Which of the following compounds dissolves readily in water?

Among the given compounds, only NH4Cl dissolves readily in water. This is because NH4Cl is an ionic compound, composed of ammonium (NH4+) and chloride (Cl-) ions. When NH4Cl is added to water, the water molecules surround the ions, separating them from each other and forming a solution. This process is called hydration or solvation. On the other hand, BaSO4, CuSO3, and AgCl are insoluble or only slightly soluble in water. BaSO4 and AgCl are both ionic compounds, but they have very low solubility in water. CuSO3 does not exist as a stable compound under normal conditions, and it is usually synthesized as a complex or in a solution of a different solvent. Therefore, the compound that dissolves readily in water among the given options is NH4Cl.