<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> In chemistry, pH (/ piːˈ (h) eɪ tʃ /) (potential of hydrogen) is a numeric scale used to specify the acidity or basicity of an aqueous solution . It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions . More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion . Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic . Pure water is neutral, at pH 7 (25 ° C), being neither an acid nor a base . Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively . </P> <P> pH measurements are important in agronomy, medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment and water purification, as well as in many other applications . </P>

What level on the ph scale is a solution considered acidic