The vapour pressure of a solution of a non-volatile electrolyte `B` in a solvent `A` is `95%` of the vapour pressure of the solvent at the same temperature. If the molecular weight of the solvent is `0.3` times, the molecular weight of solute, the weight ratio of the solvent and solute are:

Options

A. 0.15
B. 5.7
C. 0.2
D. 4

Answer

B

Explanation

`"P"_("solution")=0.95"P"_("solvent")^(0)`
` "m"_("solvent")=0.3" m"_("solute")`
`("P"_("solvent")^(0)-"P"_("solution"))/("P"_("solution"))=("W"_("solute")xx"m"_("solvent"))/("m"_("solute")xx"W"_("solvent"))`
`("P"^(0)-0.95"P"^(0))/(0.95"P"^(0))="W"_("solute")/"W"_("solvent")xx0.3`
`"W"_("solute")/"W"_("solvent")=0.3xx19=5.7`