any of the major appearances or aspects in which a thing of varying modes or conditions manifests itself to the eye or mind. 2. a stage in a process of change or development: Each phase of life brings its own joys. 3. a side, aspect, or point of view: This is only one phase of the question.
The pH of a neutral solution is 7. At this pH, the solution has equal concentrations of both the H+ and OH- ions, which is 10^-7 mole/litre. The presence of both the hydrogen and hydroxyl ions in equimolar concentrations makes the solution neutral.
The acidity or alkalinity of soil is measured by its pH. Neutral soil has a pH of about 6.5, while anything higher is alkaline and anything lower is acidic. Green beans grow best in neutral or near-neutral soil, though they can tolerate a pH anywhere between 5.5 and 7.5.