---
title: "The complete photoelectron spectra of gaseous samples of Element \\(\\text{X}\\) and Element \\(\\text{Y}\\) are shown in the graph. Which of the following identifies the elements and provides the correct explanation for why the rightmost peak of Element \\(\\text{Y}\\) has a lower binding energy than the rightmost peak of Element \\(\\text{X}\\)?"
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url: "https://nerd-notes.com/ubq/120181/"
date_modified: "2026-08-21T16:02:50+00:00"
---

# The complete photoelectron spectra of gaseous samples of Element \(\text{X}\) and Element \(\text{Y}\) are shown in the graph. Which of the following identifies the elements and provides the correct explanation for why the rightmost peak of Element \(\text{Y}\) has a lower binding energy than the rightmost peak of Element \(\text{X}\)?

The complete photoelectron spectra of gaseous samples of Element \(\text{X}\) and Element \(\text{Y}\) are shown in the graph. Which of the following identifies the elements and provides the correct explanation for why the rightmost peak of Element \(\text{Y}\) has a lower binding energy than the rightmost peak of Element \(\text{X}\)?

![A photoelectron spectroscopy graph with two stacked horizontal panels sharing identical logarithmic-scale horizontal axes labeled Binding Energy in units of megajoules per mole, with values decreasing from left to right: 100, 10, 1.0, 0.1. The vertical axes are labeled Relative Number of Electrons. The top panel represents Element X and displays three solid vertical peaks: Peak 1 at 39.6 megajoules per mole with relative height 2; Peak 2 at 2.45 megajoules per mole with relative height 2; Peak 3 at 1.40 megajoules per mole with relative height 3. The bottom panel represents Element Y and displays three solid vertical peaks: Peak 1 at 52.6 megajoules per mole with relative height 2; Peak 2 at 3.04 megajoules per mole with relative height 2; Peak 3 at 1.31 megajoules per mole with relative height 4. No other peaks, gridlines, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787328170-AaAA5l.jpg)

- **A.** Element \(\text{X}\) is \(\text{O}\) and Element \(\text{Y}\) is \(\text{N}\), because the additional proton in oxygen increases the effective nuclear charge, causing all subshells to be held more tightly.
- **B.** Element \(\text{X}\) is \(\text{N}\) and Element \(\text{Y}\) is \(\text{O}\), because the atomic radius of oxygen is greater than that of nitrogen, placing the valence electrons farther from the nucleus.
- **C.** Element \(\text{X}\) is \(\text{N}\) and Element \(\text{Y}\) is \(\text{O}\), because repulsion between the two paired electrons occupying the same \(2p\) orbital in oxygen facilitates electron removal.
- **D.** Element \(\text{X}\) is \(\text{N}\) and Element \(\text{Y}\) is \(\text{O}\), because the core \(1s\) electrons in oxygen provide significantly greater shielding that lowers the effective nuclear charge experienced by the \(2p\) subshell.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120181/*