Final answer:
The most likely formula for the compound formed between potassium and element X is KX. The correct option is D.
Step-by-step explanation:
The most likely formula for the compound formed between potassium and element X is KX.
Magnesium reacts with a certain element to form a compound with the general formula MgX. Since magnesium and potassium belong to the same group in the periodic table (Group 1), they have similar chemical properties. Therefore, it is likely that the compound formed between potassium and element X would have a similar formula as the compound formed between magnesium and element X.
In the case of magnesium, it forms the compound MgX, where X represents another element. So, the most likely formula for the compound formed between potassium and element X would be KX.````