Assertion (A): The boiling point of water is abnormally high compared to hydrides of other group 16 elements like hydrogen sulfide and hydrogen selenide. Reason (R): Water molecules form extensive intermolecular hydrogen bonding networks due to the high electronegativity and small size of the oxygen atom.

💡 Solution & Explanation

Oxygen is highly electronegative and small, allowing water molecules to form strong intermolecular hydrogen bonds that require substantial thermal energy to break during phase transition, resulting in an elevated boiling point. Other group 16 hydrides are gases at room temperature because they rely on weaker dipole-dipole and London dispersion forces. Hydrogen bonding also accounts for the unusual maximum density of liquid water at four degrees Celsius.