Final answer:
Ethanol has the highest boiling point among methane, ethane, ethanol, and dimethyl ether due to its ability to form strong hydrogen bonds.
Step-by-step explanation:
Among methane, ethane, ethanol, and dimethyl ether, ethanol has the highest boiling point. This is because ethanol (CH3CH²OH) can participate in hydrogen bonding due to its hydroxyl (-OH) group. Hydrogen bonds are a type of strong dipole-dipole interaction that significantly increases the amount of energy required to separate the molecules, leading to a higher boiling point compared to other types of intermolecular forces like London dispersion forces or dipole-dipole interactions without hydrogen bonding. Methane (CHD) and ethane (C²H`) are nonpolar molecules with only London dispersion forces, which are the weakest type of intermolecular forces. Dimethyl ether (CH3OCH3), although it is polar and experiences dipole-dipole interactions, lacks the ability to form hydrogen bonds, resulting in a lower boiling point than ethanol.