Final answer:
A covalently bonded molecule is most likely to be an insulator because it lacks free-moving charges that can conduct electricity, unlike ions in a solution, metals, or compounds with metallic bonding.
Step-by-step explanation:
The question asks which of the given options is most likely to be an insulator. An insulator is a material that does not conduct electricity. The options include: A. Ions dissolved in water, B. A covalently bonded molecule, C. A compound containing metallic bonds, D. A piece of solid metal.
Options A, C, and D are typically associated with electrical conductivity. Ions in solution can conduct electricity, compounds with metallic bonding generally have free-moving electrons that allow electricity to flow, and solid metals are well-known conductors. In contrast, covalently bonded molecules (Option B), such as sugar or water, have no free-moving charges in their solid or pure liquid state and typically do not conduct electricity, making them insulators.