( ( Molecular mass ) ( ( is ( ( the sum ) ( of ( ( the ( atomic masses ) ) ( of ( elements ( in ( a compound ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Molecular) (NN mass)) (VP (VBZ is) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (NP (DT the) (JJ atomic) (NNS masses)) (PP (IN of) (NP (NP (NNS elements)) (PP (IN in) (NP (DT a) (NN compound))))))))) (. .)))
Molecular mass is the sum of the atomic masses of elements in a compound.
(ROOT (S (NP (DT A) (JJ binary) (JJ molecular) (NN compound)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (CD two) (NNS elements))))) (. .)))