---
title: "A gas cylinder contains a mixture of only helium gas, \\(\\text{He}\\) (\\(\\text{molar mass } 4.0\\text{ g/mol}\\)), and argon gas, \\(\\text{Ar}\\) (\\(\\text{molar mass } 40.0\\text{ g/mol}\\)). A \\(2.00\\text{ mol}\\) sample of this mixture has a total mass of \\(26.0\\text{ g}\\). What is the mole fraction of \\(\\text{He}\\) in the mixture?"
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url: "https://nerd-notes.com/ubq/119606/"
date_modified: "2026-08-21T08:11:44+00:00"
---

# A gas cylinder contains a mixture of only helium gas, \(\text{He}\) (\(\text{molar mass } 4.0\text{ g/mol}\)), and argon gas, \(\text{Ar}\) (\(\text{molar mass } 40.0\text{ g/mol}\)). A \(2.00\text{ mol}\) sample of this mixture has a total mass of \(26.0\text{ g}\). What is the mole fraction of \(\text{He}\) in the mixture?

A gas cylinder contains a mixture of only helium gas, \(\text{He}\) (\(\text{molar mass } 4.0\text{ g/mol}\)), and argon gas, \(\text{Ar}\) (\(\text{molar mass } 40.0\text{ g/mol}\)). A \(2.00\text{ mol}\) sample of this mixture has a total mass of \(26.0\text{ g}\). What is the mole fraction of \(\text{He}\) in the mixture?

- **A.** \(0.25\)
- **B.** \(0.50\)
- **C.** \(0.75\)
- **D.** \(0.85\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119606/*