The depression of freezing point of a dilute solution is directly proportional to which quantity?

1. For dilute solutions, $\Delta T_f \propto m$, where m is molality. 2. Introducing Kf gives $\Delta T_f = K_f m$. 3. Like boiling point elevation, it is tied to molality, not molarity or mole fraction of solvent. _Source: NCERT Class 12 Chemistry Ch 1 "Solutions", p.17_