The symbol of a sodium ion followed by the formula of a sulfate ion is:

Na₂SO₄

Here's why:

* Sodium ion (Na⁺): Sodium loses one electron to become a positively charged ion.

* Sulfate ion (SO₄²⁻): The sulfate ion is a polyatomic ion with a 2- charge.

To balance the charges, two sodium ions (2+) are needed to balance the charge of one sulfate ion (2-).