SAT Subject Physics Practice Question 238: Answer and Explanation

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Question: 238

9. Which type of decay would cause the atomic number of the nucleus to increase?

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 protons in the nucleus—the atomic number—is increased by 1.

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