Back
Problem 41b,c,d
Predict a likely mode of decay for each unstable nuclide. b. Ru-90 c. P-27 d. Sn-100
Problem 42a,b,d
Predict a likely mode of decay for each unstable nuclide. a. Sb-132 b. Te-139 d. Ba-123
Problem 42c
Predict a likely mode of decay for each unstable nuclide. c. Fr-202
Problem 43
Which nuclide in each pair would you expect to have the longer half-life? a. Cs-113 or Cs-125 b. Fe-62 or Fe-70
Problem 44a,b
Which nuclide in each pair would you expect to have the longer half-life? a. Cs-149 or Cs-139 b. Fe-45 or Fe-52
Problem 45
One of the nuclides in spent nuclear fuel is U-235, an alpha emitter with a half-life of 703 million years. How long will it take for the amount of U-235 to reach 10.0% of its initial amount?
Problem 46
A patient is given 0.050 mg of technetium-99m, a radioactive isotope with a half-life of about 6.0 hours. How long does it take for the radioactive isotope to decay to 1.0⨉10-3 mg? (Assume no excretion of the nuclide from the body.)
Problem 47
A radioactive sample contains 1.55 g of an isotope with a halflife of 3.8 days. What mass of the isotope remains after 5.5 days?
- At 8:00 a.m., a patient receives a 1.5-mg dose of I-131 to treat thyroid cancer. If the nuclide has a half-life of eight days, what mass of the nuclide remains in the patient at 5:00 p.m. the next day? (Assume no excretion of the nuclide from the body.)
Problem 48
Problem 49
A sample of F-18 has an initial decay rate of 1.5⨉105/s. How long will it take for the decay rate to fall to 2.5⨉103/s? (F-18 has a half-life of 1.83 hours.)
- A wooden boat discovered just south of the Great Pyramid in Egypt has a carbon-14 to carbon-12 ratio that is 72.5% of that found in living organisms. How old is the boat?
Problem 51
- A layer of peat beneath the glacial sediments of the last ice age has a carbon-14 to carbon-12 ratio that is 22.8% of that found in living organisms. How long ago was this ice age?
Problem 52
- An ancient skull has a carbon-14 decay rate of 0.85 disintegrations per minute per gram of carbon (0.85 dis/min/g C). How old is the skull? (Assume that living organisms have a carbon-14 decay rate of 15.3 dis/min/g C and that carbon-14 has a half-life of 5715 years.)
Problem 53
Problem 54
A mammoth skeleton has a carbon-14 decay rate of 0.48 disintegration per minute per gram of carbon (0.48 dis/min • g C). When did the mammoth live? (Assume that living organisms have a carbon-14 decay rate of 15.3 dis/min • g C and that carbon- 14 has a half-life of 5715 yr.)
Problem 55
A rock from Australia contains 0.438 g of Pb-206 for every 1.00 g of U-238. Assuming that the rock did not contain any Pb-206 at the time of its formation, how old is the rock?
- A meteor has a Pb-206:U-238 mass ratio of 0.855:1.00. What is the age of the meteor? (Assume that the meteor did not contain any Pb-206 at the time of its formation.)
Problem 56
Problem 57
Write the nuclear reaction for the neutron-induced fission of U-235 to form Xe-144 and Sr-90. How many neutrons are produced in the reaction?
Problem 58
Write the nuclear reaction for the neutron-induced fission of U-235 to produce Te-137 and Zr-97. How many neutrons are produced in the reaction?
Problem 59
Write the nuclear equation for the fusion of two H-2 atoms to form He-3 and one neutron.
Problem 60
Write the nuclear equation for the fusion of H-3 with H-1 to form He-4.
- A breeder nuclear reactor is a reactor in which nonfissionable (nonfissile) U-238 is converted into fissionable (fissile) Pu-239. The process involves bombardment of U-238 by neutrons to form U-239, which then undergoes two sequential beta decays. Write nuclear equations for this process.
Problem 61
- Is the series of nuclear equations to represent the bombardment of Al-27 with a neutron to form a product that subsequently undergoes a beta decay written correctly?
Problem 62
Problem 63
Rutherfordium-257 was synthesized by bombarding Cf-249 with C-12. Write the nuclear equation for this reaction.
- Element 107, now named bohrium, was synthesized by German researchers by colliding bismuth-209 with chromium-54 to form a bohrium isotope and one neutron. Write the nuclear equation that represents this reaction.
Problem 64
Problem 65
If 1.0 g of matter is converted to energy, how much energy is formed?
Problem 66
A typical home uses approximately 1.0⨉103 kWh of energy per month. If the energy came from a nuclear reaction, what mass would have to be converted to energy per year to meet the energy needs of the home?
Problem 67
Calculate the mass defect and nuclear binding energy per nucleon of each nuclide. a. O-16 (atomic mass = 15.994915 amu) b. Ni-58 (atomic mass = 57.935346 amu) c. Xe-129 (atomic mass = 128.904780 amu)
Problem 68
Calculate the mass defect and nuclear binding energy per nucleon of each nuclide. a. Li-7 (atomic mass = 7.016003 amu)
Problem 69
Calculate the quantity of energy produced per gram of U-235 (atomic mass = 235.043922 amu) for the neutron-induced fission of U-235 to form Xe-144 (atomic mass = 143.9385 amu) and Sr-90 (atomic mass = 89.907738 amu) (discussed in Problem 57).
Problem 70
Calculate the quantity of energy produced per mole of U-235 (atomic mass = 235.043922 amu) for the neutron-induced fission of U-235 to produce Te-137 (atomic mass = 136.9253 amu) and Zr-97 (atomic mass = 96.910950 amu) (discussed in Problem 58).