The freezing point (in °C) of a solution containing 0.1 g of `K_(3)[Fe(CN)_(6)]` (Mol.wt 329) in 100 g of water (`K_(f) = 1.86 kg "mol"^(-1)` is:

Options

A. `-2.3 xx 10^(-2)`
B. `5.7 xx 10^(-2)`
C. `-5.7 xx 10^(-3)`
D. `-1.2 xx 10^(-2)`

Answer

A

Explanation

`(DeltaT_(f))_("solution") = (DeltaT_(f))_("solvent")`
`-(DeltaT_(f))_("solvent with solute")`
`(DeltaT_(f))_("Solute") = ("molality" xx K_(f)) xx i`
`= 0.1/(329 xx 100) xx 1000 xx 4 xx 1.86`
`= 0.022^(@)` C
So, `(DeltaT_(f))_("Solution") = 0 - 0.2232`
`~= 2.3 xx 10^(-2)`