Final answer:
The compound expected to be ionic among the given options is K2O, as it is composed of a metal (potassium) and a nonmetal (oxygen), typical of ionic compounds.
Step-by-step explanation:
To determine which of the given substances would be expected to be ionic, we should look at the types of atoms involved and their positions in the periodic table. An ionic compound generally forms between a metal and a nonmetal. Here are the options:
- Co is cobalt, a metal, but as a single element, it does not form a compound and thus is not ionic.
- H2O (water) consists of hydrogen and oxygen, both nonmetals, and is therefore covalent.
- SO2 (sulfur dioxide) is composed of sulfur and oxygen, both nonmetals, making it a covalent compound.
- K2O (potassium oxide) has potassium (a metal) and oxygen (a nonmetal), typical of an ionic compound.
- O2 is oxygen as a diatomic molecule, which is not an ionic compound but a covalent one.
Therefore, the compound we would expect to be ionic among the given options is K2O.