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Physics (OCR Foundation)
Nuclear physics

Starter quiz

  • Which of the following describes what is meant by a radioactive isotope having a half–life of 15 minutes?
    • It takes 15 minutes for all of the nuclei to decay.
    • It takes 15 minutes for one nucleus to decay.
    • It takes 15 minutes for half of the nuclei to decay.  ✓
  • How do the half–lives of different radioactive isotopes compare?
    • All radioactive isotopes have the same half–life.
    • Isotopes of the same element have the same half–life.
    • Half–life values vary between different isotopes and elements.  ✓
    • Half–life does not depend on the radioactive isotope.
  • What effect does increasing the temperature have on the half–life of a radioactive isotope?
    • Increasing the temperature increases the half–life.
    • Increasing the temperature decreases the half–life.
    • Increasing the temperature has no effect on the half–life.  ✓
  • Starting with the longest, sort the following radioactive isotopes into order of decreasing half–life.
    • 1
      ⇔
      plutonium–239: half–life = 24,100 years
    • 2
      ⇔
      americium–241: half–life = 432 years
    • 3
      ⇔
      hydrogen–3 (tritium): half–life = 12.3 years
    • 4
      ⇔
      iodine–131: half–life = 8 days
    • 5
      ⇔
      fluorine–18: half–life = 110 minutes
    • 6
      ⇔
      polonium–214: half–life = 0.16 milliseconds
  • How does the half–life of a carbon–14 atom in a carbon monoxide (CO) molecule compare to its half–life in a carbon dioxide (CO₂) molecule?
    • It is longer when part of the CO molecule.
    • It is longer when part of the CO₂ molecule.
    • It is the same, regardless of the molecule it is part of.  ✓
  • A radioactive isotope has a half–life of 10 hours. Match each of the following fractions of the sample remaining to the correct amount of time that has passed.
    • 1
      ⇔
      0 hours ✓
    • ½
      ⇔
      10 hours ✓
    • ¼
      ⇔
      20 hours ✓
    • ⅛
      ⇔
      30 hours ✓
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