Which of the following best describes dipole-dipole interactions?

• A. Attractive forces between polar molecules due to the alignment of their permanent dipoles.
• B. Attractive forces between nonpolar molecules caused by temporary dipoles.
• C. Repulsive forces between molecules with similar charges.
• D. Forces between ions and polar molecules.

Answer: (A)

Verified step by step guidance

1. Understand that dipole-dipole interactions occur between molecules that have permanent dipoles, meaning the molecules are polar with regions of partial positive and partial negative charge.
2. Recognize that these interactions are attractive forces that arise because the positive end of one polar molecule is attracted to the negative end of another polar molecule.
3. Differentiate dipole-dipole interactions from other types of intermolecular forces, such as London dispersion forces (which occur between nonpolar molecules due to temporary dipoles) and ion-dipole forces (which occur between ions and polar molecules).
4. Note that dipole-dipole interactions are not repulsive forces; rather, they are attractive forces that help hold polar molecules together in the liquid or solid state.
5. Conclude that the best description of dipole-dipole interactions is: 'Attractive forces between polar molecules due to the alignment of their permanent dipoles.'