* Hydrogen bonds are indeed weak compared to covalent bonds. This is because they involve electrostatic interactions rather than sharing of electrons.

* Hydrogen bonds are specifically between molecules containing hydrogen bonded to a highly electronegative atom. These are usually oxygen, nitrogen, or fluorine.

* The molecules involved don't have to be polar. While hydrogen bonds often occur between polar molecules, they can also form between a polar molecule and a nonpolar molecule. The key is the presence of a hydrogen atom bonded to a highly electronegative atom in one of the molecules.

In summary:

* Hydrogen bonds are weak attractions.

* They involve hydrogen atoms bonded to highly electronegative atoms.

* They can occur between polar and nonpolar molecules.

It's important to note that although weak individually, hydrogen bonds can be collectively strong, playing a vital role in many biological processes.