---
title: "A student prepares five standard solutions of \\(\\text{Co(NO}_3\\text{)}_2\\text{(aq)}\\) and measures the absorbance of each at a wavelength of \\(510\\text{ nm}\\) using a cuvette with a path length of \\(1.0\\text{ cm}\\). The resulting calibration plot is shown below. The student then measures an unknown \\(\\text{Co(NO}_3\\text{)}_2\\text{(aq)}\\) sample under the same conditions and records an absorbance of \\(0.30\\). Based on the calibration plot, what is the concentration of \\(\\text{Co(NO}_3\\text{)}_2\\text{(aq)}\\) in the unknown sample?"
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url: "https://nerd-notes.com/ubq/119262/"
date_modified: "2026-08-19T12:39:34+00:00"
---

# A student prepares five standard solutions of \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) and measures the absorbance of each at a wavelength of \(510\text{ nm}\) using a cuvette with a path length of \(1.0\text{ cm}\). The resulting calibration plot is shown below. The student then measures an unknown \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) sample under the same conditions and records an absorbance of \(0.30\). Based on the calibration plot, what is the concentration of \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) in the unknown sample?

A student prepares five standard solutions of \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) and measures the absorbance of each at a wavelength of \(510\text{ nm}\) using a cuvette with a path length of \(1.0\text{ cm}\). The resulting calibration plot is shown below. The student then measures an unknown \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) sample under the same conditions and records an absorbance of \(0.30\). Based on the calibration plot, what is the concentration of \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) in the unknown sample?

![A line graph with bare axes showing Absorbance on the vertical y-axis ranging from 0.00 to 0.60 with tick marks every 0.10, and Concentration of Co(NO3)2 (M) on the horizontal x-axis ranging from 0.000 to 0.120 with tick marks every 0.020. A single solid straight line starts at origin (0.000, 0.00) and passes through five solid black circular data points at (0.020, 0.10), (0.040, 0.20), (0.060, 0.30), (0.080, 0.40), and (0.100, 0.50). Horizontal and vertical dashed gridlines extend from the axes to each data point. No other lines, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787143174-0K05Nf.jpg)

- **A.** \(0.015\text{ M}\)
- **B.** \(0.030\text{ M}\)
- **C.** \(0.060\text{ M}\)
- **D.** \(0.15\text{ M}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119262/*