( ( The pH ) ( ( is ( ( a scale ) ( that ( measures ( ( ( ( ( ( the ( hydrogen ( ion concentration ) ) ) , ) or ) ( the acidity ) ) , ) ( of ( a solution ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN pH)) (VP (VBZ is) (NP (NP (DT a) (NN scale)) (SBAR (WHNP (WDT that)) (S (VP (VBZ measures) (NP (NP (NP (DT the) (NN hydrogen) (NN ion) (NN concentration)) (, ,) (CC or) (NP (DT the) (NN acidity)) (, ,)) (PP (IN of) (NP (DT a) (NN solution))))))))) (. .)))
The pH is a scale that measures the hydrogen ion concentration, or the acidity, of a solution.
(ROOT (S (NP (NP (DT The) (NN concentration)) (PP (IN of) (NP (NP (NN hydrogen) (NNS ions)) (PP (IN in) (NP (DT a) (NN solution)))))) (VP (VBZ is) (VP (VBN called) (ADVP (RB acidity)))) (. .)))