( ( ( The amount ) ( of ( product ( that ( is ( produced ( during ( a reaction ) ) ) ) ) ) ) ) ( ( is ( the ( actual yield ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN product)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN produced) (PP (IN during) (NP (DT a) (NN reaction)))))))))) (VP (VBZ is) (NP (DT the) (JJ actual) (NN yield))) (. .)))
The amount of product that is produced during a reaction is the actual yield.
(ROOT (S (NP (NP (NNS Substances)) (VP (VBN produced) (PP (IN by) (NP (DT a) (NN reaction))))) (VP (VBP are) (VP (VBN known) (PP (IN as) (NP (NNS products))))) (. .)))