Freezing point depression is directly proportional to the no. of dissolved particles, ΔTf=ikfm. But freezing point is inversely proportional to no. of dissolved particles.
Compounds
Number of Ions or van’t Hoff Factor (i)
Al2(SO4)3→2Al3++3SO42−
5
BaCl2→Ba2++2Cl−
3
AlCl3→Al3++3Cl−
4
NH4Cl→NH4+Cl−
2
Therefore, it can be concluded that NH4Cl has a highest freezing point as i = 2.