Which of the following is an example of a molecular compound?

A molecular compound is formed when two or more nonmetals share electrons through covalent bonds. In the case of boron trifluoride (BF3), it is composed of boron and fluorine, both of which are nonmetals. The bonding occurs through the sharing of electrons, resulting in a distinct molecular structure.

The other choices represent ionic compounds rather than molecular compounds. Sodium chloride (NaCl), for example, is formed from the ionic bond between sodium and chlorine, which involves the transfer of electrons from sodium to chlorine. Similarly, calcium oxide (CaO) and potassium sulfate (K2SO4) consist of metal ions bonded to nonmetal ions, indicating the formation of ionic bonds. In contrast, boron trifluoride's structure showcases the characteristics of a molecular compound, highlighting its covalent nature.