Question

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 __________.

Answer 1

The most abundant nuclide in a sample of uranium-containing rock from the given decay series will be 238U (uranium-238).

Step-by-step explanation:

The most abundant nuclide in a sample of uranium-containing rock from the given decay series will be 238U (uranium-238).

In the decay series mentioned in the question, uranium-238 decays into thorium-234, which then decays into protactinium-234. Finally, protactinium-234 decays back into uranium-234.

Since uranium-238 is the starting point of the decay series,

it will be the most abundant nuclide in the sample. The subsequent daughter nuclides, thorium-234 and protactinium-234, will be present in smaller quantities until equilibrium is reached, where the rates of production and decay of each nuclide in the series are equal.

Answer 2

1. C: 31/14 Si becomes 31/15 because a nuetron

2. A: 238 92U because the very long half-life means a very small rate of decay

3. D: Charge conservation is not satisfied

4. B: of the four nuclear decay processes only the α-decay changes the baryon number and does so in increments of four

Step-by-step explanation:

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