Final answer:
The defining property of matter in the liquid state is that it has a definite volume but not a definite shape, meaning liquids take the shape of their container while the particles within are free to move over one another.
Step-by-step explanation:
The property of matter in the liquid state is that it has a definite volume but not a definite shape.
Liquids are capable of flowing and take the shape of their containers because the particles within are able to move freely over each other while still remaining in contact.
A key characteristic of most liquids is that they cannot be compressed to any significant extent and have a surface that is distinct, except when in contact with a gas.
Liquids exhibit surface tension, like mercury, which is unique among metals due to its liquid form at room temperature.
Surface tension is the property that causes a liquid to stick to itself, and mercury demonstrates a relatively high level of it.
Additionally, the particles in liquids are close enough to each other to allow for strong intermolecular forces that maintain a consistent volume under ordinary conditions.