( Argon ( ( ( ( ( ( makes up ) just ) ( under ( ( 1 % ) ( of ( ( the ( Earth 's ) ) atmosphere ) ) ) ) ) , ) ( making ( it ( ( the ( third ( ( most abundant ) gas ) ) ) ( in ( ( the atmosphere ) ( after ( ( nitrogen and ) oxygen ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Argon)) (VP (VBZ makes) (PRT (RP up)) (ADVP (RB just)) (PP (IN under) (NP (NP (CD 1) (NN %)) (PP (IN of) (NP (NP (DT the) (NN Earth) (POS 's)) (NN atmosphere))))) (, ,) (S (VP (VBG making) (S (NP (PRP it)) (NP (NP (DT the) (JJ third) (ADJP (RBS most) (JJ abundant)) (NN gas)) (PP (IN in) (NP (NP (DT the) (NN atmosphere)) (PP (IN after) (NP (NN nitrogen) (CC and) (NN oxygen)))))))))) (. .)))
Argon makes up just under 1% of the Earth's atmosphere, making it the third most abundant gas in the atmosphere after nitrogen and oxygen.
(ROOT (S (NP (NN Nitrogen) (NN gas)) (VP (VBZ comprises) (NP (NP (QP (RB about) (NNS three-fourths))) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN atmosphere))))) (. .)))