1 \({\rm{Si}}{{\rm{O}}_{\rm{2}}}\)
2 \({\rm{S}}{{\rm{O}}_{\rm{2}}}\)
3 \({\rm{C}}{{\rm{O}}_{\rm{2}}}\)
4 \({\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{O}}\)
Explanation:
Basicity of oxides decreases in a period from left to right. \({\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{O}}\) is basic oxide, \({\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{,}}\,{\rm{Si}}{{\rm{O}}_{\rm{2}}}\,\,{\rm{and}}\,\,{\rm{S}}{{\rm{O}}_{\rm{2}}}\) are acidic oxides. Alternatively, oxides of metals (e.g., \({\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{O}}\)) are basic, while oxides of non- metals \(\left( {{\rm{S}}{{\rm{O}}_{\rm{2}}}{\rm{,}}\,\,\,{\rm{Si}}{{\rm{O}}_{\rm{2}}}\,\,{\rm{and}}\,\,{\rm{C}}{{\rm{O}}_{\rm{2}}}} \right)\)are acidic.