Answer: (A) acidity
Explanation: Acidity is a measure of how acidic a substance is. pH is a system used to measure the H+ ion concentration in a substance. Using the equation -log([H+]=pH, if given a pH value less than 7, a substance is acidic, and greater than 7 indicates basicity.
Common indicators are phenolphthalein and bromthymol blue which turn different colors depending on the acidity of the solution they're in. This color tells us nothing about the boiling point, density, or electrical conductivity.
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