Among $a)N{a}_{2}O;b)MgO;$ $c)A{l}_2{O}_3;$ $d)P_2{O}_5$ and $e)C{l}_2{O}_7,$ the most basic, most acidic and amphoteric oxide can be 

Metal being electropositive in nature form basic oxide .non metals being electronegative in nature from acidic oxides. So, the extent of acidity and basicity in oxide depends on electropositive and electronegative nature of elements.