Final answer:
Hydrogen bonds between H₂O molecules are relatively strong due to the polar nature of the H-O bonds and the large electronegativity difference between hydrogen and oxygen. These hydrogen bonds contribute to water's unique properties such as high boiling and melting points, solvent ability, high heat capacity, and expansion upon freezing.
Step-by-step explanation:
Hydrogen bonds are relatively strong between H₂O molecules because of the highly polar nature of the H-O bonds and the large difference in electronegativity between hydrogen and oxygen. The large partial positive charge on the hydrogen atom is attracted to the large partial negative charge on the oxygen atom of a nearby water molecule, resulting in a dipole-dipole interaction.
These hydrogen bonds are indicated with a dotted line and are relatively weak compared to covalent bonds. However, in water, there are many hydrogen bonds, which collectively form strong cumulative interactions. These hydrogen bonds are responsible for water's high melting and boiling points, its ability to act as a solvent, its high heat capacity, and its expansion when freezing.