Answer:
The correct option is AlFA
Explanation:
There is no element in the periodic table with the symbol of A. Thus, the compound AlFA is wrong and cannot be a salt made from main group elements. CaO is calcium oxide, Al₂O₃ is aluminium oxide and Ca₃N₂ is calcium nitride - all are evidently made from elements from the main groups of the periodic table (except the AlFA)
