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Radioactive Decay quiz #1

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Terms in this set (40)

  • Which radioactive element has the lowest atomic number?
    Technetium (atomic number 43) is the radioactive element with the lowest atomic number.
  • What does it mean when we say that a nucleus undergoes radioactive decay?
    It means the unstable nucleus emits particles or energy, changing into a different element or isotope.
  • Radium decays to form radon. Which equation correctly describes this decay?
    226Ra → 222Rn + 4He (alpha decay).
  • What nuclide is formed when Th-230 undergoes alpha emission?
    Ra-226 is formed when Th-230 undergoes alpha emission.
  • Lead-210 decays by emitting a beta particle. What nuclide is produced?
    Bismuth-210 is produced when lead-210 emits a beta particle.
  • Which radioisotope is used to determine the age of once-living organisms?
    Carbon-14 is used for dating once-living organisms.
  • What nuclide is formed when Na-22 undergoes positron emission?
    Neon-22 is formed when Na-22 undergoes positron emission.
  • What are the radioactive elements with atomic numbers from 90 to 103 called?
    They are called the actinides.
  • Tin-126 undergoes electron capture. What will be the mass number of the product of this decay?
    The mass number remains 126 after electron capture.
  • What is the mode of radioactive decay of Al-28?
    Al-28 undergoes beta minus decay.
  • A radioactive decay equation is illustrated. Which radioactive emission is a product of this decay?
    The emission shown as a product could be alpha, beta, or gamma, depending on the equation.
  • What happens during nuclear fission?
    Nuclear fission splits a large nucleus into smaller nuclei, releasing energy.
  • What does a Geiger counter measure?
    A Geiger counter measures radioactivity (the rate of radioactive decay).
  • What is the half-life of uranium-234?
    The half-life of uranium-234 is about 245,500 years.
  • What is the radioactivity of a sample of sodium-24 after one half-life?
    After one half-life, the radioactivity is reduced to half its original value.
  • Which type of radioactive decay would you expect Fe-60 to undergo?
    Fe-60 undergoes beta minus decay.
  • Why is it important that radioisotopes used in diagnostic tests have short half-lives?
    Short half-lives minimize radiation exposure to patients.
  • What is characteristic of a nuclear reaction?
    Nuclear reactions change the identity of elements by altering the number of protons.
  • Which radioactive emission is a product of this decay?
    The product could be an alpha, beta, or gamma particle, depending on the decay type.
  • Name an element that is radioactive and synthetic.
    Elements like seaborgium (Sg) are radioactive and synthetic.
  • What is the process of breaking a large nucleus into two smaller nuclei called?
    This process is called nuclear fission.
  • Why do scientists specifically use carbon-14 for radioactive dating?
    Carbon-14 is used because it is present in living organisms and has a suitable half-life for dating.
  • What is the process in which an unstable atomic nucleus emits charged particles or energy or both?
    This process is called radioactive decay.
  • Radon-220 decays to polonium-216. What particle is emitted?
    An alpha particle is emitted.
  • By what process does thorium-230 decay to radium-226?
    Thorium-230 decays to radium-226 by alpha emission.
  • Uranium-238 decays by alpha emission. What is the mass number of the resulting element?
    The mass number is 234 after alpha emission.
  • How will beta decay affect the atomic number and mass number of the atom?
    Beta decay increases atomic number by 1; mass number remains unchanged.
  • What part of an atom undergoes change during radioactive decay?
    The nucleus undergoes change during radioactive decay.
  • Lead-212 decays into bismuth-212 by emitting which particle?
    A beta particle is emitted.
  • What happens when nuclear fission occurs?
    A large nucleus splits into smaller nuclei, releasing energy and neutrons.
  • Which describes radioactive decay of a substance?
    Radioactive decay is the spontaneous emission of particles or energy from an unstable nucleus.
  • Which parent nuclide would give rise to the daughter nuclide Na-20 by positron emission?
    Mg-20 would give rise to Na-20 by positron emission.
  • What is the measure of radioactive decay rate?
    The rate is measured as activity, often in becquerels or curies.
  • Which of these elements was not found by Curie to be radioactive?
    Curie did not find uranium to be radioactive; it was already known.
  • What is the change in atomic number when an atom emits a beta particle?
    The atomic number increases by 1.
  • Which of these is true for a fission reaction?
    Fission reactions release large amounts of energy and produce smaller nuclei.
  • Why can radioactive elements be used to determine the ages of rocks?
    Their predictable decay rates allow calculation of elapsed time since formation.
  • What are typical products of nuclear fission?
    Smaller nuclei and free neutrons are typical products.
  • What happens during radioactive decay?
    An unstable nucleus emits particles or energy, changing into a different element or isotope.
  • Consider the nuclear equation below. What is the nuclide symbol of X?
    X is determined by balancing atomic and mass numbers in the equation.