Here's how to determine the oxidation state of sulfur (S) in the hydrogen sulfate ion (HSO₄²⁻):

1. Assign Known Oxidation States:

* Hydrogen (H): +1 (except in metal hydrides)

* Oxygen (O): -2 (except in peroxides and superoxides)

2. Set Up the Equation:

The sum of the oxidation states of all atoms in a polyatomic ion must equal the charge of the ion. Let 'x' be the oxidation state of sulfur:

(+1) + (x) + 4(-2) = -2

3. Solve for 'x':

1 + x - 8 = -2

x = +5

Therefore, the oxidation state of sulfur (S) in HSO₄²⁻ is +5.