You're asking about the oxidation state of the sulfate ion (SO₄²⁻). Here's how to figure it out:

Understanding Oxidation States

* Oxygen: Oxygen usually has an oxidation state of -2, unless it's in a peroxide (like H₂O₂) where it's -1.

* The Sum: The sum of the oxidation states of all atoms in a polyatomic ion must equal the charge of the ion.

Calculating the Oxidation State of Sulfur

1. Oxygen's contribution: Four oxygen atoms each have a -2 oxidation state, for a total of -8.

2. The ion's charge: The sulfate ion has a charge of -2.

3. Sulfur's contribution: To make the total oxidation state -2, the sulfur atom must have an oxidation state of +6.

Therefore, the oxidation state of sulfur in SO₄²⁻ is +6.