Final answer:
Among the compounds NaCl, FeCO3, FeS, and AlPO4, only NaCl is soluble in water. FeCO3, FeS, and AlPO4 are not typically soluble due to the presence of carbonate, sulfide, and phosphate ions, respectively.
Step-by-step explanation:
To determine which of the compounds NaCl, FeCO3, FeS, and AlPO4 are soluble in water, we can refer to general solubility rules. Inorganic compounds like NaCl are typically soluble in water, so NaCl is expected to be soluble. However, there are exceptions, like CaCO3 (calcium carbonate), which is not soluble in water.
According to solubility rules, compounds containing the carbonate ion, like FeCO3 (iron(II) carbonate), and phosphate ion, such as AlPO4 (aluminum phosphate), are usually insoluble in water. Similarly, sulfides like FeS (iron(II) sulfide) are also not typically soluble in water. Thus, among the options given, only NaCl is soluble in water.