Sodium chloride (NaCl) forms an ionic bond, characterized by the electrostatic attraction between positively and negatively charged ions. This strong electrostatic interaction results in a high melting and boiling point, indicating strong bonding in the solid state.

Covalent network crystals are characterized by a strong and rigid three-dimensional network of covalent bonds, resulting in higher melting points compared to molecular crystals, which are held together by weaker intermolecular forces.

Copper is a metal that primarily exhibits ionic bonds, unlike the other options, which are all made up of covalent bonds. Ice is a form of water, diamond is pure carbon, and graphite is also pure carbon, all of which contain covalent bonds.

Nitrogen and phosphorus tend to form covalent bonds due to their similar electronegativities, resulting in compounds such as ammonia (NH3) and phosphine (PH3). This is in contrast to ionic compounds, which typically form between metals and nonmetals with large electronegativity differences.

Ethylene diammine is a bidentate ligand as it has two donor atoms that can bind to a central metal atom, forming two coordinate covalent bonds. This allows it to occupy two coordination sites.

Ionic bonds occur when one atom loses an electron to become a positively charged ion (cation), and another atom gains an electron to become a negatively charged ion (anion). Sharing of electrons is not a characteristic of ionic bonds, as it is more typical of covalent bonds.

LiOH is the least ionic due to the small size of Li+, resulting in higher covalent character. It decomposes into Li2O when heated, unlike other alkali metal hydroxides which are more ionic and stable.

Covalent molecular substances consist of discrete molecules held together by weak intermolecular forces, such as London dispersion forces or dipole-dipole interactions. Because these forces are significantly weaker than the strong covalent bonds within the molecules or the ionic bonds in crystal lattices, relatively little thermal energy is required to overcome them, resulting in low melting and boiling points.

Van der Waals forces are weak, short-range electrostatic attractive forces between uncharged molecules, including London dispersion forces, dipole-dipole interactions, and Debye forces. They are significantly weaker than chemical bonds like covalent, ionic, or coordinate bonds, which involve the sharing or transfer of electrons to create stable chemical structures.

Water molecules are highly polar due to the electronegativity difference between oxygen and hydrogen. The partial positive charge on the hydrogen atom of one water molecule is attracted to the partial negative charge on the oxygen atom of a neighboring water molecule. This specific type of strong dipole-dipole interaction is known as a hydrogen bond.