Which solution will exhibit the GREATEST freezing point depression for #1*mol*L^-1# aqueous solutions of: #"(i) propanol; (ii) potassium bromide; (iii) calcium bromide?"#
And a colligative property depends on the NUMBER of solute particles, not their identity. Solute-solvent interactions tend to (i) INCREASE the boiling point of solutions by an amount proportional to the number (i.e. concentration) of solute particles, and (ii) depress the melting point of solutions RELATIVE to pure solvent, again by reason of solute-solvent interactions.
In each solution, the concentration is
All the solutions are
So in terms of melting point, the calcium bromide solution should be LOWEST, and next is the potassium bromide solution, and the next is the propanol solution. The elevation of boiling point follows the reverse order.