Solids with mixed bonding types

Steps:

• Recall bonding in each solid: iodine (I₂) has covalent intramolecular bonds and van der Waals intermolecular forces.
• Silicon dioxide (SiO₂) features a network of covalent bonds throughout.
• Sodium chloride (NaCl) consists entirely of ionic bonds in a lattice.
• Zinc chloride (ZnCl₂) also forms an ionic lattice with electrostatic attractions.
• Identify the solid with both covalent and dispersion forces as having multiple types.

Why A is correct:

• Iodine molecules are held by covalent bonds internally, but the solid lattice uses van der Waals forces, fitting the definition of a molecular solid with dual bonding.

Why the others are wrong:

• B: Silicon dioxide is a pure covalent network solid with only covalent bonds.
• C: Sodium chloride is an ionic solid with exclusively ionic bonding.
• D: Zinc chloride is ionic, dominated by electrostatic attractions between ions.

Final answer: A