Question

what is ph?
the concentration of hydrogen ions in a solution
the intensity with which a solution can burn you
the amount of water in a solution

Explanation:

pH is a measure of the hydrogen - ion concentration in a solution. It indicates whether a solution is acidic, basic, or neutral. A lower pH value means a higher hydrogen - ion concentration (more acidic), and a higher pH value means a lower hydrogen - ion concentration (more basic).

Answer:

the concentration of hydrogen ions in a solution