This phenomenon is called endosmosis, i.e. movement of water inside the raisin and shown with the help of diagram as:

The process of osmosis is of immense biological as well as industrial importance. It is evident from the following examples:
(i) Movement of water from soil into plant roots and subsequently into upper portion of the plant is partly due to osmosis.
(ii) Preservation of meat against bacterial action by the addition of salt.
(iii) Preservation of fruits against bacterial action by adding sugar. Bacterium in canned fruit loses water through the process of osmosis and become inactive.
(iv) Reverse osmosis is used in desalination of water.

NaCl is a non-volatile solute. So, its addition to water lowers the vapour pressure of water. Hence, boiling point of water (solution) increases. Whereas methyl alcohol is more volatile than water. So, its addition to water increases the total vapour pressure of the solution. It results in decrease of boiling point of water.

In the solution, the surface has both solute and solvent molecules, so the fraction of the surface covered by solvent molecules gets reduced. Thus, the number of solvent molecules escaping from the surface is reduced, resulting in lowering the vapour pressure. So, the vapour pressure of the solution of glucose in water is lower than that of pure water.

This can be understood by saying "like dissolves like" . It means understood by saying "like dissolves likes" . It means that polar or ionic compound (like NaCl) dissolve in polar solvents (like water) and almost insoulable in non polar solvents (like benzene).

(b) If x_A is mol fraction of A in liquid phase, then x_A (450)+(1 - x_A)(700) = 600 or x_A = 0.4, x_B = 0.6.
Hence, \({ p }_{ A }=0.4\times 450=180\quad mm,{ p }_{ B }=0.6\times 700=420\quad mm,{ y }_{ A }=\frac { 180 }{ 600 } =0.3,{ y }_{ B }=\frac { 420 }{ 600 } =0.7\)