( ( Each ( water molecule ) ) ( ( contains ( ( ( ( one atom ) ( of oxygen ) ) and ) ( ( two atoms ) ( of hydrogen ) ) ) ) . ) )
(ROOT (S (NP (DT Each) (NN water) (NN molecule)) (VP (VBZ contains) (NP (NP (NP (CD one) (NN atom)) (PP (IN of) (NP (NN oxygen)))) (CC and) (NP (NP (CD two) (NNS atoms)) (PP (IN of) (NP (NN hydrogen)))))) (. .)))
Each water molecule contains one atom of oxygen and two atoms of hydrogen.
(ROOT (S (NP (NP (CD 2) (NN hydrogen)) (, ,) (NP (CD 1) (NN oxygen) (NNS atoms))) (VP (VBP combine) (S (VP (TO to) (VP (VB make) (PRT (RP up)) (NP (NP (DT a) (NN molecule)) (PP (IN of) (NP (NN water)))))))) (. .)))
2 hydrogen, 1 oxygen atoms combine to make up a molecule of water.