Assuming very dilute aqueous solution of urea, calculate the vapour pressure of solution (in mm of Hg) of 0.1 moles of urea in 180 grams of water at `25^(@)C` is (The vapour pressure of water at `25^(@)C` is 24 mm Hg)

Options

A. 2. 376 mm Hg
B. 20.76 mm Hg
C. 23.76 mm Hg
D. 24.76 mm Hg

Answer

C

Explanation

From Raoult.s law for very dilute soluton.
`( p ^(@) - p _(s))/( p ^(@)) = (w)/( m) xx ( M )/(W)`
`( 24- p _(s))/( 24) = 0.1 xx (18)/(180)`
`24 = p _(s) = 0. 24`
`therefore p _(s) = 24 - 0. 24 = 23. 76 mm Hg`