What is the primary factor leading to the differences in colligative properties among different solutions?

Colligative properties depend primarily on the number of solute particles in a solution rather than their identity. This means that the effects on properties like boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure arise from the quantity of dissolved species—ions or molecules—rather than their specific chemical nature.

For example, when ionic compounds dissolve in a solvent, they often dissociate into multiple ions, increasing the total number of solute particles significantly compared to a non-electrolyte that does not dissociate. Therefore, two solutions of different concentrations but the same type of solute can exhibit different colligative properties solely due to the varying total number of particles.

Options related to the type of solute, temperature, and density do not affect the core principle of colligative properties as directly as the total number of dissolved particles does. Thus, the primary factor influencing the differences in colligative properties is indeed the total number of solute particles present in the solution.