The vapour pressure of a solution (made by dissolving a solute in a solvent) is __________ that of the pure solvent.

ANS:A - less than

The vapor pressure of a solution (formed by dissolving a solute in a solvent) is generally less than that of the pure solvent. This phenomenon is known as vapor pressure depression. When a solute is dissolved in a solvent, the solvent molecules at the surface are replaced by solute molecules. These solute molecules reduce the number of solvent molecules at the surface, decreasing the number of solvent molecules that can escape into the vapor phase. As a result, the vapor pressure of the solution is lower than that of the pure solvent. So, the correct option is: less than