---
title: "A student analyzes a purified sample of an element using a mass spectrometer and obtains the mass spectrum shown. Based on the mass spectrum, what is the average atomic mass of the element?"
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url: "https://nerd-notes.com/ubq/119170/"
date_modified: "2026-08-19T12:32:42+00:00"
---

# A student analyzes a purified sample of an element using a mass spectrometer and obtains the mass spectrum shown. Based on the mass spectrum, what is the average atomic mass of the element?

A student analyzes a purified sample of an element using a mass spectrometer and obtains the mass spectrum shown. Based on the mass spectrum, what is the average atomic mass of the element?

![A mass spectrum graph with the horizontal axis labeled m/z ranging from 8 to 13 with integer tick marks, and the vertical axis labeled Relative Abundance (%) ranging from 0 to 100 with major tick marks every 20 units. Horizontal gridlines extend from each y-axis tick mark. Two vertical line peaks are shown: one peak at m/z = 10 with a height of 20%, and one peak at m/z = 11 with a height of 80%. No other peaks, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787142761-xNIZXW.jpg)

- **A.** \(10.2 \text{ amu}\), because the peak at \(m/z = 10\) represents the isotope with the greater relative abundance.
- **B.** \(10.8 \text{ amu}\), because the isotope with a mass of \(11 \text{ amu}\) is four times as abundant as the isotope with a mass of \(10 \text{ amu}\).
- **C.** \(10.5 \text{ amu}\), because the average atomic mass is the simple unweighted mean of the masses of the two isotopes.
- **D.** \(11.0 \text{ amu}\), because the average atomic mass equals the mass of the peak with the greatest relative abundance.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119170/*