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Radioactive Decay quiz #2

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Terms in this set (38)

  • Which material undergoes radioactive decay?
    Radioactive isotopes (radioisotopes) undergo radioactive decay.
  • Which represents the balanced equation for the beta minus emission of phosphorus-32?
    32P → 32S + β⁻
  • Which radioactive isotope would take the least amount of time to become stable?
    The isotope with the shortest half-life becomes stable fastest.
  • What processes involve radionuclides or radioisotopes?
    Radioactive dating, medical imaging, and cancer treatment involve radioisotopes.
  • What is the decay mode of the following decay? 137Cs → 137Ba + ?
    Beta minus decay (emission of a beta particle).
  • Which type of radioactive decay would produce a decay particle that would move along path a?
    Alpha decay produces an alpha particle.
  • The nuclide Rn-204 is the daughter nuclide resulting from the alpha decay of what parent nuclide?
    Po-208 is the parent nuclide (208Po → 204Rn + α).
  • The isotope Zn-65 undergoes what mode of radioactive decay?
    Zn-65 undergoes beta minus decay.
  • What particle is emitted in the radioactive decay 27Si → 27Al?
    A beta particle is emitted.
  • An unstable isotope of Re-191 is a beta producer. What is the other product of the reaction?
    Osmium-191 (191Os) is produced along with a beta particle.
  • A radioactive sample contains 10,000 atoms. After two half-lives, how many atoms remain undecayed?
    2,500 atoms remain undecayed after two half-lives.
  • What nuclide undergoes neutron emission to form Br-79?
    Br-80 undergoes neutron emission to form Br-79.
  • What kind of decay must magnesium-23 undergo to generate sodium-23?
    Magnesium-23 must undergo beta minus decay.
  • What nucleus decays by successive beta emissions?
    A nucleus with excess neutrons, such as uranium-238, can decay by successive beta emissions.
  • What is the decay mode of the following decay? 222Rn → 218Po + ?
    Alpha decay (emission of an alpha particle).
  • Which phrase describes one characteristic of radioactive elements?
    They have unstable nuclei that spontaneously emit radiation.
  • Which statement describes what is gained or lost during radioactive decay?
    Particles or energy are emitted or absorbed, changing the nucleus.
  • The use of radioisotope imaging is best suited for which procedure?
    Medical diagnostic imaging, such as PET scans.
  • Why do radioactive waste containers need to last for thousands of years without corroding?
    To safely contain long-lived radioactive materials and prevent environmental contamination.
  • How many grams of seaborgium-266 will be left after 90 seconds?
    This depends on the half-life; if the half-life is 30 seconds, 1/8 of the original amount remains after 90 seconds.
  • Which would result in radioactive decay? Check all that apply.
    Unstable nuclei, excess neutrons or protons, and high atomic numbers can result in radioactive decay.
  • When does the radioactive decay of a radioisotope stop? Give one example.
    Decay stops when a stable (non-radioactive) nucleus is formed, e.g., lead-206 from uranium decay.
  • What fraction of a Sr-90 sample remains unchanged after 87.3 years?
    One half remains after one half-life (Sr-90 half-life is 28.8 years; 87.3/28.8 ≈ 3 half-lives, so 1/8 remains).
  • Which of these is a common radioactive tracer used in medicine?
    Technetium-99m is a common radioactive tracer.
  • Complete the following nuclear decay process: 238U → 4He + ___
    234Th (thorium-234) is the other product.
  • Radioactive tracers _________.
    Are used to track chemical processes or diagnose medical conditions.
  • The equation below is best described as ___________. 198Hg → 198Au + e⁻
    Beta minus decay.
  • What percentage of a radioactive species would be found as daughter material after five half-lives?
    About 97% would be daughter material after five half-lives.
  • If 1 g of radium-226 has an activity of 1 curie, what is the activity of 2 g of radium-226?
    2 curies.
  • Radioactive decay is likely to occur when ...
    The nucleus is unstable due to excess neutrons or protons.
  • Which radioactive element has the lowest atomic number?
    Technetium (atomic number 43).
  • A radioactive sample contains 10,000 atoms. After two half-lives, how many atoms remain undecayed?
    2,500 atoms remain.
  • Which statement accurately describes radioactive dating?
    Radioactive dating uses predictable decay rates to estimate the age of materials.
  • A container holds a pure sample of a radioactive substance with a half-life of 2 hours. How much remains after 6 hours?
    After 6 hours (3 half-lives), 1/8 of the original sample remains.
  • An element of atomic number 88 decays radioactively to an element of atomic number 82. What type of decay occurred?
    Alpha decay (loss of 2 protons).
  • Identify the product of radioactive decay and classify the given nuclear reactions accordingly.
    Products are determined by the type of decay: alpha (He-4), beta (electron), positron, or gamma (energy).
  • The graph shows the decay of a radioactive sample over days. Select the data point at one half-life.
    The data point where half the original sample remains is at one half-life.
  • If you have 100 grams of a radioactive isotope with a half-life of 10 years, how much remains after 20 years?
    25 grams remain after 20 years (two half-lives).