Which physical state of matter has a definite volume but not a definite shape?

The correct answer is liquid because liquids possess a characteristic that allows them to occupy a definite volume while taking the shape of their container. This means that regardless of the boundaries of the container, a liquid will always fill the space available to it, conforming to various shapes without losing its volume.

In contrast, solids have both a definite shape and a definite volume, maintaining their form regardless of the environment. Gases, on the other hand, do not have a definite volume or shape; they expand to fill the entire available space, adapting to the container they are in. Plasma, which is an ionized state of matter found in stars and neon signs, also lacks a definite shape and volume. Thus, only liquids uniquely fit the criteria of having a definite volume without a fixed shape.