Here's how to break it down:
* Mercury(I): Mercury(I) ions exist as diatomic cations (Hg₂²⁺).
* Phosphate: The phosphate anion is PO₄³⁻.
To balance the charges, you need three mercury(I) ions (3 x 2+ = 6+) and two phosphate ions (2 x 3- = 6-), resulting in the formula Hg₃(PO₄)₂.
