Lesson 4.4.3.2

4.4.3.2 Different half-lives of radioactive isotopes Quiz: AQA Physics, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.4.3.2, Different half-lives of radioactive isotopes: 20 multiple choice questions for the AQA GCSE Physics (8463), Unit 4: Atomic structure, written with Revision Ninja.

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The 20 questions

  1. How do the half-lives of radioactive isotopes typically vary?

    • Exactly one year
    • Very wide range
    • Under one second
    • Always constant

  2. Why are isotopes with very short half-lives considered intensely hazardous?

    • Zero radiation emitted
    • Long duration hazard
    • High initial activity
    • Stable nuclei formed

  3. Why do isotopes with very long half-lives remain hazardous for ages?

    • Slow prolonged decay
    • Immediate stability
    • No radiation emitted
    • Instant total decay

  4. What determines how long the hazard from a radioactive isotope lasts?

    • Its half-life
    • Its chemical colour
    • Its total mass
    • Its physical state

  5. Between isotope A (half-life 2 s) and isotope B (half-life 20 years), which is hazardous longer?

    • Isotope B
    • Isotope A
    • Neither
    • Both equal

  6. Which isotope retains more activity after 80 days if isotope X has an 8-day half-life and Y has an 8-year half-life?

    • Y
    • Both equal
    • Zero
    • X

  7. Write 3.2 × 10⁶ years as an ordinary number.

    • 3.2 years
    • 320 000 years
    • 3 200 000 years
    • 32 000 000 years

  8. Write a half-life of 5 × 10⁻⁶ s as an ordinary decimal.

    • 500 000 s
    • 0.000005 s
    • 0.0005 s
    • 0.00005 s

  9. Which value is larger, 4 x 10^5 days or 9 x 10^3 days?

    • They are equal
    • 4 x 10^5 days
    • Cannot be determined
    • 9 x 10^3 days

  10. What is 0.00072 written in standard form?

    • 0.72 × 10⁻³
    • 7.2 × 10⁴
    • 7.2 × 10⁻⁴
    • 7.2 × 10⁻³

  11. Which radioactive sample would remain hazardous for the longest time?

    • Short half-life
    • Long half-life
    • Stable isotope
    • Zero half-life

  12. What do the very wide range of radioactive half-lives directly cause?

    • Identical activity
    • Different hazard durations
    • No radiation
    • Constant mass

  13. Why must radioactive waste with a long half-life be stored carefully?

    • Stays hazardous long
    • Loses all mass
    • Emits no radiation
    • Decays instantly

  14. How does the count rate from a radioactive sample with a very short half-life fall?

    • Constant
    • Slowly
    • Never
    • Rapidly

  15. Why is a short half-life preferred for radioactive isotopes used in medical diagnosis?

    • Increases permanence
    • Eliminates detection
    • Limits exposure time
    • Stops all decay

  16. Isotope P has a half-life of 1 × 10⁻³ s and isotope Q has a half-life of 5 × 10¹⁰ s. Which is hazardous for longer, and by roughly what factor?

    • Q, by about 5 × 10¹³ times
    • Q, by about 5 × 10³ times
    • P, by about 2 × 10⁻³ times
    • P, by about 5 × 10¹³ times

  17. What can differ between various isotopes of the exact same chemical element?

    • Proton number
    • Element name
    • Atomic number
    • Half-life

  18. After 10 hours, which source is more active if one has a 10-minute half-life and one has a 10-year half-life?

    • 10-year source
    • 10-minute source
    • Equal activity
    • Zero activity

  19. Apart from half-life, what else determines the hazard of a radioactive source?

    • Colour and density
    • Volume and shape
    • Radiation type and amount
    • Temperature and pressure

  20. A radioactive isotope has a half-life of 1 × 10³ years. Written as an ordinary number, this is:

    • 1000 years
    • 1 year
    • 10 000 years
    • 100 years

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