Which of the following factors does NOT affect the solubility of a solute in a solvent?

The correct choice highlights that the size of the solute particles does not significantly influence solubility in the same way that the other factors do. Solubility is primarily determined by how solute and solvent interact, which is influenced by temperature, the nature of the solutions involved (such as polar versus nonpolar), and pressure (especially for gases).

While smaller solute particles may dissolve more quickly due to a greater surface area exposed to the solvent, the actual solubility—the maximum amount of solute that can be dissolved—remains largely unchanged by particle size alone. In contrast, temperature typically affects the kinetic energy of molecules, impacting solubility; certain solutes dissolve better at higher temperatures, while gases may become less soluble. The nature of the solution dictates compatibility between solute and solvent, while pressure impacts solubility for gaseous solutes in particular.