The vapour pressure of a dilute aqueous solution of glucose is 740 mm of mercury at 373 K. The mole fraction of the solute is:

Options

A. `(1)/(20)`
B. `(1)/(38)`
C. `(1)/(76)`
D. `(1)/(760)`

Answer

B

Explanation

`(p^(@)-p_(s))/(p^(@)) = x_(B)` (mole fraction of the solute)
At `373 K (100^(@)C) V.P.` of pure water,
`p^(@) = 760`mm of Hg
`:.` mole fraction of solute `= (760 - 740)/(760) = (1)/(38)`