Why is the vapous pressure of an aqueous solution of gulucose lower than that of water ?

Explanation

In pure liquid the entire surface of liquid is occupied by the molecules of wate. When a non-volatiles solute, e.g., glucose is dissolved in water, the fration of surface covered by the solvent molecules gets reduced because some positions are occupied by glucose molecules.
So. number of solvent molecules escaping from the surface is reduced. That is why vapour pressure of aqueous solution of glu cose is reduced.