( It ( ( ( ( is ( a ( colourless gas ) ) ) , ) ( having ( ( a density ) ( of 0.92 ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (NP (DT a) (JJ colourless) (NN gas)) (, ,) (S (VP (VBG having) (NP (NP (DT a) (NN density)) (PP (IN of) (NP (NNP 0.92))))))) (. .)))
It is a colourless gas, having a density of 0.92.
(ROOT (S (NP (NNS Gases)) (VP (VBP have) (NP (DT the) (JJS lowest) (NN density))) (. .)))