AFCAT: Chemistry MCQs (Practice-Test 28 of 31)

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  1. Suppose that an archeologist has unearthed a human bone. She asks her chemist friend to determine the percentage of carbon-14 present in the bone. The chemist determines that the bone sample contains 67.3% of the carbon-14 present in living tissue. If the half-life of carbon-14 is 5730 years, calculate the age (in years) of the bone.

  2. Carbon-14 undergoes radioactive decay because it has a neutron-to-proton (n/p) ratio that is too large. The GREATEST reduction in the neutron-to-proton ratio of the product nuclide can be achieved by the emission of a (n):

    1. alpha particle.

    2. beta particle.

    3. positron.

    4. neutron.

    5. gamma ray.

  3. Thallium-201 is used in medicine to create images of the heart. A thallium-201 nucleus contains:

    1. 0 neutrons.

    2. 81 neutrons.

    3. 120 neutrons.

    4. 201 neutrons.

    5. None of these.

  4. Uranium-235 undergoes radioactive decay in a series of steps to produce the stable nuclide, lead-207. If the radioactive decay of uranium-235 involves the emissions (in order): Alpha, beta, alpha, beta, alpha, alpha, alpha, alpha, beta, alpha, beta, which of the following nuclides are NOT produced in the decay series?

    1. radon-219

    2. thallium-207

    3. radium-223

    4. proactinium-233

    5. polonium-215

  5. Scientists have recently shown that a sample of cocaine can be traced to its country of origin by measuring the ratio of carbon-13 to nitrogen-15 (both naturally occurring, stable nuclides) in the cocaine sample. Carbon-14 and nitrogen-16, however, do not occur naturally and both of these nuclides undergo radioactive decay by the same process. Which of the following is the most likely type of radioactive decay for carbon-14 and nitrogen-16?

    1. alpha decay

    2. beta decay

    3. positron decay

    4. spontaneous fission

    5. electron capture

  6. Uranium-235 is one of the most common fuels used in nuclear power plants. However, uranium-238 cannot be used as a fuel in a nuclear power plant. Which of the following statements best explains why uranium-238 cannot be used as a fuel?

    1. There is not enough uranium-238 in naturally occurring uranium to use it as a fuel.

    2. It is not possible to construct fuel rods which contain uranium-238.

    3. Uranium-238 does not undergo radioactive decay.

    4. Uranium-238 is not a naturally occurring isotope of uranium.

    5. Uranium-238 does not undergo fission easily enough to be used as a fuel.

  7. Fluorine-18 is one of the radioactive nuclides utilized in Positron Emission Tomography (PET) scans. Fluorine-18 can be synthesized by bombarding oxygen-18 nuclei with hydrogen-1 nuclei, oxygen-18 + hydrogen-1 → fluorine-18 + X What is the identity of the other product, X, in this reaction?

    1. alpha particle

    2. beta particle

    3. positron

    4. neutron

    5. gamma ray

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