The formula for copper(II) hydrogen sulfate is Cu(HSO₄)₂. Here's why:

* Copper(II): This tells us the copper ion has a +2 charge (Cu²⁺).

* Hydrogen sulfate: This is the anion formed when sulfuric acid (H₂SO₄) loses one hydrogen ion (H⁺). It has a -1 charge (HSO₄⁻).

To balance the charges, we need two hydrogen sulfate ions (2 x -1 = -2) to match the +2 charge of the copper ion.