Which of the following substances is generally insoluble in water?

• A. AgCl
• B. NaNO3
• C. K2SO4
• D. NH4Br

Answer: (A)

Verified step by step guidance

1. Understand the concept of solubility: Solubility refers to the ability of a substance (solute) to dissolve in a solvent, such as water. Ionic compounds that dissociate into ions in water are generally soluble, but there are exceptions based on the ions involved.
2. Recall the solubility rules for common ionic compounds in water: For example, most nitrates (NO\_3\^-), alkali metal salts (like K\^+), and ammonium salts (NH\_4\^+) are soluble in water.
3. Analyze each given compound based on these rules: NaNO\_3 contains the nitrate ion, which is generally soluble; K\_2SO\_4 contains potassium (an alkali metal) and sulfate, which is generally soluble; NH\_4Br contains ammonium and bromide ions, both of which form soluble salts.
4. Identify the exception: AgCl contains silver (Ag\^+) and chloride (Cl\^-). According to solubility rules, most silver salts are insoluble except for a few exceptions, making AgCl generally insoluble in water.
5. Conclude that among the given options, AgCl is the substance that is generally insoluble in water due to the low solubility of silver chloride.