Business / Agriculture / Ph: An expression of the intensity of the basic or acidic condition of a liquid or of soil: the logarithmic scale ranges from 0 to 14, where 0 is the most acid, 7 is neutral, and above 7 is alkaline. Natural waters usually have a ph between 6.5 and 8.5. Plants have differing tolerances for acidity and alkalinity.
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Science / Chemistry / Photon: A discrete packet of energy associated with electromagnetic radiation. Each photon carries energy E proportional to the frequency nu of the radiation: E = hnu, where h is Planck's constant. MORE