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5.2 Radioactivity

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Question 91

A radioactive source is tested over a period of 20 hours with a radiation detector. The measurements are recorded in the table below:

Time / hours02468101214161820
Detector reading / (counts/s)17595553525201416151317
a.

Use the readings to:

  1. Suggest a value for the background count rate during the test.
  2. Determine the half-life of the sample.
[5]
b.

Carbon-14 has six protons and eight neutrons, giving it a nucleon number of 14. It decays by emitting a β\betaβ-particle. Complete the following nuclide equation to show this decay, where X\text{X}X represents the newly formed nuclide:

……C→……β+……X {}^{\dots}_{\dots}\text{C} \rightarrow {}^{\dots}_{\dots}\beta + {}^{\dots}_{\dots}\text{X} ……​C→……​β+……​X
[3]
c.

Three α\alphaα-particles are directed towards a thin gold foil containing gold nuclei:

  1. Particle 1 is on a direct head-on path toward the center of a gold nucleus.
  2. Particle 2 is traveling on a path that passes close to the side of a gold nucleus.
  3. Particle 3 is traveling on a path that is far from any gold nuclei.

Describe the path of each of these three α\alphaα-particles during and after their interaction with the gold foil.

[3]
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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