Question

`0.15`g of a subatance dissolved in `15`g of solvent boiled at a temperature higher at `0.216^(@)`than that of the pure solvent. Calculate the molecular weight of the substance. Molal elecation constant for the solvent is `2.16^(@)C`
A. 216
B. 100
C. 178
D. None of these

Answer 1

Correct Answer - B
Here it is given that
`"w"=0.15"g, " Delta"T"_("b")=0.216^(@)"C"`
`"W"=15"g""K"_("b")=2.16^(@)"C ""m"?`
Substituting values in the expression,
`"m"=(1000xx"K"_("b")xx"w")/(Delta"T"_("b")xx"")" m"=(1000xx2.16xx0.15)/(0.216xx15)=100`