---
title: "A student obtains two separate pure isotopic samples: Sample 1 consists of \\(10.0\\text{ g}\\) of pure \\(^{63}\\text{Cu}\\), and Sample 2 consists of \\(10.0\\text{ g}\\) of pure \\(^{65}\\text{Cu}\\). Which of the following statements correctly compares the number of atoms in Sample 1 to the number of atoms in Sample 2, and provides the valid justification?"
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url: "https://nerd-notes.com/ubq/120154/"
date_modified: "2026-08-21T16:02:36+00:00"
---

# A student obtains two separate pure isotopic samples: Sample 1 consists of \(10.0\text{ g}\) of pure \(^{63}\text{Cu}\), and Sample 2 consists of \(10.0\text{ g}\) of pure \(^{65}\text{Cu}\). Which of the following statements correctly compares the number of atoms in Sample 1 to the number of atoms in Sample 2, and provides the valid justification?

A student obtains two separate pure isotopic samples: Sample 1 consists of \(10.0\text{ g}\) of pure \(^{63}\text{Cu}\), and Sample 2 consists of \(10.0\text{ g}\) of pure \(^{65}\text{Cu}\). Which of the following statements correctly compares the number of atoms in Sample 1 to the number of atoms in Sample 2, and provides the valid justification?

- **A.** Sample 1 contains a greater number of atoms than Sample 2 because each \(^{63}\text{Cu}\) atom has a smaller mass than each \(^{65}\text{Cu}\) atom, so a \(10.0\text{ g}\) sample contains a greater number of moles of \(^{63}\text{Cu}\).
- **B.** Sample 1 contains a greater number of atoms than Sample 2 because \(^{63}\text{Cu}\) has fewer protons in its nucleus, resulting in less electron shielding and allowing more atoms to exist in the sample.
- **C.** Sample 1 contains a smaller number of atoms than Sample 2 because \(^{63}\text{Cu}\) has a lower molar mass than \(^{65}\text{Cu}\), so fewer individual atoms are required to reach a total mass of \(10.0\text{ g}\).
- **D.** Sample 1 contains the same number of atoms as Sample 2 because both samples have an identical mass of \(10.0\text{ g}\) and consist of the same chemical element.

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