Which of the following molecules can form hydrogen bonds with water?

• A. C2H6
• B. CO2
• C. NH3
• D. CH4

Answer: (C)

Verified step by step guidance

1. Understand what hydrogen bonding is: it is a special type of dipole-dipole interaction that occurs when a hydrogen atom is covalently bonded to a highly electronegative atom (usually N, O, or F) and is attracted to a lone pair of electrons on another electronegative atom.
2. Examine each molecule to see if it contains hydrogen atoms bonded to N, O, or F, which are necessary for hydrogen bonding with water.
3. For C2H6 (ethane), note that it contains only carbon and hydrogen atoms, with no N, O, or F atoms, so it cannot form hydrogen bonds with water.
4. For CO2 (carbon dioxide), although it contains oxygen atoms, the molecule is linear and nonpolar, and there are no hydrogen atoms bonded to oxygen, so it cannot form hydrogen bonds with water.
5. For NH3 (ammonia), it contains nitrogen bonded to hydrogen atoms, and nitrogen has a lone pair of electrons, so it can both donate and accept hydrogen bonds with water molecules, making it capable of hydrogen bonding.