Which of the following compounds has the highest boiling point?

• A. H_2O
• B. NH_3
• C. CH_4
• D. CO_2

Answer: (A)

Verified step by step guidance

1. Identify the types of intermolecular forces present in each compound: H_2O, NH_3, CH_4, and CO_2. These forces largely determine boiling points.
2. Recall that hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine.
3. Analyze each compound: H_2O has hydrogen bonding due to O-H bonds; NH_3 has hydrogen bonding but weaker than water because nitrogen is less electronegative than oxygen; CH_4 is nonpolar and only has weak London dispersion forces; CO_2 is linear and nonpolar, so it also only has London dispersion forces.
4. Understand that stronger intermolecular forces require more energy (higher temperature) to break, leading to higher boiling points.
5. Conclude that since H_2O exhibits the strongest hydrogen bonding among the options, it will have the highest boiling point.