Competitive Exams: Chemistry MCQs (Practice-Test 25 of 31)

  1. Which one of the following types of particles is the MOST highly penetrating to biological tissues?

    1. alpha particles

    2. beta particles

    3. positrons

    4. neutrons

    5. electrons

  2. In lecture, you observed a radioactive plate that contained uranium oxide as a pigment (i.e.. “Fiestaware” ). What color was the plate?

    1. yellow

    2. purple

    3. white

    4. orange

    5. green

  3. An ancient wood sculpture was determined to be 2380 years old. Calculate the percentage of the carbon-14 originally present in the wood that remains today. For carbon-14: t1/2 = 5730 years.

  4. Americium-241 is the radioactive isotope that is used in smoke detectors. Americium-241 undergoes alpha decay with a half-life of 458 years. What is the product nuclide that is produced when americium-241 radioactively decays?

    1. neptunium-237

    2. curium-241

    3. plutonium-241

    4. americium-240

    5. plutonium-240

  5. Positron emission tomography (PET) scans are used medicinally to diagnose certain biological disorders. The most common radioactive isotope used in this procedure is fluorine-18, which is a positron emitter. In a PET scan, which one of the following species is actually measured in order to create a three-dimensional image of the afflicted organ?

    1. alpha particles

    2. beta particles

    3. gamma rays

    4. positrons

    5. neutrons

  6. In lecture, you observed a desiccator that was used for many years to store radioactive radium compounds. What color was the desiccator?

    1. yellow

    2. orange

    3. purple

    4. green

    5. black

  7. The radioactive nuclide, iodine-131, is used medicinally as a radiotracer for the diagnosis and treatment of illnesses associated with the thyroid gland. If the rate constant for decay of iodine-131 is 9.9 × 10 − 7 s − 1, calculate the half-life (in s) of iodine-131.

  8. Calculate the binding energy per nucleon in millions of electron volts (MeV) for nitrogen-15. The atomic mass of nitrogen-15 is 15.00011 amu.

  9. What is the final, stable nuclide, X, if radon-222 decays by the emission of four alpha particles and four beta particles?

    1. tungsten-206

    2. tungsten-214

    3. platinum-202

    4. platinum-210

    5. lead-206

  10. An archeologist unearths a bone sample and wants to know the age of the bone. Her chemist friend determines that 41.7% of the initial amount of carbon-14 in the bone sample has decayed. If the half-life of carbon-14 is 5730 years, the age of the bone is:

    1. 4460 years

    2. 5730 years

    3. 7230 years

    4. 10200 years

    5. 11460 years

  11. Which of the following characteristics is/are important considerations for radiotracers that will be used for diagnosing illness in the body?

    1. The radiotracer should have a short half-life.

    2. The radiotracer should localize in a certain part of the body.

    3. The radiotracer should produce radiation that can be detected externally.

    4. Both a and c

    5. All the three statements

  12. When a nuclide is assembled from its constituent protons, neutrons, and electrons, there is about a 1% decrease in mass. When a chemical compound is similarly made from its constituent elements there is no discernible change in mass. The best reason for this difference is that:

    1. chemical reactions are intrinsically different from nuclear reactions.

    2. the formation of a nuclide from its constituents is always exothermic whereas the formation of a compound from the elements can be either exothermic or endothermic.

    3. Einstein's equation, E = mc2, applies to nuclei but not to molecules.

    4. chemical reactions release far less energy than nuclear reactions and so the mass change is too small to observe.

    5. mass is conserved in chemical reactions but is not conserved in nuclear reactions.

  13. The mass of chlorine-37 is 36.96590 amu. The binding energy per nucleon of chlorine-37 is:

    1. -1.41 × 10 − 12 J/nucleon

    2. 1.29 × 10 − 12 J/nucleon

    3. 1.37 × 10 − 12 J/nucleon

    4. 5.08 × 10 − 11 J/nucleon

    5. 5.08 × 10 − 8 J/nucleon

  14. The only stable nuclide with A = 35 is chlorine-35. Which of the following equations correctly describe the process by which phosphorus-35 decays to chlorine-35?

    1. phosphorus-35 → chlorine-35 + beta particle

    2. phosphorus-35 → sulfur-35 + beta particle sulfur-35 → chlorine-35 + beta particle

    3. phosphorus-35 → silicon-35 + beta particle silicon-35 → chlorine-35 + beta particle

    4. phosphorus-35 → chlorine-35 + positron

    5. phosphorus-35 + e → sulfur-35

    sulfur-35 + e → chlorine-35

  15. A freshly prepared sample of yttrium-90 undergoes 7.6 × 105 disintegrations per minute (dpm) at a certain time. Exactly 14 days later, the same sample undergoes 1.6 × 104 dpm. The half-life of yttrium-90 is:

    1. 0.20 day

    2. 2.5 day

    3. 2.7 day

    4. 3.8 day

    5. 14 day