Question

Elevation in boiling point of an aqueous solution of urea is `0.52 ( k_(b) "for water"=0.52K"molality"^(-1))`. The mole fraction of urea in this solution is :
A. `0.982`
B. `0.018`
C. `0.0567`
D. `0.943`

Answer 1

Correct Answer - B
`0.52 = 0.52 xx m`
`m = 1` i.e., solution is 1m
Thus, the solution contains 1 mol of urea in `1000g (55.5mol)` of water
`:. x = (1)/(1+55.5) + (1)/(56.5) = 0.0177`