---
title: "A reversible gas-phase reaction is represented by the equation below.  \\[ 2\\,\\text{X(g)} \\rightleftharpoons \\text{X}_2\\text{(g)} \\]  The particulate diagram below represents an equilibrium mixture of \\(\\text{X(g)}\\) and \\(\\text{X}_2\\text{(g)}\\) in a cylinder fitted with a movable piston at an initial volume of \\(1.0\\text{ L}\\) and constant temperature. The piston is then pushed down, instantly reducing the volume of the container to \\(0.50\\text{ L}\\), and the system is allowed to reach a new equilibrium at the same temperature. Which of the following particulate diagrams best represents the system after chemical equilibrium is re-established at the new volume?"
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url: "https://nerd-notes.com/ubq/123887/"
date_modified: "2026-09-28T12:30:55+00:00"
---

# A reversible gas-phase reaction is represented by the equation below.

\[ 2\,\text{X(g)} \rightleftharpoons \text{X}_2\text{(g)} \]

The particulate diagram below represents an equilibrium mixture of \(\text{X(g)}\) and \(\text{X}_2\text{(g)}\) in a cylinder fitted with a movable piston at an initial volume of \(1.0\text{ L}\) and constant temperature. The piston is then pushed down, instantly reducing the volume of the container to \(0.50\text{ L}\), and the system is allowed to reach a new equilibrium at the same temperature. Which of the following particulate diagrams best represents the system after chemical equilibrium is re-established at the new volume?

A reversible gas-phase reaction is represented by the equation below.

\[ 2\,\text{X(g)} \rightleftharpoons \text{X}_2\text{(g)} \]

The particulate diagram below represents an equilibrium mixture of \(\text{X(g)}\) and \(\text{X}_2\text{(g)}\) in a cylinder fitted with a movable piston at an initial volume of \(1.0\text{ L}\) and constant temperature. The piston is then pushed down, instantly reducing the volume of the container to \(0.50\text{ L}\), and the system is allowed to reach a new equilibrium at the same temperature. Which of the following particulate diagrams best represents the system after chemical equilibrium is re-established at the new volume?

![A vertical rectangular cylinder is fitted with a horizontal movable piston near the top. A legend at the upper-right corner indicates: a single open white circle represents one atom of \(\text{X}\); two touching open white circles represent one molecule of \(\text{X}_2\). Inside the full interior volume of the cylinder, there are exactly 4 separate single open white circles and exactly 2 diatomic pairs of touching open white circles, dispersed evenly. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598654-JnENwH.jpg)

- **A.** Diagram A
- **B.** Diagram B
- **C.** Diagram C
- **D.** Diagram D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123887/*