The correct option is **C. Pressure applied to the solution**. ### Detailed Explanation: To understand why pressure has the least effect on the solubility of a solid solute in a liquid solvent, we need to analyze how each of the given factors influences solubility. #### A. Temperature of the solvent - **Effect on Solubility**: Temperature is a significant factor affecting the solubility of solid solutes. Generally, as the temperature of the solvent increases, the solubility of most solid solutes also increases. This is because higher temperatures provide more kinetic energy to the molecules, allowing them to break apart and dissolve more readily. - **Example**: For instance, sugar dissolves more readily in hot water than in cold water. #### B. Nature of the solute - **Effect on Solubility**: The chemical nature of the solute plays a crucial role in its solubility. Different solutes have different solubility characteristics based on their molecular structure, polarity, and interactions with the solvent. For example, ionic compounds tend to dissolve well in polar solvents like water, while non-polar solutes dissolve better in non-polar solvents. - **Example**: Sodium chloride (NaCl) is highly soluble in water due to its ionic nature, while oil (a non-polar substance) does not dissolve in water. #### C. Pressure applied to the solution - **Effect on Solubility**: Pressure has a minimal effect on the solubility of solid solutes in liquid solvents. This is because solids are not significantly compressible, and their solubility is primarily determined by the interactions between solute and solvent molecules rather than the pressure applied. Pressure does have a more pronounced effect on the solubility of gases in liquids, where increased pressure can lead to greater solubility. - **Example**: The solubility of oxygen in water increases under high pressure, but this principle does not apply to solid solutes. #### D. Agitation of the solution - **Effect on Solubility**: Agitation (stirring or shaking) can enhance the rate at which a solid solute dissolves in a solvent. By increasing the movement of the solvent molecules, agitation helps to disperse the solute particles more quickly, leading to faster dissolution. However, it does not change the overall solubility limit of the solute in the solvent. - **Example**: Stirring sugar into water will help it dissolve faster, but it won't increase the maximum amount of sugar that can dissolve. ### Summary of Why Other Options Are Weaker: - **A (Temperature)**: Strongly affects solubility; higher temperatures generally increase solubility for solids. - **B (Nature of the solute)**: Critical factor; different solutes have different solubility characteristics based on their chemical properties. - **D (Agitation)**: Influences the rate of dissolution but not the solubility limit itself. ### Revision Summary: - **Temperature**: Higher temperatures usually increase the solubility of solid solutes. - **Nature of Solute**: Different solutes have varying solubility based on their chemical properties. - **Pressure**: Has minimal effect on solid solute solubility; more relevant for gases. - **Agitation**: Increases the rate of dissolution but does not affect the solubility limit. Understanding these factors is crucial for predicting how different substances will behave in solution, which is a fundamental concept in chemistry.