Final answer:
The total number of electron domains in an AX2 molecule is 2; these are bonding pairs corresponding to the two atoms (X) bonded to the central atom (A).
Step-by-step explanation:
The question is asking about the total number of electron domains in a molecule with the formula AX2. An electron domain can be either a bonding pair of electrons, which is shared between two atoms, or a lone pair of electrons, which is not shared and belongs to a single atom. In a molecule with the formula AX2 (A being the central atom and X being the atoms bonded to A), there are two atoms bonded to the central atom A, meaning there are two bonding pairs of electrons.
There are no lone pairs of electrons on the central atom in this simple AX2 arrangement. Therefore, the total number of electron domains in an AX2 molecule is 2, corresponding to the two bonding pairs.
Note: This response assumes that AX2 has no lone pairs on the central atom. If lone pairs were present (as in an AX2E or AX2E2 situation), the number of electron domains would be higher.