Skip to main content
Chemistry LibreTexts

General J001: Radioactivity

  • Page ID
  • The following questions relate to various aspects of radioactivity and radiochemistry, it may be useful to review the concepts and definitions associated with radiochemistry before attempting these questions. These questions are for self-testing only, and are not suitable for assignments or exams.

    Express each value:

    1.A 1 g sample of 207Po is allowed to decay. It has a half life of 6 hours. How much 207Po will remain after 12 hours?

    A 125 mg
    B 250 mg
    C 333 mg
    D 500 mg
    E 667 mg

    2.What nucleus is formed as a result of the α-decay of 21084Po?

    A 21085At
    B 21484Po
    C 21486Rn
    D 20682Pb
    E 21280Hg

    3.What nucleus is formed as a result of the β-minus decay of 5524Cr?

    A 5425Mn
    B 5525Mn
    C 5524Cr
    D 5523V
    E 5423V

    4.Why is radioactive iodine (131I) useful in medicine?

    A The alpha radiation it emits helps to neutralize the beta radiation in our bodies.
    B Since it behaves chemically like non radioactive iodine, it is absorbed into the thyroid gland, which can then be monitored for its activity (using radiation).
    C It behaves chemically like sodium, and thus it allows doctors to monitor sodium levels in the heart, by measuring radiation levels.
    D Because it has 78 neutrons in its nucleus.
    E It emits positive ions, which help patients to feel better.

    5.A 1 g sample of 207Po is allowed to decay. After 5.7 hours, only 500 mg of the original 207Po sample remains. What is the half life of207Po?

    A 57 hours
    B 11.4 hours
    C 5.7 hours
    D 2.85 hours
    C 0.57 hours

    6.Beta (β) particles are:

    A Negatively charged
    B Positively charged
    C Neutral in charge
    D Non-existent in nature

    7.The half-life of Phosphorus-32 is 14.3 days. How long will it take 16.0 g of this isotope to be reduced to 2.0 g?


    8.Rutherford's α-scattering experiment showed that:

    A Atoms can be destroyed through the use of alpha particles.
    B Atoms consist of protons in a network of electrons.
    C The nucleus is large in comparison to the atom, and is positively charged.
    D The nucleus is small in comparison to the atom, and is positively charged.

    9.The half-life of strontium-90 is approximately twenty-nine years. A sample was found to have 2.25 mg of strontium-90. What mass of strontium-90 must have been present in the sample 116 years ago?

    A 22.5 mg
    B 225 mg
    C 1400 mg
    D 36 mg
    E The mass of strontium-90 116 years ago cannot be determined from the given information.

    10.This individual was not only the first person to earn two separate Nobel prizes, she was also the first woman to ever receive the honor of a Nobel prize for her work on radioactivity. (Physics-1903, Chemistry-1911)

    A Marie Curie
    B Clara Barton
    C Rosalind Franklin
    D Barbara McClintock


    1. B

    2. D

    3. B

    4. B

    5. C

    6. A

    7. 42.8-43

    8. D

    9. D

    10. A