---
title: "A student prepares a \\(0.60 \\text{ M}\\) aqueous solution of magnesium chloride, \\(\\text{MgCl}_2\\text{(aq)}\\). The particulate model shown represents a \\(10.0 \\text{ mL}\\) sample of this solution. The student then dilutes the entire \\(10.0 \\text{ mL}\\) sample by adding distilled water until the total volume reaches \\(30.0 \\text{ mL}\\). Which of the following correctly identifies the number of \\(\\text{Mg}^{2+}\\) and \\(\\text{Cl}^-\\) ions that should be drawn in an identical box to represent a \\(10.0 \\text{ mL}\\) sample of the diluted solution, and provides the correct justification?"
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url: "https://nerd-notes.com/ubq/123729/"
date_modified: "2026-09-28T12:02:13+00:00"
---

# A student prepares a \(0.60 \text{ M}\) aqueous solution of magnesium chloride, \(\text{MgCl}_2\text{(aq)}\). The particulate model shown represents a \(10.0 \text{ mL}\) sample of this solution. The student then dilutes the entire \(10.0 \text{ mL}\) sample by adding distilled water until the total volume reaches \(30.0 \text{ mL}\). Which of the following correctly identifies the number of \(\text{Mg}^{2+}\) and \(\text{Cl}^-\) ions that should be drawn in an identical box to represent a \(10.0 \text{ mL}\) sample of the diluted solution, and provides the correct justification?

A student prepares a \(0.60 \text{ M}\) aqueous solution of magnesium chloride, \(\text{MgCl}_2\text{(aq)}\). The particulate model shown represents a \(10.0 \text{ mL}\) sample of this solution. The student then dilutes the entire \(10.0 \text{ mL}\) sample by adding distilled water until the total volume reaches \(30.0 \text{ mL}\). Which of the following correctly identifies the number of \(\text{Mg}^{2+}\) and \(\text{Cl}^-\) ions that should be drawn in an identical box to represent a \(10.0 \text{ mL}\) sample of the diluted solution, and provides the correct justification?

![A single square diagram container representing a fixed sample volume of an aqueous solution. At the top, a legend defines two symbols: a filled black circle represents \(\text{Mg}^{2+}\) and an open white circle with a solid black outline represents \(\text{Cl}^-\). Inside the square boundary, exactly 3 filled black circles and exactly 6 open white circles are dispersed throughout the area. One filled circle is positioned in the upper-left quadrant, one in the center, and one in the lower-right quadrant. The six open circles are distributed uniformly in the surrounding spaces between the filled circles, with none touching each other or the container walls. Solvent water molecules are omitted for clarity. No other particles, lines, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790596932-5kFzZG.jpg)

- **A.** \(3\text{ Mg}^{2+}\) ions and \(6\text{ Cl}^-\text{ ions}\), because the total moles of solute particles remain constant when water is added during the dilution process.
- **B.** \(3\text{ Mg}^{2+}\) ions and \(2\text{ Cl}^-\text{ ions}\), because only the concentration of the anion decreases when the total solution volume increases by a factor of \(3\).
- **C.** \(1\text{ Mg}^{2+}\) ion and \(6\text{ Cl}^-\text{ ions}\), because the cation concentration decreases by a factor of \(3\) while the number of anions must remain equal to the initial representation.
- **D.** \(1\text{ Mg}^{2+}\) ion and \(2\text{ Cl}^-\text{ ions}\), because the concentration of each ion decreases by a factor of \(3\) while maintaining the \(1:2\) stoichiometric ratio.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123729/*