The density of a solution prepared by dissolving 120g of urea ( mol .mass `=60` u ) in 1000g of water is 1.15 g/mL the molality of the solution is :

Options

A. 0.50 M
B. 1.78 M
C. 1.02 M
D. 2.05 M

Answer

B, D

Explanation

Mole of solute `= (120)/(60)`
wt. of solution `= 1000 + 120 = 1120`
Volume `=` weight/density `= 1120//1.15`
`M= ("mole of solute" xx 1000)/("volume of solution")`
`= (120)/(60) xx (1000xx1.15)/(1120) = 2.0536 mol. L^(-1) ~~ 2.05`