Fluidity as a shared property of liquids and gases

Steps:

• Recall that liquids and gases are states of matter with weak intermolecular forces allowing movement.
• Identify common properties: both lack fixed shape and can flow.
• Evaluate choices: A applies only to gases; B to solids/liquids; C to both; D to solids.
• Confirm C matches the definition of fluids.

Why C is correct:

• Liquids and gases are fluids, defined by their ability to flow due to particles that slide past each other (kinetic molecular theory).

Why the others are wrong:

• A: Liquids have fixed volume and do not always fill containers; only gases expand to fill space.
• B: Gases are highly compressible; liquids are slightly compressible but not like gases.
• D: Particles in liquids and gases move freely, unlike fixed positions in solids.

Final answer: C