Colligative properties of solution depend upon the number of particles present in solution. Experimental values colligative properties for electrolytes are always higher than these obtained theoretically because electrolyte dissociates to furnish more ions in solution. The ration of experimental values to theoretical values is called as van't Hoff factor `(i)`.
The correct order of freezing point for the following, each are `1` molal solutions in water and take `alpha = 1`:
(i) Urea , (ii) `NaCl`
(iii) `Na_(3)PO_(4)` , (iv) `Na_(2)SO_(4)`

Options

A. `iv lt ii lt iii lt i`
B. `iii lt iv lt ii lt i`
C. `I lt ii lt iv lt iii`
D. `iii lt iv lt I lt ii`

Answer

B

Explanation

`Delta T_(f) prop i`
So if `Delta T_(f)` is greater, `T_(f)` will be lower.