Which of the following bonds are broken when ethanol is boiled? I. Covalent bonds II. Ionic bonds III. Hydrogen bonds

The correct answer is III only - hydrogen bonds are broken when ethanol is boiled. Ethanol is a molecule that contains both polar and nonpolar regions due to the presence of the hydroxyl (-OH) group. The polar region of ethanol allows it to form hydrogen bonds with neighboring ethanol molecules. These hydrogen bonds are relatively weak and require less energy to break than covalent or ionic bonds. When ethanol is boiled, the increased thermal energy breaks the hydrogen bonds between the ethanol molecules, allowing the molecules to escape into the gas phase. The covalent bonds within the ethanol molecules and the ionic bonds between any ions present in the solution are not affected by boiling and remain intact.