What is the mass of urea required to prepare 0.25 molal 2.5kg aqueous solution of urea (NH_(2)CONH_(2))?

The Van't Hoff factor i for a 0.2 molal aqueous solution of urea is

The amount of urea required to prepare 1L of its 0.1 M aqueous solution is _______ g.

At 298 K , the vapour pressure of water is 23.75 mm Hg . Calculate the vapour pressure at the same temperature over 5% aqueous solution of urea. [CO(NH_(2))_(2)] .