Here's why:
* Mercurous refers to the mercury(I) ion, which has the formula Hg₂²⁺. This is because mercury(I) ions exist as a dimer, meaning two mercury atoms are bonded together.
* Carbonate is the polyatomic ion CO₃²⁻.
To balance the charges, we need one Hg₂²⁺ ion and one CO₃²⁻ ion, resulting in the formula Hg₂CO₃.
