Physics quiz question: decay(s) for decreasing proton number

Physics 205B Quiz 7, spring semester 2013
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Multiple-Choice Question 29.1

Which decay mode decreases the number of protons in a nucleus?
(A) α.
(B) β^–.
(C) β⁺.
(D) electron capture.
(E) γ.
(F) (More than one of the above choices.)
(G) (None of the above choices.)

Correct answer: (F)

For α decay, a helium nucleus with two protons and two neutrons is emitted from the unstable nucleus; for β⁺ decay, a proton is converted into a neutron (and emits a positron and a neutrino); for electron capture, a proton combines with an electron to convert into a neutron (and emits a neutrino); all of these processes decrease the number of protons in a nucleus.

For γ decay a photon is emitted, and there is no change in the number of protons (or neutrons) in the nucleus. For β^- decay, a neutron transforms into a proton (and emits an electron and an antineutrino), which increases the number of protons in the nucleus.

Section 30882
Exam code: quiz07f3yN
(A) : 1 student
(B) : 6 students
(C) : 3 students
(D) : 0 students
(E) : 0 students
(F) : 22 students
(G) : 0 students

Success level: 69%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.21