Final answer:
Option B is correct because a given mass of liquid has a fixed volume at room temperature due to the close packing of particles and strong intermolecular forces, unlike gases which are more compressible.
Step-by-step explanation:
The correct statement about liquids and gases is option B: A given mass of liquid has a fixed volume at room temperature. This is because the particles in a liquid are closely packed together and have less space between them compared to gas particles. Liquids are less compressible because of the strong intermolecular forces between the particles. Gases, on the other hand, have much larger amounts of empty space between particles, making them more compressible. Moreover, the particles in a liquid do -not have fixed positions, contrary to what is suggested in option D.