Which type of intermolecular force is generally the strongest for substances with similar molar mass?

• A. Dipole-dipole interactions
• B. Hydrogen bonding
• C. Ion-dipole interactions
• D. London dispersion forces

Answer: (B)

Verified step by step guidance

1. Identify the types of intermolecular forces listed: dipole-dipole interactions, hydrogen bonding, ion-dipole interactions, and London dispersion forces.
2. Understand that ion-dipole interactions occur between ions and polar molecules, so they are not generally applicable to neutral substances with similar molar mass.
3. Recognize that London dispersion forces are present in all molecules but are usually the weakest type of intermolecular force, especially for molecules of similar size and molar mass.
4. Compare dipole-dipole interactions and hydrogen bonding: both occur between polar molecules, but hydrogen bonding is a special, stronger type of dipole-dipole interaction that happens when hydrogen is bonded to highly electronegative atoms like N, O, or F.
5. Conclude that for substances with similar molar mass, hydrogen bonding is generally the strongest intermolecular force because it involves a strong attraction due to highly polar bonds and the ability to form hydrogen bonds.