Correct Answer - A
Depression in freezing point `prop` number of particles. In colligative properties ions behave like particles. `Al_(2)(SO_(4))_(3)` provides five ions on ionisation as
`Al_(2)(SO_(4))_(3)rarr 2 Al^(3+)+3SO_(4)^(2-)`
`KI hArr K^(+)+I^(-)`
while KI provides two ions and `C_(5)H_(10)O_(5)` and `C_(12)H_(22)O_(11)` are not ionised, so they have single particle. Hence, lowest freezing point is possible for `Al_(2)(SO_(4))_(3)`.
