What do CaO(s) and H2O(l) yield when reacted together?

When calcium oxide (CaO) reacts with water (H2O), it undergoes a chemical reaction to form calcium hydroxide (Ca(OH)2). This reaction is an example of a hydration reaction, where a solid compound (CaO) reacts with liquid water to produce a new aqueous compound.

Calcium hydroxide is commonly known as slaked lime and is only slightly soluble in water. As a result, the product can be present in aqueous solution form, which is reflected in the answer choice indicating it as Ca(OH)2(aq). In this case, the 'aq' signifies that the calcium hydroxide forms a solution in water, even though some of it may also precipitate out of solution depending on the concentration.

The other options do not represent the correct products of this established chemical reaction. For instance, CaO2 is not produced from this reaction, and while Ca(OH)2(s) indicates a solid form of the compound, it does not specifically address the presence of water, which is critical in this reaction. CaH2O4 does not represent a compound formed in this reaction either. Thus, the formation of calcium hydroxide in solution is accurate when considering the interaction between CaO and H