Based on solubility rules, which of the following compounds is soluble in water?

• A. BaSO_4
• B. AgCl
• C. NaNO_3
• D. PbI_2

Answer: (C)

Verified step by step guidance

1. Recall the general solubility rules for ionic compounds in water, which help predict whether a compound will dissolve or form a precipitate.
2. Identify that most nitrates (NO_3^-) are soluble in water without exceptions, so compounds containing the nitrate ion are typically soluble.
3. Recognize that BaSO_4 (barium sulfate) is generally insoluble or sparingly soluble in water due to the sulfate ion's limited solubility with barium.
4. Note that AgCl (silver chloride) is insoluble in water, as most silver halides (Cl^-, Br^-, I^-) are poorly soluble.
5. Understand that PbI_2 (lead iodide) is also insoluble or sparingly soluble in water, as lead halides tend to have low solubility except for PbCl_2 which is moderately soluble.