( ( A ( redox reaction ) ) ( ( is ( ( any reaction ) ( ( in which ) ( electrons ( are ( ( ( removed ( from ( ( ( one molecule ) or ) atom ) ) ) and ) ( transferred ( to ( another ( ( molecule or ) atom ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN redox) (NN reaction)) (VP (VBZ is) (NP (NP (DT any) (NN reaction)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NNS electrons)) (VP (VBP are) (VP (VP (VBN removed) (PP (IN from) (NP (NP (CD one) (NN molecule)) (CC or) (NP (NN atom))))) (CC and) (VP (VBN transferred) (PP (TO to) (NP (DT another) (NN molecule) (CC or) (NN atom)))))))))) (. .)))
A redox reaction is any reaction in which electrons are removed from one molecule or atom and transferred to another molecule or atom.
(ROOT (S (ADVP (RB Replace)) (NP (NP (DT another)) (PP (IN in) (NP (DT a) (NN molecule)))) (VP (VBZ happens) (PP (TO to) (NP (NNS atoms))) (PP (IN during) (NP (DT a) (NN substitution) (NN reaction)))) (. .)))
Replace another in a molecule happens to atoms during a substitution reaction.