SAT Subject Physics Practice Question 235: Answer and Explanation
6. Which type of decay would cause the number of neutrons in the nucleus to decrease by 1 ?
A. Alpha decay
B. β– decay
C. β+ decay
D. Electron capture
E. Gamma decay
Correct Answer: B
When a nucleus undergoes β– decay, a neutron is converted into a proton and an electron, and the electron is ejected. Because of this, the number of neutrons in the nucleus is decreased by 1.