What amount of urea dissolved in 1 kg water at constant temperature ,so that vapour pressure of the solution reduced by 2% ? ( MV of urea= 60 gm `//` mole )

Options

A. 68 gm
B. 60gm
C. 50 gm
D. 75 gm

Answer

A

Explanation

`Delta P= ( 2P^(0))/( 100)`
`:. (Delta P)/( P^(0)) =(1)/(50) =X ` ( mole fraction of urea )
`= ( m )/( 55.55 + m ) `
`:. M= 1.134 ` ( malality of urea )
`:. `Mass of urea `( W_(2)) = 1.134 xx 60 = 68 gm`