---
title: "A researcher compares two hypothetical diatomic molecules, \\(\\text{X}_2\\) and \\(\\text{Y}_2\\), using the potential energy curves shown. For each molecule, the potential energy of the separated atoms is defined as zero. Which statement correctly compares the equilibrium bond lengths and bond dissociation energies of the two molecules?"
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url: "https://nerd-notes.com/ubq/119445/"
date_modified: "2026-08-19T12:40:25+00:00"
---

# A researcher compares two hypothetical diatomic molecules, \(\text{X}_2\) and \(\text{Y}_2\), using the potential energy curves shown. For each molecule, the potential energy of the separated atoms is defined as zero. Which statement correctly compares the equilibrium bond lengths and bond dissociation energies of the two molecules?

A researcher compares two hypothetical diatomic molecules, \(\text{X}_2\) and \(\text{Y}_2\), using the potential energy curves shown. For each molecule, the potential energy of the separated atoms is defined as zero. Which statement correctly compares the equilibrium bond lengths and bond dissociation energies of the two molecules?

![Create a grayscale Cartesian graph. Label the horizontal axis Internuclear distance, \(r\) (pm), spanning 0 to 400, and the vertical axis Potential energy (kJ/mol), spanning −500 to +300. Include labeled ticks every 100 units and no gridlines. A legend maps a solid curve to \(\text{X}_2\) and a dashed curve to \(\text{Y}_2\). The solid curve begins above +300 at very small distance, falls steeply to a minimum near \((120,-260)\), then rises gradually toward zero from below. The dashed curve has the same general shape, reaches a minimum near \((180,-420)\), and also approaches zero from below at large distance. Draw a thin horizontal reference line at zero energy. Do not label the minima with coordinates. Keep both curves smooth and clearly distinguishable. No other labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787143225-CpFPSn.jpg)

- **A.** The molecules have the same equilibrium bond length, and \(\text{X}_2\) has the smaller bond dissociation energy, because both curves approach zero at large \(r\) and the minimum for \(\text{X}_2\) is closer to zero.
- **B.** \(\text{X}_2\) has the longer equilibrium bond length and the smaller bond dissociation energy, because its minimum lies farther left and closer to zero.
- **C.** \(\text{X}_2\) has the shorter equilibrium bond length and the greater bond dissociation energy, because its minimum lies farther left and has a less negative potential energy.
- **D.** \(\text{X}_2\) has the shorter equilibrium bond length and the smaller bond dissociation energy, because its minimum lies farther left and has a smaller vertical separation from zero.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119445/*