Question

The mole fraction of a solute in a solutions is `0.1`. At `298K` molarity of this solution is the same as its molality. Density of this solution at 298 K is `2.0 g cm^(-3)`. The ratio of the molecular weights of the solute and solvent, `(MW_("solute"))/(MW_("solvent"))` is

Answer 1

Correct Answer - 9
When `M = m`
`(w_(B)xx1000)/(m_(B)xxV)=(w_(B)xx1000)/(m_(B)xxw_(A))`
i.e., `V=w_(A)`
Volume of solution = Mass of solvent
`("Mass of solution")/("Density")=` Mass of solvent
`(w_(A)+w_(B))/(2)=w_(B)`
`w_(A)=w_(B)`
`x_(A)xxm_(A)=x_(B)xxm_(B)`
`0.9xxm_(A)=0.1xxm_(B)`
`(m_(B))/(m_(A))=9`
`(MW_("solute"))/(MW_("solvent"))=9`]