Which of the following compounds is generally considered insoluble in water?

The concept of solubility refers to the ability of a substance to dissolve in a solvent, typically water. When considering compounds that are generally insoluble in water, both carbonates and hydroxides fall under this category, making the choice of both A and C correct.

Carbonates, in general, do not dissolve well in water, with the notable exception of those involving alkali metals (like sodium or potassium carbonate) and ammonium carbonate. Most carbonates, such as calcium carbonate and magnesium carbonate, tend to remain largely undissolved in aqueous solutions.

Hydroxides also show a pattern of limited solubility in water. While some hydroxides, particularly those of alkali metals (like sodium hydroxide and potassium hydroxide), are soluble, many transition metal hydroxides and some alkaline earth metal hydroxides (like iron(III) hydroxide or magnesium hydroxide) are considered insoluble or only slightly soluble in water.

Thus, since both carbonate and hydroxide compounds are known for their general insolubility in water, the response indicating both A and C correctly identifies the compounds typically viewed as insoluble.