---
title: "A rigid, sealed \\(1.0 \\text{ L}\\) container holds a mixture of helium, \\(\\text{He(g)}\\), and argon, \\(\\text{Ar(g)}\\), at thermal equilibrium at \\(300 \\text{ K}\\). A particulate representation of the mixture inside the container is shown in the diagram.  Which of the following statements correctly compares the average kinetic energy of the gas atoms and explains the relative partial pressures of \\(\\text{He(g)}\\) and \\(\\text{Ar(g)}\\) in the container?"
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url: "https://nerd-notes.com/ubq/123673/"
date_modified: "2026-09-28T12:01:57+00:00"
---

# A rigid, sealed \(1.0 \text{ L}\) container holds a mixture of helium, \(\text{He(g)}\), and argon, \(\text{Ar(g)}\), at thermal equilibrium at \(300 \text{ K}\). A particulate representation of the mixture inside the container is shown in the diagram.

Which of the following statements correctly compares the average kinetic energy of the gas atoms and explains the relative partial pressures of \(\text{He(g)}\) and \(\text{Ar(g)}\) in the container?

A rigid, sealed \(1.0 \text{ L}\) container holds a mixture of helium, \(\text{He(g)}\), and argon, \(\text{Ar(g)}\), at thermal equilibrium at \(300 \text{ K}\). A particulate representation of the mixture inside the container is shown in the diagram.

Which of the following statements correctly compares the average kinetic energy of the gas atoms and explains the relative partial pressures of \(\text{He(g)}\) and \(\text{Ar(g)}\) in the container?

![A single square box represents a cross section of a sealed rigid container. A legend to the right defines: small open circle = He atom; large filled circle = Ar atom. Inside the square boundary, there are exactly 6 small open circles and exactly 2 large filled circles, evenly dispersed throughout the interior space without touching each other or the boundaries. The 6 small open circles are positioned at coordinates roughly corresponding to upper-left, upper-middle, center-left, center-right, lower-left, and lower-right. The 2 large filled circles are positioned at roughly upper-right and lower-middle. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790596916-QXEnBu.jpg)

- **A.** The average kinetic energy of \(\text{He}\) atoms is greater than that of \(\text{Ar}\) atoms because \(\text{He}\) atoms have a lower molar mass and a higher average speed; the partial pressure of \(\text{He}\) is greater because there are more \(\text{He}\) atoms in the container.
- **B.** The average kinetic energy of \(\text{He}\) atoms is equal to that of \(\text{Ar}\) atoms because both gases are at the same temperature; the partial pressure of \(\text{He}\) is greater because there are more \(\text{He}\) atoms in the container.
- **C.** The average kinetic energy of \(\text{Ar}\) atoms is greater than that of \(\text{He}\) atoms because \(\text{Ar}\) atoms have a greater molar mass; the partial pressure of \(\text{Ar}\) is greater because heavier atoms exert more force per collision.
- **D.** The average kinetic energy of \(\text{He}\) atoms is equal to that of \(\text{Ar}\) atoms because both gases are at the same temperature; the partial pressure of \(\text{Ar}\) is greater because heavier atoms transfer more momentum during collisions.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123673/*