read a remaining quantity, estimate half-life or interpret carbon-14 dating.

Syllabus
First assessment 2019
Course
Physics 4PH1

Exam points

  • Calculate the remaining activity, count rate, mass or nuclei after determining how many half-lives have elapsed.
  • Calculate half-life from initial and later activity over a known time by identifying the number of halvings.
  • Plot decay data and draw a smooth curve of best fit for activity or carbon-14 percentage against time.
  • Read a decay graph to find a remaining quantity, estimate half-life or infer sample age from carbon-14 remaining.

Edexcel IGCSE Physics 7.13 Half Life Calculations Questions question 1

[Maximum number: 5]

This question is about radioactive isotopes used for medical imaging.

Question (a)

(a)

lodine-131 is represented by this symbol.

53131I{ }_{53}^{131} \mathrm{I}
[ 5 ]

Question (i)

(i)

The cross ( x ) on the graph shows the initial number of atoms in a sample of iodine-131.

Draw three more crosses ( × ) on the graph to show how the number of atoms of iodine-131 in the sample changes during three half-lives.
[iodine-131 half-life =8 days]

Figure for Question (i) — Edexcel IGCSE Physics
[ 3 ]

Question (ii)

(ii)

Use a curve of best fit on the graph to estimate the time taken for the number of atoms in the sample to decrease to 5000.
time taken = days

[ 2 ]
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