( ( 2 . ) ( Heterogeneous Mixtures ) )
(ROOT (S (NP (CD 2) (. .)) (VP (VBZ Heterogeneous) (NP (NNS Mixtures)))))
2.  Heterogeneous Mixtures
(ROOT (S (NP (NNS Heterogeneous)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (DT a) (NN mixture)) (SBAR (WHNP (WDT that)) (S (VP (VBZ varies) (PP (IN in) (NP (PRP$ its) (NN composition)))))))))) (. .)))