( ( If ( atoms ( ( can not ) ( be ( destroyed then ) ) ) ) ) ( ( ( the mass ) ( of reactants ) ) ( ( must ( equal ( ( the mass ) ( of ( ( the products ) ( in ( a ( chemical reaction ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (SBAR (IN If) (S (NP (NNS atoms)) (VP (MD can) (RB not) (VP (VB be) (VP (VBN destroyed) (ADVP (RB then))))))) (NP (NP (DT the) (NN mass)) (PP (IN of) (NP (NNS reactants)))) (VP (MD must) (VP (VB equal) (NP (NP (DT the) (NN mass)) (PP (IN of) (NP (NP (DT the) (NNS products)) (PP (IN in) (NP (DT a) (NN chemical) (NN reaction)))))))) (. .)))
If atoms cannot be destroyed then the mass of reactants must equal the mass of the products in a chemical reaction.
(ROOT (S (NP (NNS Atoms)) (VP (VBP make) (NP (NNS products)) (PP (IN by) (S (VP (VBG rearranging) (NP (PRP$ their) (NN chemical) (NNS bonds)) (PP (IN in) (NP (DT a) (NN reactant))))))) (. .)))