Answer :
Lithium is in the first column of the periodic table and thus can only form one bond with another atom (its ion is Li+)
Oxygen can form two bonds (as in the dioxygen O2).
Hence if you conbine Li and O it has to be Li2O.
Oxygen can form two bonds (as in the dioxygen O2).
Hence if you conbine Li and O it has to be Li2O.
