JEE Main 2025 Jan 29 Shift 1, Chemistry Q3: Colligative Properties

For a weak electrolyte, ionisation is governed by Ostwald's dilution law: the degree of dissociation $\alpha$ rises steeply as concentration falls, and ${\Lambda }_m=\alpha {\Lambda }_m^{\infty }$.

Consequently a plot of ${\Lambda }_m$ vs $\sqrt{C}$ shows a sharp fall as concentration increases (i.e. as $\sqrt{C}$ grows), and ${\Lambda }_m$ approaches ${\Lambda }_m^{\infty }$ only asymptotically at very high dilution. This is qualitatively different from a strong electrolyte's near-linear Debye-Huckel-Onsager behaviour.