( ( ( ( ( Pulling up ) ( on ( the plunger ) ) ) ( ( decreased ( the ( air pressure ) ) ) ( inside ( ( the flask ) ( ( causing ( the ( water molecules ) ) ) ( to ( condense ( onto ( the smoke ) ) ) ) ) ) ) ) ) ( particles ( -LRB- ( ( condensation particles ) -RRB- ) ) ) ) . )
(ROOT (SINV (VP (VBG Pulling) (PRT (RP up)) (PP (IN on) (NP (DT the) (NN plunger)))) (VP (VBD decreased) (NP (DT the) (NN air) (NN pressure)) (PP (IN inside) (NP (NP (DT the) (NN flask)) (VP (VBG causing) (NP (DT the) (NN water) (NNS molecules)) (S (VP (TO to) (VP (VB condense) (PP (IN onto) (NP (DT the) (NN smoke)))))))))) (NP (NP (NNS particles)) (PRN (-LRB- -LRB-) (NP (NN condensation) (NNS particles)) (-RRB- -RRB-))) (. .)))
Pulling up on the plunger decreased the air pressure inside the flask causing the water molecules to condense onto the smoke particles (condensation particles).
(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))))) (. .)))