a. Classify following oxides as neutral, acidic, basic or amphoteric: `CO,B_(2)O_(3),SiO_(2),CO_(2),Al_(2)O_(3),PbO_(2),Tl_(2)O_(3)`.
b. Write suitable chemical reaction to show their nature.

Explanation

(a) Neutral oxides : CO : Acidic oxides : `B_(2)O_(3), SiO_(2), CO_(2)`
Amphoteric oxides : `Al_(2)O_(3), PbO_(2)` Basic oxide : `Tl_(2)O_(3)`
(b) (i) Being acidic `B_(2)O_(3), SiO_(2)` and `CO_(2)` react with alkalis to form salts.
`underset("anhydride")underset("Boric")(B_(2)O_(3)) + 2NaOH rarr underset("Sod. metaborate")(2NaBO_(2) + H_(2)O) , underset("Silica")(SiO_(2))+2NaOH overset(Delta)rarrunderset(" Sod. silicates ")(Na_(2)SiO_(3))+H_(2)O`
`underset(" Carbon dioxide ")(CO_(2)) + 2NaOH rarr underset(" Sod. carbonate ")(Na_(2)CO) + H_(2)O`
(ii) Being amphoteric, `Al_(2)O_(3)` and `PbO_(2)` react with both acids and bases.
`underset("Alumina")(Al_(2)O_(3)) + 2NaOH overset("Fuse")rarr underset(" Sod. meta-aluminate ")(NaAlO_(2)) + H_(2)O , Al_(2)O_(3) + 3H_(2)SO_(4) rarr Al_(2)(SO_(4))_(3) + 3H_(2)O`
`underset(" Lead dioxide ")(PbO_(2)) + 2NaOH rarr underset(" Sod. plumbate ")(Na_(2)PbO_(3)) + H_(2)O , 2PbO_(2) + 2H_(2)SO_(4) rarr 2PbSO_(4) +2H_(2)O + O_(2)`
(iii) Being basic, `Tl_(2)O_(3)` dissolves in acids.
`Tl_(2)O_(3) + 6 HCl rarr 2TlCl_(3) + 3H_(2)O`.