Emissions of sulfur dioxide by industry set off chemical changes in the atmosphere that result in "acid rain." the acidity of liquids is measured by ph on a scale of 0 to 14. distilled water has ph 7.0 , and lower ph values indicate acidity. normal rain is somewhat acidic, so acid rain is sometimes defined as rainfall with a ph below 5.0. a sample of 105 rainwater specimens had mean ph 5.43; standard deviation 0.54; and five‑number summary 4.33, 5.05 , 5.44 , 5.79 , 6.81. compare the mean and median and also the distances of the two quartiles from the median.