( ( ( Most ( carbon atoms ) ) ( in ( the world ) ) ) ( ( have ( ( ( six protons ) and ) ( ( six neutrons ) ( in ( their nucleus ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJS Most) (NN carbon) (NNS atoms)) (PP (IN in) (NP (DT the) (NN world)))) (VP (VBP have) (NP (NP (CD six) (NNS protons)) (CC and) (NP (NP (CD six) (NNS neutrons)) (PP (IN in) (NP (PRP$ their) (NN nucleus)))))) (. .)))
Most carbon atoms in the world have six protons and six neutrons in their nucleus.
(ROOT (S (NP (NP (DT A) (NN carbon) (NN atom)) (PP (IN with) (NP (NP (CD 6) (NNS protons)) (CC and) (NP (CD 8) (NNS neutrons))))) (VP (VBZ is) (ADVP (RBR more) (RB specifically)) (VP (VBN known) (PP (IN as) (NP (NN carbon) (CD 14))))) (. .)))
A carbon atom with 6 protons and 8 neutrons is more specifically known as carbon 14.