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1.7: Radioisotopes

  • Page ID
    38587
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    1. Which of the following subatomic particle ratios is important to maintain nuclear stability?
      1. neutron/proton
      2. proton/electron
      3. negatron/neutron
      4. positron/electron
      5. neutron/alpha
    2. Characteristic X-rays are emitted during the nuclear reaction involving:
      1. gamma decay
      2. positron decay
      3. electron capture
      4. negatron decay
      5. none of the above
    3. If decay factors for a radionuclide 8 days and 16 days after the calibration date are 0.9 and 0.8 respectively, what will be the radioactivity of 1 millicurie of this radionuclide 24 days from now?
      1. 0.72 microcurie
      2. 0.072 millicurie
      3. 0.170 millicurie
      4. 0.89 millicurie
      5. 0.72 millicurie
    4. A crystal scintillation detector is primarily used for detecting radionuclides emitting:
      1. positrons
      2. gamma rays
      3. negatrons
      4. X-rays
      5. ultraviolet light
    5. Beta emission is the emission of:
      1. a proton
      2. an electron
      3. a neutron
      4. a ray of light of very short wavelength
      5. an X-ray
    6. Specific activity is the radioactivity as expressed in disintegrations/second per mole of a compound or atom. Which of the following has the highest specific activity?
      1. 125I (t1/2 = 60 days)
      2. 35S (t1/2 = 62 days)
      3. 3H (t1/2 = 12 years)
      4. 14C (t1/2 = 5000 years)
      5. 131I (t1/2 = 8 days)
    7. Gamma emission is the emission of:
      a. a proton
      b. an electron
      c. a neutron
      d. a ray of light of very short wavelength
      e. an X-ray
    8. In the radioactive decay of 3H atom to a 3He atom, the subatomic particle emitted from the nucleus is a (an):
      1. alpha particle
      2. electron (negatron)
      3. positron
      4. gamma ray
      5. neutron
    9. A secondary scintiliator (e.g., POPOP) is used in liquid scintillation counting:
      a. to facilitate dissolution of the sample
      b. to obtain a homogenous scintillation mixture
      c. to enhance the counting efficiency by “wavelength shifting”
      d. as the internal standard
      e. to reduce chemiluminescence
    10. 125I is used as a label because:
      a. it has high specific activity
      b. it is a high-energy emitter
      c. it has a long half-life
      d. all of the above
      e. none of the above

    Use the following Key to answer Questions 11 through 17

    1. 1,2, and 3 are correct
    2. 1 and 3 are correct
    3. 2 and 4 are correct
    4. only 4 is correct
    5. all are correct
    1. 125I-labeled ligands are preferable to 3H-labeled ligands in radioimmunoassays because of:
      1. longer shelf life
      2. higher specific activity
      3. lower cost
      4. gamma-emission
    2. During the course of radioactive decay, a proton is converted to a neutron in:
      1. beta decay
      2. alpha decay
      3. electron capture
      4. positron decay
    3. Scintillation counters measure light pulses. These light pulses are related to:
      1. ionizing radiation
      2. high-energy gamma rays
      3. high-energy beta particles
      4. random electrons
    4. The most commonly encountered radioactive emissions in the hospital laboratory are:
      1. alpha -1 and gamma
      2. alpha -1 and beta
      3. beta + and gamma
      4. beta - and gamma
    5. The most commonly used radioisotope(s) in the chemistry laboratory is/are:
      1. 125I
      2. 35S
      3. 3H
      4. 14C
    6. Radioisotopes are most commonly used to measure in antibody-based competitive assays:
      1. metals
      2. antibodies
      3. electrolytes
      4. antigens
    7. Instrumentation used for detecting and recording beta-emitting isotopes differs from that used for gamma emitters because a beta scintillation counter requires:
      1. a photomultiplier tube
      2. a hollow cathode lamp
      3. a sodium iodide crystal
      4. presence of a fluor
    Answer
    1. a (p. 190)
    2. c (p. 190-191)
    3. e (p. 191-192)
    4. b (p. 194)
    5. b (p. 190)
    6. e (p. 192)
    7. d (p. 191)
    8. b (p. 190)
    9. c (p. 196)
    10. a (p. 192)
    11. c (p. 192)
    12. d (p. 190)
    13. c (p. 194)
    14. d (p. 192)
    15. e (p. 192)
    16. c (p. 189)
    17. d (p. 194-197)

    1.7: Radioisotopes is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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