An example of a covalent bond is found in which molecule?

The correct answer is found in the molecule O2, which is a diatomic molecule consisting of two oxygen atoms. A covalent bond occurs when two atoms share one or more pairs of electrons. In the case of O2, each oxygen atom shares two electrons with the other, forming a double bond. This sharing of electrons is characteristic of covalent bonding, where atoms are held together by the mutual attraction of their nuclei for the shared electrons.

In contrast, H2O contains covalent bonds as well, with hydrogen and oxygen atoms sharing electrons, and CO2 also consists of covalent bonds between carbon and oxygen atoms. NaCl, on the other hand, is an example of an ionic bond, which occurs when an electron is transferred from one atom to another, resulting in the formation of charged ions that attract each other. Thus, while both O2 and the other two molecules, H2O and CO2, have covalent bonds, O2 specifically represents a simple molecular compound formed solely by covalent bonds.