Final answer:
Pure liquid water is neutral because it has a pH of 7, which is the neutral point on the pH scale.
Step-by-step explanation:
Pure liquid water is described as neutral because the water's pH is 7. This value is the point of neutrality on the pH scale, where a pH lower than 7 indicates an acidic substance and a pH higher than 7 indicates a basic (or alkaline) substance. For example, milk of magnesia, with a pH of 10.5, is basic, while wine, with a pH of 3.0, is acidic. Pure water has a pH of 7, making it neither acidic nor basic.