Here's why:
* pH scale: The pH scale measures the acidity or alkalinity of a solution.
* Neutral: A neutral solution has an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-).
* Water: Pure water is considered neutral. At 25 degrees Celsius, the concentration of H+ and OH- in water is 1 x 10^-7 moles per liter.
* pH Calculation: The pH is calculated using the formula: pH = -log[H+]. Since the concentration of H+ in pure water is 1 x 10^-7, the pH is -log(1 x 10^-7) = 7.
Therefore, a pH of 7 indicates a neutral solution.
