Which of the following `0.10 M` aqueous solution will have the lowest freezing point?

Options

A. `C_(12)H_(22)O_(11)`
B. `C_(5)H_(10)O_(8)`
C. `Al_(2)(SO_(4))_`
D. `KI`

Answer

3

Explanation

We have
`DeltaT_(f)= I K_(f)m`
Thus, for a given solvent and given concentration, `DeltaT_(f)` is directly porportional to `i` (van't hoff factor) i.e. maximum `T_(f)` (and hence lowest freezing point) will correspond to maximum value of `i`.
`C_(12)H_(22)O_(11) overset(H_(2)O) (rarr)" No ionization "(i=1)`
`C_(5)H_(10)O_(8) overset(H_(2)O) (rarr)" No ionization " (i=1)`
`Al_(2)(SO_(4))_(3)overset(H_(2)O)(rarr) 2Al^(3+) + 3SO_(4)^(2-) (i=5)`
`Kl overset(H_(2)O)(rarr) K^(+)+I^(-) (i=2)`
Hence, `0.10 M (~~0.10 m)` aqueous solution will have the lowest feezing point.