Chapter 27 review

    Quantitative problems
      Section 27.2
      1. If you start with 1,280 atoms of an unstable isotope, how many half-lives will it take (on average) for you to end up with 10 or fewer atoms of the original isotope?

      2. Through what decay process does uranium-238 decay to thorium-234?

      3. Easy Cesium-137 undergoes beta decay.
        1. Write down the nuclear reaction equation including the reactants and the products.
        2. This decay is evidence of what fundamental force?

      4. Easy An atom undergoes beta decay. If the product is nickel-60, what was the original isotope?

      5. Easy Seaborgium-271 undergoes alpha decay. Write down the nuclear reaction equation.

      6. Easy An atom undergoes alpha decay, producing bismuth-207. Write down the nuclear reaction equation.

      7. Challenging A laboratory technician starts with a mass of 2.79 kg of radioactive polonium-197 that has a half-life of 53.6 s. It is enclosed in a 23.9 kg lead case. How long will it take for the polonium-197 to decay radioactively to 0.78% of the original amount?

      8. Easy An archeologist measured the mass of carbon-14 in a fossil to be 1 g, and then calculated the age of the fossil to be 28,650 years old. What was the original mass of carbon-14 in the fossil 28,650 years ago?

      9. Medium Krypton-85 decays with a half-life of 10.8 years. If we start out with 50 mg of krypton-85, how much would remain after 30 years?

      10. Challenging A sample that contains iron-59 is measured with a radiation counter, which records about 11 decays per minute. After 20 days the same sample is measured to give about 8 decays per minute. Calculate the half-life of iron-59 in days.

      11. Easy The radioactive decay of polonium-210 is described by the following equation:

        P 84 210 o→ P ? ? b+ X 2 4 where X is the particle emitted upon decay. Identify the correct isotope of lead and type of decay.
        1. lead-206; alpha decay
        2. lead-208; alpha decay
        3. lead-206; beta decay
        4. lead-208; positron emission


        Section 27.3
        1. Easy The product of one fission reaction for a uranium-235 atom is given by the following reaction equation:

          U 92 235 + n 0 1 → N 60 143 d+ Z 40 90 r+3 n 0 1 +?e
          How many electrons are produced by the reaction?

        2. Easy What is the type and the unknown product of the following nuclear reaction equation?

          H 1 2 + H 1 3 → H 2 4 e+X?+energy
          1. fusion; proton
          2. fusion; neutron
          3. fission; neutron
          4. fusion; two neutrons


        3. Medium When a neutron hits the nucleus of a plutonium-239 atom, the subsequent nuclear reaction creates cesium-148, a mystery isotope, and three neutrons. Write down the nuclear reaction equation and determine the mystery isotope.

        4. Easy For the reaction:             

          H 2 3 e+ H 1 1 → X Z A + e 1 0
          what is the unknown X Z A ?
          1. H 1 2
          2. H 2 3 e
          3. H 2 4 e
          4. L 3 5 i


        Section 27.4
        1. Medium A small nuclear power plant has a set of fuel rods that weigh 50.0 kg. After some time, the fuel rods weigh 49.9 kg. How much energy did the fuel rods release?

        2. Medium To produce energy in nuclear power plants, uranium-235 undergoes fission according to the equation

          n 0 1 + U 92 235 → M 42 99 o+ S 50 ? n+2 n 0 1 +energy
          Determine the missing value.

        3. Medium The nuclear reaction n 0 1 + U 92 235 → B 56 144 a+ K 36 89 r+3 n 0 1 releases around 200 MeV of energy. Convert this energy to joules.

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