The reaction of metals with air, which contains both oxygen and nitrogen, can lead to the formation of both oxides and nitrides. The metals that exhibit this dual reactivity are those with a sufficiently high affinity for nitrogen. Let's analyse the given metals. Lithium (Li) ‌4Li(s)+O2(g)⟶2Li2O(s) ‌6Li(s)+N2(g)⟶2Li3N(s) Lithium forms both an oxide and a nitride. Sodium (Na) and potassium (K) ‌2Na(s)+O2(g)⟶Na2O2(s)‌‌‌ (primarily peroxide) ‌ ‌K(s)+O2(g)⟶KO2(s)‌‌‌ (primarily superoxide) ‌ These alkali metals do not readily form nitrides when burnt in air. Beryllium (Be) ‌2Be(s)+O2(g)⟶2BeO(s) ‌3Be(s)+N2(g)⟶Be3N2(s) Beryllium forms both an oxide and a nitride. Magnesium (Mg) ‌2Mg(s)+O2(g)⟶2MgO(s) ‌3Mg(s)+N2(g)⟶Mg3N2(s) Magnesium forms both an oxide and a nitride. Strontium ( Sr ) ‌2Sr(s)+O2(g)⟶2SrO(s) ‌3Sr(s)+N2(g)⟶Sr3N2(s) Strontium forms both an oxide and a nitride. Barium (Ba) Ba(s)+O2(g)⟶BaO2(s) (primarily peroxide)
3Ba(s)+N2(g)⟶Ba3N2(s) Barium forms both an oxide (peroxide) and a nitride. The metals from the list that form both an oxide and a nitride are lithium (Li), beryllium (Be), magnesium (Mg), strontium ( Sr ), and barium (Ba).