( Then ( , ( ( if ( ( carbon dioxide ) ( is ( formed ( of ( ( ( ( one atom ) ( of carbon ) ) and ) ( ( two atoms ) ( of oxygen ) ) ) ) ) ) ) ) ( , ( ( the proportion ) ( ( ( must naturally ) ( ( consist ( of ( ( 3 parts ) ( of carbon ) ) ) ) ( to ( 8 ( of oxygen ) ) ) ) ) . ) ) ) ) ) )
(ROOT (S (RB Then) (, ,) (SBAR (IN if) (S (NP (NN carbon) (NN dioxide)) (VP (VBZ is) (VP (VBN formed) (PP (IN of) (NP (NP (NP (CD one) (NN atom)) (PP (IN of) (NP (NN carbon)))) (CC and) (NP (NP (CD two) (NNS atoms)) (PP (IN of) (NP (NN oxygen)))))))))) (, ,) (NP (DT the) (NN proportion)) (VP (MD must) (ADVP (RB naturally)) (VP (VB consist) (PP (IN of) (NP (NP (CD 3) (NNS parts)) (PP (IN of) (NP (NN carbon))))) (PP (TO to) (NP (NP (CD 8)) (PP (IN of) (NP (NN oxygen))))))) (. .)))
Then, if carbon dioxide is formed of one atom of carbon and two atoms of oxygen, the proportion must naturally consist of 3 parts of carbon to 8 of oxygen.
(ROOT (S (NP (NNP Carbon) (NN dioxide) (NNS molecules)) (VP (VBP consist) (PP (IN of) (NP (NP (DT a) (JJ central) (NN carbon) (NN atom)) (VP (VBN bonded) (PP (TO to) (NP (CD two) (NN oxygen) (NNS atoms))))))) (. .)))