( ( ( ( ( Mass Number ) ( -LRB- ( A -RRB- ) ) ) - ) ( this ( is ( ( the number ) ( of ( ( ( protons and ) neutrons ) ( in ( the nucleus ) ) ) ) ) ) ) ) . )
(ROOT (NP (NP (NNP Mass) (NNP Number)) (PRN (-LRB- -LRB-) (NP (NNP A)) (-RRB- -RRB-)) (: -) (NP (NP (DT this)) (SBAR (S (VP (VBZ is) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS protons) (CC and) (NNS neutrons)) (PP (IN in) (NP (DT the) (NN nucleus)))))))))) (. .)))
Mass Number (A)- this is the number of protons and neutrons in the 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))))) (. .)))