( ( ( ( ( ( ( The ( gas phase ) ) ( of water ) ) ( is ( known ( as ( water vapor ) ) ) ) ) , ) and ) ( it ( is invisible ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (NN gas) (NN phase)) (PP (IN of) (NP (NN water)))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (NN water) (NN vapor)))))) (, ,) (CC and) (S (NP (PRP it)) (VP (VBZ is) (ADJP (JJ invisible)))) (. .)))
The gas phase of water is known as water vapor, and it is invisible.
(ROOT (S (NP (NNP Water) (NN vapor)) (VP (VBZ exists) (PP (IN in) (NP (NP (DT the) (NN atmosphere)) (PP (IN as) (NP (DT an) (JJ invisible) (NN gas))))))))
Water vapor exists in the atmosphere as an invisible gas