---
title: "A heavy, unstable parent nucleus with mass number \\(A\\) and atomic number \\(Z\\) undergoes alpha decay to form a daughter nucleus. Which of the following correctly identifies the changes in the mass number and atomic number of the daughter nucleus relative to the parent, as well as the physical reason heavy nuclei are prone to alpha decay?"
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url: "https://nerd-notes.com/ubq/117144/"
date_modified: "2026-08-04T06:44:47+00:00"
---

# A heavy, unstable parent nucleus with mass number \(A\) and atomic number \(Z\) undergoes alpha decay to form a daughter nucleus. Which of the following correctly identifies the changes in the mass number and atomic number of the daughter nucleus relative to the parent, as well as the physical reason heavy nuclei are prone to alpha decay?

A heavy, unstable parent nucleus with mass number \(A\) and atomic number \(Z\) undergoes alpha decay to form a daughter nucleus. Which of the following correctly identifies the changes in the mass number and atomic number of the daughter nucleus relative to the parent, as well as the physical reason heavy nuclei are prone to alpha decay?

- **A.** Mass number \(A\) decreases by 2, atomic number \(Z\) decreases by 4; heavy nuclei are unstable because the strong nuclear force range decreases as the nucleus expands.
- **B.** Mass number \(A\) decreases by 4, atomic number \(Z\) decreases by 2; heavy nuclei are unstable because long-range electrostatic repulsion between protons grows faster with size than short-range strong force attraction.
- **C.** Mass number \(A\) decreases by 4, atomic number \(Z\) decreases by 2; heavy nuclei are unstable because the strong nuclear force becomes repulsive at large distances.
- **D.** Mass number \(A\) decreases by 2, atomic number \(Z\) decreases by 2; heavy nuclei are unstable because the weak nuclear force repels positively charged protons.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117144/*