( ( ( The ( specific gravity ) ) ( of ( a ( Sodium ( Chloride crystal ) ) ) ) ) ( ( is 2.16 ) . ) )
(ROOT (S (NP (NP (DT The) (JJ specific) (NN gravity)) (PP (IN of) (NP (DT a) (NNP Sodium) (NNP Chloride) (NN crystal)))) (VP (VBZ is) (NP (CD 2.16))) (. .)))
The specific gravity of a Sodium Chloride crystal is 2.16.
(ROOT (S (NP (NP (NNS Compounds)) (PP (IN like) (NP (NN sodium) (NN chloride) (NN form) (NNS structures)))) (VP (VBD called) (NP (NNS crystals))) (. .)))