In sodium sulfate (NaSO4), the sodium (Na) forms an ionic bond with the sulfate ion (SO4). The oxygen atoms in the sulfate ion are covalently bonded to the sulfur atom.
The sodium-oxygen bond is ionic because sodium is a metal and loses an electron to form a positively charged ion (Na+), while oxygen is a non-metal that typically gains electrons. This transfer of electrons creates an ionic bond.
The sulfur-oxygen bonds within the sulfate ion are covalent, as sulfur and oxygen are both non-metals, and they share electrons to form these bonds.
Therefore, the correct response would be:
The sodium-oxygen bond, but not the sulfur-oxygen bond.