( ( When ( ( a solute ) ( is ( dissolved ( in ( a solvent ) ) ) ) ) ) ( , ( ( ( ( ( ( ( the number ) ( of ( ( solvent molecules ) ( near ( the surface ) ) ) ) ) decreases ) , ) and ) ( ( ( the ( vapor pressure ) ) ( of ( the solvent ) ) ) decreases ) ) . ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT a) (NN solute)) (VP (VBZ is) (VP (VBN dissolved) (PP (IN in) (NP (DT a) (JJ solvent))))))) (, ,) (S (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (JJ solvent) (NNS molecules)) (PP (IN near) (NP (DT the) (NN surface)))))) (VP (VBZ decreases))) (, ,) (CC and) (S (NP (NP (DT the) (NN vapor) (NN pressure)) (PP (IN of) (NP (DT the) (JJ solvent)))) (VP (VBZ decreases))) (. .)))
When a solute is dissolved in a solvent, the number of solvent molecules near the surface decreases, and the vapor pressure of the solvent decreases.
(ROOT (S (S (VP (VBG Reducing) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS molecules)) (PP (IN in) (NP (DT a) (JJ rigid) (NN container)))))))) (VP (VBZ causes) (NP (NN pressure)) (S (VP (TO to) (VP (VB decrease))))) (. .)))