Which of the following substances is generally insoluble in water?

• A. NaNO_3
• B. K_2SO_4
• C. NH_4Br
• D. AgCl

Answer: (D)

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, while others are insoluble or sparingly soluble.
2. Recall common solubility rules for ionic compounds in water: For example, most nitrates (NO_3^-), alkali metal salts (like Na^+, K^+), and ammonium (NH_4^+) salts are soluble in water.
3. Analyze each given substance using solubility rules: NaNO_3 contains nitrate ion, which is generally soluble; K_2SO_4 contains potassium and sulfate ions, both generally soluble; NH_4Br contains ammonium and bromide ions, both generally soluble.
4. Recognize that AgCl (silver chloride) is a classic example of an insoluble salt in water, as silver halides (except AgF) are typically poorly soluble.
5. Conclude that among the options, AgCl is generally insoluble in water, while the others are soluble according to standard solubility rules.