The freezing point (in `.^@C`) of solution containing 0.1 g of `K_(3)[Fe(CN)_(6)]` (molecular weight 329) in 100 g of water `(K_(f) = 1.86 K kg mol^(-1))` is

Options

A. `-2.3xx10^(-2)`
B. `-5.7xx10^(-2)`
C. `-5.7xx10^(-3)`
D. `-1.2xx10^(-2)`

Answer

a

Explanation

van't Hoff factor (i) `= 4{3K^(+) + Fe(CN)_(6))^(3-)}`
Molality `= (0.1xx1000)/(329xx100) = (1)/(329)`
`-DeltaT_(f) = iK_(f)m = 4xx1.86xx(1)/(329) = 2.3xx10^(-2)`
`rArr DeltaT_(f) = -2.3xx10^(-2)C`
(As freezing point of water is `0^(@)C`)