Which phrase best describes intermolecular forces?

• A. Forces within a single molecule
• B. Forces that bind nuclei together
• C. Forces that occur between different molecules
• D. Forces that move electrons between atoms

Answer: (C)

Intermolecular forces are the attractions that occur between separate molecules. They help explain why substances have specific melting and boiling points, why some compounds mix and others don’t, and how liquids form and maintain their structures. The best description is that these are forces that occur between different molecules, such as hydrogen bonds between water molecules, dipole-dipole interactions, and London dispersion forces. These interactions are generally weaker than the bonds that hold atoms together within a single molecule, which are intramolecular bonds like covalent bonds. Nuclear forces act inside atomic nuclei, not between molecules, and “moving electrons between atoms” describes electron transfer or bond formation rather than the general category of forces acting between molecules.