Question

20 g of a non-volatile solute is added to 500 g of solvent. Freezing point of solvent `= 5.48^(@)C` and solution `= 4.47^(@)C. K_(f)=1.93^(@)//m`. Molecular mas of the solute is
A. `72.2`
B. `76.4`
C. `73.2`
D. `70.6`

Answer 1

Correct Answer - B
`Delta T_(f)=5.48-4.47=1.01`
`Delta T_(f)=K_(f)xx m`
`rArr 1.01=1.93xx(20)/(M)xx(1000)/(500)rArr M=76.4`.