( ( In ( nuclear reactions ) ) ( , ( ( the half-life ) ( ( is ( ( the amount ) ( of ( time ( ( required ( for ( one-half ( of ( ( the ( radioactive nuclei ) ) ( in ( a sample ) ) ) ) ) ) ) ( to decay ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (JJ nuclear) (NNS reactions))) (, ,) (NP (DT the) (NN half-life)) (VP (VBZ is) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN time)) (VP (VBN required) (PP (IN for) (NP (NP (NN one-half)) (PP (IN of) (NP (NP (DT the) (JJ radioactive) (NN nuclei)) (PP (IN in) (NP (DT a) (NN sample))))))) (PP (TO to) (NP (NN decay)))))))) (. .)))
In nuclear reactions, the half-life is the amount of time required for one-half of the radioactive nuclei in a sample to decay.
(ROOT (S (NP (DT The) (NN term) (NN half-life)) (VP (VBZ decribes) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN time)) (VP (VBN required) (PP (IN for) (NP (NP (NN half)) (PP (IN of) (NP (DT the) (JJ original) (NN material))))) (PP (TO to) (NP (NP (NN decay)) (PP (IN in) (NP (DT an) (NN isotope)))))))))) (. .)))