Why is 14C radioactive?
  1. It has too many neutrons.
  2. It has too many protons.
  3. It needs to reduce its nuclear charge to be stable.
  4. It needs to increase its nuclear charge to be stable.
  5. Nitrogen has more thermodynamic degrees of freedom.



166W (Z=74) decays via alpha decay with a half-life of 16 seconds. What is the final product?
  1. 162Hf (Z=72)
  2. 164Hf (Z=72)
  3. 162W (Z=74)
  4. 162Os (Z=76)
  5. 170Os (Z=76)



After spontaneous fission, how does the mass of all of the products compare to the mass of the initial consituents?
  1. The products have more mass.
  2. The products have less mass.
  3. They should be the same.
  4. It depends on the reaction.



235U decays via alpha decay with a half life of 704 million years. What is the immediate daughter product?
  1. 231U
  2. 231Th
  3. 233U
  4. 233Th
  5. 233Pa



14C decays via beta decay with a half life of 5730 years. What is the decay product?
  1. 14N
  2. 14B
  3. 13C
  4. 12C
  5. 13B



11C decays by positron decay and is used as a radioactive source in positron emission spectroscopy (PET). It has a half life of about 20 minutes. How long will a sample last until it's radioactive signal as dropped to 1/16 of its original strength?
  1. 75 seconds
  2. 320 minutes
  3. 80 minutes
  4. 160 minutes
  5. other



You have two lead blocks for shielding gamma radiation from a nuclear reaction. If the second block is twice as thick as the first, how does the number of gamma rays penetrating the blocks compare in the two cases?
  1. It will be the same.
  2. There will be half as many gamma rays penetrating the thicker block.
  3. There will be twice as many gamma rays penetrating the thicker block.
  4. There will be 1/e as many gamma rays penetrating the thicker block.
  5. There will be e-2 as many gamma rays penetrating the thicker block.



I measure the cross section for a nuclear reaction by shining a beam of 5 x 1012 neutrons/m2/s on a sample containing 1016 target nuclei. If I produce 5 reactions per second, what is the cross section?
  1. 10-28 m2
  2. 1028 m2
  3. 10-14 m2
  4. 1014 m2
  5. 1.6 x 10-24 m2



Why can't we make a nucleus out of just neutrons?
  1. The nuclear force for neutrons isn't attractive.
  2. You can't get neutrons close to each other very easily.
  3. Neutrons tend to decay into protons, which can go to a lower energy state.
  4. There is a stronger attraction between neutrons and protons, than just between neutrons.
  5. We can.



An important nuclear decay process is called electron capture. In this process, an atomic electron is captured by a proton in the nucleus, turning the proton into a neutron (and emitting another particle we'll learn about later). An electron in which of the following states is most likely to be captured in the nucleus?
  1. n=1, l=0, m=0
  2. n=2, l=1, m=0
  3. n=3, l=2, m=-2
  4. n=4, l=0, m=0
  5. n=5, l=3, m=-2