Sometimes when extraction a polar organic solute into
anorganic solvent, brine (a saturated solution of sodium chloride)
isused in place of water. what is the advantage of using
brinerather than water?

Increasing salt will increase the force of surface tension which simultaneously increases the density of the aqueous layer hence enhance the separation.

Explanation:

We know that emulsion is the process of dispersion of one layer into the other. Due to this dispersion, the separation between two-layer becomes delayed. Thus, it become necessary intensify the separation. The breaking of emulsion can be done by salt addition in the mixture, or by using NaCl which is called as brine. Increasing salt will increase the force of surface tension which simultaneously increases the density of the aqueous layer hence enhance the separation.