I2 is an example of which covalent molecule

Yes, it has only a single covalent bond.

Explanation:

It has only a pair of electrons between the iodine atoms in order to gain a stable arrangement of 8 electrons in its outer shell. It is sharing them, so it's a covalent bond as a single iodine atom cannot be stable on its own. It's a halogen and is a single covalently-bonded diatomic molecule.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).