Substances that are alkaline are basic, or the opposite of acidic — they have a high pH, while acids have a low pH. Lower pH ...

The pH scale measures how acidic or alkaline a substance is, measured on a scale from 0 to 14, in which 0 is the most acidic.

These water samples have other substances dissolved in them. They might show up as slightly acidic or slightly alkaline because of this. The pH scale measures how strongly acidic or alkaline a ...