( He ( ( ( ( started ( studying ( kinetic ( gas theory ) ) ) ) and ) ( ( moved on ) ( to ( ( ( elementary ( radiation theory ) ) and ) ( ( the ( molecular theory ) ) ( of matter ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VP (VBD started) (S (VP (VBG studying) (NP (JJ kinetic) (NN gas) (NN theory))))) (CC and) (VP (VBD moved) (PRT (RP on)) (PP (TO to) (NP (NP (JJ elementary) (NN radiation) (NN theory)) (CC and) (NP (NP (DT the) (JJ molecular) (NN theory)) (PP (IN of) (NP (NN matter)))))))) (. .)))
He started studying kinetic gas theory and moved on to elementary radiation theory and the molecular theory of matter.
(ROOT (S (NP (NP (DT The) (NN behavior)) (PP (IN of) (NP (JJ ideal) (NNS gases)))) (VP (VBZ is) (VP (VBN explained) (PP (IN by) (NP (JJ kinetic) (JJ molecular) (NN theory))))) (. .)))
The behavior of ideal gases is explained by kinetic molecular theory.