In a 0.5 molal solution KCl, KCl is 50% dissociated. The freezing point of solution will be (`K_(f)` = 1.86 K kg `mol^(-1)`):

Options

A. 274. 674 K
B. 271.60 K
C. 273K
D. None of these

Answer

B

Explanation

`underset(1-alpha)(KCl) rArr underset(alpha)(K^(+)) + underset(alpha)(Cl^(-))`
Total number of particles at e.g.
`1 - alpha + alpha + alpha= 1 + alpha`
`=1+0.5`
`DeltaT_f = ikg m`
`DeltaT_f = (1 + 0.5) xx 1.86 xx0.5 =1.395`
`:. T_f = 273 - 1.395 = 271.60`