Final answer:
LiCl is the most soluble compound in water, while naphthalene is the least soluble.
Step-by-step explanation:
The solubility of a compound in water is determined by its interactions with water molecules. Polar and ionic compounds, which have positive and negative charges, are most soluble in water because water molecules are polar and can form hydrogen bonds with the charged species. Nonpolar compounds, which have no charged regions, are generally insoluble in water.
LiCl is an ionic compound with strong interactions with water molecules, making it highly soluble. Benzoic acid has both polar and nonpolar regions, but its polar carboxylic acid group allows it to form hydrogen bonds with water, making it moderately soluble. Naphthalene, a nonpolar compound, has weak interactions with water and is the least soluble.
Therefore, the compound most soluble in water among LiCl, benzoic acid, and naphthalene is LiCl, and the least soluble is naphthalene.