according to solubility rules, which compound should not dissolve in water?

The compound that should not dissolve in water (i.e., is insoluble) according to standard solubility rules is typically something like barium sulfate, BaSO₄ , or silver chloride, AgCl. These are classic “insoluble in water” examples used in most solubility rules charts.

Quick Scoop: Core Idea

According to common solubility rules used in high school and intro college chemistry:

• Most alkali metal (Group 1) salts and ammonium (NH₄⁺) salts are soluble.

• Most nitrates (NO₃⁻) and acetates (CH₃COO⁻) are soluble.

• Many chlorides, bromides, and iodides are soluble, except those of Ag⁺, Pb²⁺, and Hg₂²⁺ , which are insoluble (e.g., AgCl).

• Most sulfates (SO₄²⁻) are soluble, but BaSO₄, PbSO₄, and CaSO₄ are commonly listed as insoluble or only very slightly soluble (BaSO₄ is the go‑to “insoluble” example).

• Most carbonates (CO₃²⁻), phosphates (PO₄³⁻), and hydroxides (OH⁻) are insoluble unless paired with Group 1 cations or ammonium.

So in a multiple‑choice question that asks:

“According to solubility rules, which compound should not dissolve in water?”

the best answer is usually something like BaSO₄(s) or AgCl(s) , because standard rules classify them as insoluble in water.

Information gathered from public forums or data available on the internet and portrayed here.