the vapour pressure is least for (a)pure water (b)0.1Maqueous urea (c)0.2Maqueous urea (d)0.3Maqueous urea
Urea has low vapour pressure compared to the vapour pressure of water. As the concentration of urea decreases the vapour pressure increases. 0.3M aqueous urea has the high urea concentration and hence has least vapour pressure.