calculate the vapour pressure at 295 k of 0.1M solution of urea . The density of the solution may be taken as 1/gcm^​3 . The vapour pressure of pure water at 295k is 20 mm .

Let the volume of solution be 1000 ml. No of moles of urea = 0.1 mol
​So the mass of solution will be 1000 g.
Mass of urea = 0.1 mol * 60 g/mol
​                      = 6 g

Mass of water = 994 g
Moles of water = 994/180 = 55.22

Mole fraction of urea = 0.1/55.32 = 0.0018
Mole fraction of water = 0.9982

Vapour pressure of solution of urea = mole fraction of water * vapour pressure of pure water
                                                        = 0.9982*20 mm
                                                       = 19.964 mm