( Carbon-14 ( ( is ( ( ( an isotope ) ( of carbon ) ) ( which ( is radioactive ) ) ) ) . ) )
(ROOT (S (NP (NNP Carbon-14)) (VP (VBZ is) (NP (NP (DT an) (NN isotope)) (PP (IN of) (NP (NN carbon))) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (JJ radioactive))))))) (. .)))
Carbon-14 is an isotope of carbon which is radioactive.
(ROOT (S (NP (NP (NNP Carbon) (CD 14) (NN isotope)) (PP (IN of) (NP (NN carbon)))) (VP (VBZ is) (ADVP (RB typically)) (VP (VBN used) (PP (TO to) (NP (NN date) (JJ ancient) (NNS items))))) (. .)))