Which of the following is responsible for dipole-dipole intermolecular forces between molecules?

• A. The attraction between the positive end of one polar molecule and the negative end of another polar molecule
• B. The sharing of electrons between atoms to form covalent bonds
• C. The attraction between ions and polar molecules
• D. The instantaneous fluctuations in electron density that create temporary dipoles

Answer: (A)

Verified step by step guidance

1. Understand that dipole-dipole intermolecular forces occur between polar molecules, which have permanent dipoles due to uneven distribution of electron density.
2. Recognize that these forces arise from the electrostatic attraction between the positive end of one polar molecule and the negative end of another polar molecule.
3. Eliminate options that describe other types of interactions: covalent bonds involve sharing electrons within a molecule, not between molecules; ion-dipole forces involve ions and polar molecules, not just polar molecules alone; and instantaneous dipoles relate to London dispersion forces, which are temporary and occur in all molecules.
4. Conclude that the correct description of dipole-dipole forces is the attraction between the positive end of one polar molecule and the negative end of another polar molecule.
5. Summarize that dipole-dipole forces are specific to polar molecules interacting through their permanent dipoles, distinguishing them from other intermolecular forces.