Question

6g of non-volatile, non-electrolyte `x` dissolved in 100g of water freezes `-0.93^(@)C`. The molar mass of `x` in `"g mol"^(-1)` is :
`(K_(f) "of" H_(2)O=1.86 "K kg mol"^(-1))`
A. 60
B. 140
C. 180
D. 120

Answer 1

Correct Answer - D
`DeltaT=k_(f)xx(w_(B)xx1000)/(m_(B)xxw_(A))`
`0.93=1.86xx(6xx1000)/(m_(B)xx100)`
`m_(B)=(1.86xx6xx1000)/(0.93xx100)=120`]