The correct formula for the ionic compound formed between potassium (K) and oxygen (O) is K₂O. Here's how to determine that:

* Potassium (K) is in group 1 of the periodic table, meaning it has a +1 charge as a cation (K⁺).

* Oxygen (O) is in group 16, meaning it has a -2 charge as an anion (O²⁻).

To form a neutral compound, you need two potassium ions (2 x +1 = +2) to balance the charge of one oxygen ion (-2). This results in the formula K₂O.