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

Physics 205B Quiz 7, spring semester 2012
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 neutrons in a nucleus?
(A) α.
(B) β^–.
(C) β⁺.
(D) γ.
(E) (More than one of the above choices.)
(F) (None of the above choices.)

Correct answer (highlight to unhide): (E)

For α decay, a helium nucleus with two protons and two neutrons is emitted from the unstable nucleus; and for β⁺ decay, a neutron transforms into a proton (either by electron capture, or emitting a positron), which also reduces the number of neutrons in the nucleus.

Section 30882
Exam code: quiz07b3Ta
(A) : 3 students
(B) : 5 students
(C) : 0 students
(D) : 0 students
(E) : 17 students
(F) : 0 students

Success level: 68%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.71