SAT Subject Physics Practice Question 237: Answer and Explanation
8. Which type of decay ejects the heaviest particle?
A. Alpha decay
B. β– decay
C. β+ decay
D. Electron capture
E. Gamma decay
Correct Answer: A
When a nucleus undergoes alpha decay, it ejects an alpha particle, which is a helium-4 nucleus, composed of 2 protons and 2 neutrons. This is by far the heaviest decay particle that is ejected from a radioactive nucleus.