The vapour pressure of water at room temperature is 23.8 mm Hg. The vapour pressure of an aqueous solution of sucrose with mole fraction 0.1 is equal to

Options

A. 23.9 mm Hg
B. 24.2 Hg
C. 21.42 mm Hg
D. 21.44 mm Hg.

Answer

C

Explanation

`(P_(1)^(@)-P)/P_(1)^(@)= x_(2)`
or `p = p_(1)^(@) (1 - x_(2)) = 23.8 (1 - 0.1) = 21.42` mm
or directly , V.P. of solvent in the solution = mole of fraction of the solvent in the solution xx v.p. of pure solvent.