**Correct Option: C. Pressure of the gas above the solution** ### Detailed Explanation: To understand why option C is the correct answer, we need to analyze how each of the listed factors affects the solubility of a solid solute in a liquid solvent. #### A. Temperature of the solvent - **Effect on Solubility**: The temperature of the solvent is a significant factor affecting the solubility of solid solutes. Generally, as the temperature increases, the solubility of most solid solutes in liquids also increases. This is because higher temperatures provide more kinetic energy to the molecules, allowing them to break apart and interact with the solvent more effectively. - **Example**: For instance, sugar dissolves more readily in hot water than in cold water. #### B. Stirring of the solution - **Effect on Solubility**: Stirring or agitating the solution can enhance the rate at which a solid solute dissolves in a solvent. While stirring does not change the solubility limit of the solute, it helps distribute the solute particles throughout the solvent more quickly, allowing for faster dissolution. - **Example**: When you stir a cup of coffee with sugar, the sugar dissolves faster compared to leaving it undisturbed. #### C. Pressure of the gas above the solution - **Effect on Solubility**: The pressure of the gas above the solution primarily affects the solubility of gases in liquids, not solids. For solid solutes, changes in pressure have a negligible effect on their solubility. This is because solids are not compressible, and their solubility is more influenced by temperature and the nature of the solute and solvent. - **Conclusion**: Therefore, option C is the correct answer as it does not significantly affect the solubility of a solid solute in a liquid solvent. #### D. Nature of the solute and solvent - **Effect on Solubility**: The chemical nature of both the solute and the solvent is crucial in determining solubility. Polar solutes tend to dissolve well in polar solvents (like salt in water), while non-polar solutes dissolve better in non-polar solvents (like oil in hexane). This principle is often summarized by the phrase "like dissolves like." - **Example**: Sugar (a polar solute) dissolves well in water (a polar solvent), while oil (a non-polar solute) does not dissolve in water. ### Summary of Why Other Options Are Incorrect: - **Option A**: Temperature significantly affects solubility; higher temperatures usually increase solubility for solids. - **Option B**: Stirring increases the rate of dissolution but does not change the solubility limit; it is still a significant factor. - **Option D**: The nature of the solute and solvent is fundamental to solubility; it determines whether a solute will dissolve in a given solvent. ### Common Pitfalls: - Students may confuse the effects of pressure on gases with solids. Remember that pressure mainly affects gas solubility. - It’s important to distinguish between the rate of dissolution (which can be affected by stirring) and the actual solubility limit (which is affected by temperature and the nature of the substances involved). ### Revision Summary: - **Temperature**: Higher temperatures generally increase the solubility of solid solutes. - **Stirring**: Enhances the rate of dissolution but does not affect the solubility limit. - **Pressure**: Has a negligible effect on the solubility of solid solutes; mainly affects gases. - **Nature of Solute and Solvent**: Critical for determining solubility; "like dissolves like."