Final answer:
The likely charge on X in the ionic compound with the general formula M₂X₃ is -2.
Step-by-step explanation:
Because the ionic compound must be electrically neutral, it must have the same number of positive and negative charges.
Two aluminum ions, each with a charge of 3+, would give us six positive charges, and three oxide ions, each with a charge of 2-, would give us six negative charges. The formula would be Al2O3.