Rank the following compounds in order of increasing boiling point: CH4, NH3, H2O, NaCl.

• A. NaCl < H2O < NH3 < CH4
• B. CH4 < NH3 < H2O < NaCl
• C. H2O < NH3 < CH4 < NaCl
• D. NH3 < CH4 < NaCl < H2O

Answer: (B)

Verified step by step guidance

1. Identify the types of intermolecular forces present in each compound: CH4 has London dispersion forces, NH3 has hydrogen bonding and dipole-dipole interactions, H2O has strong hydrogen bonding, and NaCl is an ionic compound with ionic bonds.
2. Recall that boiling point generally increases with the strength of intermolecular forces: ionic bonds > hydrogen bonds > dipole-dipole interactions > London dispersion forces.
3. Compare CH4, NH3, and H2O based on their hydrogen bonding capabilities: CH4 has only weak London forces, NH3 has moderate hydrogen bonding, and H2O has stronger hydrogen bonding due to two hydrogen atoms bonded to oxygen.
4. Recognize that NaCl, being an ionic compound, has the strongest intermolecular forces (ionic bonds), leading to the highest boiling point among the given compounds.
5. Rank the compounds in order of increasing boiling point based on the strength of their intermolecular forces: CH4 < NH3 < H2O < NaCl.