Final answer:
A solution with equal numbers of hydrogen ions and hydroxide ions is neutral. This neutrality is characterized by a pH of 7, and occurs when the concentrations of H3O+ and OH- are each 1 × 10-7 M.
Step-by-step explanation:
A solution containing equal numbers of hydrogen ions (H+) and hydroxide ions (OH-) is considered neutral. This is represented by a concentration of hydronium ions ([H3O+]) equal to 1 × 10-7 M. If the concentration of hydronium ions in a solution is greater than 1 × 10-7 M, the solution is acidic; if it is less, the solution is basic or alkaline .When water ionizes, it naturally produces equal amounts of H+ and OH-, resulting in a pH of 7, which is the very definition of a neutral solution. The presence of equal concentrations of these ions results in neither acidic nor basic qualities prevailing, hence the neutrality of the solution.