Why is the vapour pressure of a solvent lowered by the ạddition of a non- volatile solute?

Explanation

In a solution.containing non- yolatile solute, the surface of solution contains both volatile solvent molecules and non- volatile solute molecules. As the solute is non-volatile, the number of molecules that escapes from the liquid side to the vapour side decreasés. This results in less number
.x.
of molecules in the yapour state at a given.temperatute and results in the decreases in vapour pressure