SCIENTIFIC PICTURE RESEARCH / SCIENCE PHOTO LIBRARY SCIENTIFIC PICTURE RESEARCH / SCIENCE PHOTO LIBRARY
Close-up of a scientist's gloved hands using a digital pH meter to measure the pH of a chemical solution. The tip of the probe is immersed in to the liquid and measurements are taken to determine its pH. A pH reading below 7 is acidic, one above 7 is alkaline, while a pH of 7 is neutral.
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