( Acidity ( ( is ( measured ( by ( the ( pH scale ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Acidity)) (VP (VBZ is) (VP (VBN measured) (PP (IN by) (NP (DT the) (NN pH) (NN scale))))) (. .)))
Acidity is measured by the pH scale.
(ROOT (S (NP (NP (DT The) (NN acidity)) (PP (IN of) (NP (DT a) (NN solution)))) (VP (VBZ is) (ADVP (RB typically)) (VP (VBN assessed) (ADVP (RB experimentally)) (PP (IN by) (NP (NP (NN measurement)) (PP (IN of) (NP (PRP$ its) (NN ph.)))))))))