With which of the following compounds will NH_3 experience only ion-dipole intermolecular forces?

• A. CO_2
• B. NaCl (aq)
• C. CH_4
• D. H_2O

Answer: (B)

Verified step by step guidance

1. Identify the nature of NH_3 (ammonia): NH_3 is a polar molecule with a lone pair on nitrogen, capable of hydrogen bonding and dipole interactions.
2. Understand ion-dipole forces: Ion-dipole forces occur between an ion (charged species) and a polar molecule with a dipole moment.
3. Analyze each compound: CO_2 is nonpolar, so it interacts mainly via London dispersion forces; CH_4 is also nonpolar with only dispersion forces; H_2O is polar and can hydrogen bond with NH_3, so it involves hydrogen bonding and dipole-dipole forces, not just ion-dipole.
4. Consider NaCl (aq): In aqueous solution, NaCl dissociates into Na^+ and Cl^- ions, which can interact with the dipole of NH_3 through ion-dipole forces exclusively.
5. Conclude that NH_3 experiences only ion-dipole forces with NaCl (aq) because the interaction is between ions and the polar NH_3 molecules, without hydrogen bonding or other intermolecular forces dominating.