What is the primary factor that affects colligative properties?

Colligative properties are defined by their dependence on the number of solute particles present in a solution rather than the identity of those particles. This characteristic is key to understanding how these properties, such as boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering, are influenced by solute concentration.

When solute particles are added to a solvent, they disrupt the solvent's ability to evaporate, freeze, or boil effectively, which varies with the number of solute particles rather than their specific chemical nature. For instance, whether the solute is salt or sugar, the effects on the colligative properties will depend solely on how many particles are in solution, as these particles interact with the solvent molecules.

The other options focus on factors that do not govern colligative properties. The type of solute does not matter as long as the total number of particles is the same; temperature affects the solvent properties but not the colligative property itself; and while molar mass may influence how many moles of solute are present, it is ultimately the number of particles produced in solution that is the primary factor determining colligative properties.