Here's why:

* Mercury (Hg) typically forms two ions: Hg⁺¹ (mercurous ion) and Hg⁺² (mercuric ion).

* Fluorine (F) always forms a -1 ion.

To form a neutral compound, the charges of the ions must balance out.

* Hg2F3 would require a +3 charge on the mercury ions, which is not a common oxidation state for mercury.

The correct formula for mercury(I) fluoride is Hg2F2.

This formula represents the combination of two Hg⁺¹ ions and two F⁻¹ ions.