Which intermolecular force is primarily responsible for the formation of beads of water on a waxed car hood?

• A. Hydrogen bonding between water molecules
• B. Dipole-dipole interactions between water and wax
• C. London dispersion forces between water molecules
• D. Ionic bonding between water and wax

Answer: (A)

Verified step by step guidance

1. Identify the substances involved: water and wax. Water is a polar molecule capable of hydrogen bonding, while wax is nonpolar and hydrophobic.
2. Recall the types of intermolecular forces: hydrogen bonding, dipole-dipole interactions, London dispersion forces, and ionic bonding.
3. Consider the interaction between water molecules themselves: water molecules form strong hydrogen bonds due to the presence of highly polar O-H bonds and lone pairs on oxygen.
4. Consider the interaction between water and wax: since wax is nonpolar, it cannot engage in hydrogen bonding or strong dipole-dipole interactions with water; only weak London dispersion forces are possible.
5. Conclude that the beads of water form because water molecules stick to each other via hydrogen bonding rather than spreading out on the wax surface, which is due to the hydrophobic nature of wax and the strong hydrogen bonding between water molecules.