Question

in what way are liquids different from solids? liquid molecules are lighter than solid molecules. liquids are made of atoms; solids are made of molecules. liquids don’t have a fixed shape; solids do. liquids are always denser than solids.

Explanation:

• Option 1: Molecule weight isn't determined by state (liquid/solid); same substance has same - weight molecules in both states. So this is wrong.
• Option 2: Both liquids and solids can be made of atoms or molecules (e.g., liquid mercury is atoms, solid water is molecules). So this is wrong.
• Option 3: Solids have a fixed shape (their particles are closely packed in a fixed arrangement), while liquids take the shape of their container (particles are less tightly packed and can move more freely). This is correct.
• Option 4: Not always true (e.g., ice is less dense than liquid water). So this is wrong.

Answer:

C. Liquids don't have a fixed shape; solids do.