---
title: "A student analyzes a copper-based alloy known to contain \\(\\text{Cu}\\) and exactly one additional metal, \\(X\\), which is either \\(\\text{Co}\\) or \\(\\text{Ni}\\). Because the valence-region peaks of the metals overlap, the student examines resolved core-level peaks that are absent from the spectrum of pure \\(\\text{Cu}\\). Reference data are shown below.  | Metal standard | \\(E_{3p}\\) \\((\\text{eV})\\) | \\(E_{3s}\\) \\((\\text{eV})\\) | |—|—:|—:| | \\(\\text{Co}\\) | \\(59.0\\) | \\(101.0\\) | | \\(\\text{Ni}\\) | \\(66.0\\) | \\(111.0\\) |  The spectrometer may add the same unknown constant offset to every reported binding energy in a spectrum. Tests with standards indicate that alloying changes \\(E_{3s}-E_{3p}\\) from the pure-metal value by no more than \\(0.5\\ \\text{eV}\\). Peak areas also depend on the concentration of each metal and the instrumental response to each subshell. Which additional PES result would be sufficient to identify \\(X\\) as \\(\\text{Co}\\) rather than \\(\\text{Ni}\\)?"
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url: "https://nerd-notes.com/ubq/120046/"
date_modified: "2026-08-21T08:40:55+00:00"
---

# A student analyzes a copper-based alloy known to contain \(\text{Cu}\) and exactly one additional metal, \(X\), which is either \(\text{Co}\) or \(\text{Ni}\). Because the valence-region peaks of the metals overlap, the student examines resolved core-level peaks that are absent from the spectrum of pure \(\text{Cu}\). Reference data are shown below.

| Metal standard | \(E_{3p}\) \((\text{eV})\) | \(E_{3s}\) \((\text{eV})\) |
|—|—:|—:|
| \(\text{Co}\) | \(59.0\) | \(101.0\) |
| \(\text{Ni}\) | \(66.0\) | \(111.0\) |

The spectrometer may add the same unknown constant offset to every reported binding energy in a spectrum. Tests with standards indicate that alloying changes \(E_{3s}-E_{3p}\) from the pure-metal value by no more than \(0.5\ \text{eV}\). Peak areas also depend on the concentration of each metal and the instrumental response to each subshell. Which additional PES result would be sufficient to identify \(X\) as \(\text{Co}\) rather than \(\text{Ni}\)?

A student analyzes a copper-based alloy known to contain \(\text{Cu}\) and exactly one additional metal, \(X\), which is either \(\text{Co}\) or \(\text{Ni}\). Because the valence-region peaks of the metals overlap, the student examines resolved core-level peaks that are absent from the spectrum of pure \(\text{Cu}\). Reference data are shown below.

| Metal standard | \(E_{3p}\) \((\text{eV})\) | \(E_{3s}\) \((\text{eV})\) |
|---|---:|---:|
| \(\text{Co}\) | \(59.0\) | \(101.0\) |
| \(\text{Ni}\) | \(66.0\) | \(111.0\) |

The spectrometer may add the same unknown constant offset to every reported binding energy in a spectrum. Tests with standards indicate that alloying changes \(E_{3s}-E_{3p}\) from the pure-metal value by no more than \(0.5\ \text{eV}\). Peak areas also depend on the concentration of each metal and the instrumental response to each subshell. Which additional PES result would be sufficient to identify \(X\) as \(\text{Co}\) rather than \(\text{Ni}\)?

- **A.** The \(X\)-derived \(3p\) peak is reported at \(59.0\ \text{eV}\); this absolute value equals the \(\text{Co}\) standard value in the table.
- **B.** The \(X\)-derived \(3s\) and \(3p\) peaks are separated by \(42.0\pm0.2\ \text{eV}\); a uniform energy offset cancels when the separation is calculated.
- **C.** The \(X\)-derived \(3s\) peak occurs at higher binding energy than its \(3p\) peak; the \(3s\) electrons penetrate closer to the nucleus.
- **D.** The \(X\)-derived \(3d\) peak has a smaller integrated area than the \(\text{Cu}\) \(3d\) peak; fewer detected electrons are assigned to \(X\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120046/*