試題詳解

13. Which of the following statements about nuclear reaction and stability is correct? (Z is the atomic number.)
(A) As Z increases, nuclides need a smaller neutron-to-proton ratio for stability.
(B) Nuclides with small Z values are often observed to be a-particle producers.
(C) A radioactive nuclide that decays from 2.00 × 1010 atoms to 2.50 × 10º atoms in 30.0 min has a half-life of 15.0 min.
(D) Both the radioactive processes of positron production and electron capture increase the neutron-to-proton ratio.
(E) If less than one neutron from each fission event causes another fission event, the fission situation is described as supercritical.