Final answer:
The compound resulting from the reaction of potassium with oxygen is potassium oxide, with the formula K₂O. This follows from the crisscross method of balancing charges in the formation of ionic compounds.
Step-by-step explanation:
When potassium reacts with oxygen, the resulting compound is potassium oxide, represented by the formula K₂O. During the reaction, potassium reacts with diatomic oxygen (O₂) in a combination reaction. The balance between positive and negative charges must be considered since potassium forms K+ ions and oxygen forms O²- ions.
By using the crisscross method, we can determine that two potassium atoms will combine with one oxygen atom to form the ionic compound K₂O, instead of KO, KO₂, or K₂O₂. As a result, the correct answer to what compound forms when potassium reacts with oxygen is A) K₂O.