1. Which of the following transformations is an example of a β−-decay?

2.The unstable uranium nuclide 238 92U has a half-life of 4.5 billion years and decays into the thorium nuclide 234 90Th. The thorium daughter nuclide has a half-life of 24.1 days and decays into the protactinium nuclide 234 91Pa, which has a half-life of 6.75 hours and decays into 234 90U, whose half-life is 245 thousand years. In a sample of uranium-containing rock, of the four nuclides the most abundant will be __________.

3. The beta minus decay process 13 7N→13 6C+β−+ν¯¯¯ is proposed in which nitrogen’s proton becomes a neutron. The process is not possible because:

4.The fact that the relative abundance is greater for elements in which the total number of protons and neutrons is a multiple of two is because __________.