( ( ( ( Mass Number ) ( ( The sum ) ( of ( ( the number ) ( of ( ( neutrons and ) protons ) ) ) ) ) ) ( in ( a nucleus ) ) ) . )
(ROOT (NP (NP (NNP Mass) (NNP Number)) (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NNS neutrons) (CC and) (NNS protons)))))) (PP (IN in) (NP (DT a) (NN nucleus))) (. .)))
Mass Number The sum of the number of neutrons and protons in a nucleus .
(ROOT (S (NP (NP (DT The) (NN mass)) (PP (IN of) (NP (NNS atoms)))) (VP (VBZ is) (VP (VBN based) (PP (IN on) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NNS protons) (CC and) (NNS neutrons))))) (PP (IN in) (NP (NN nucleus))))) (. .)))