( Ethylene ( ( is ( ( a ( small hydrocarbon ) ) ( consisting ( of ( ( ( four ( hydrogen atoms ) ) and ) ( two ( carbon atoms ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Ethylene)) (VP (VBZ is) (NP (NP (DT a) (JJ small) (NN hydrocarbon)) (VP (VBG consisting) (PP (IN of) (NP (NP (CD four) (NN hydrogen) (NNS atoms)) (CC and) (NP (CD two) (NN carbon) (NNS atoms))))))) (. .)))
Ethylene is a small hydrocarbon consisting of four hydrogen atoms and two carbon atoms.
(ROOT (S (NP (NNS Hydrocarbons)) (VP (VBP are) (VP (VBN made) (PP (IN of) (NP (NP (CD one) (NN carbon)) (CC and) (NP (CD four) (NN hydrogen) (NNS atoms)))))) (. .)))
Hydrocarbons are made of one carbon and four hydrogen atoms.