When a solution contains an equal number of H+ and OH- ions, then the pH of the solution is:

A solution is neutral when the amount of hydrogen ions (H+) is equal to the amount of hydroxide ions (OH-). The pH scale goes from 0 to 14, and pH 7 is the neutral point, where H+ and OH- concentrations are equal. Pure water is a common example of a neutral solution, with a pH of 7 at 25°C. pH is calculated using the formula pH=-log[H+], and for neutral solutions, [H+] is 1×10^-7 mol/L, resulting in a pH of 7.