(a) Classify following oxides as neutral, acidic, basic or amphoteric:

CO, B₂O₃, SiO₂, CO₂, Al₂O₃, PbO₂, Tl₂O₃

(b) Write suitable chemical equations to show their nature.

SiO₂= Acidic

Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium silicate.

SiO₂ + 2NaOH → 2Na₂SiO₃ + H₂O

→ Tl₂O₃ = Basic

Being basic, it reacts with acids to form salts. It reacts with HCl to form thallium chloride.

Tl₂O₃ + 6HCl → 2TlCl₃ + 3H₂O

→ CO = Neutral

→ CO₂ = Acidic

Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium carbonate.

CO₂ + 2NaOH → Na₂CO₃ + H₂O

→ B₂O₃ = Acidic

Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium metaborate.

B₂O₃ + 2NaOH → 2NaBO₂ + H₂O

→ PbO₂ = Amphoteric

Amphoteric substances react with both acids and bases. PbO₂ reacts with both NaOH and H₂SO₄.

PbO₂ + 2NaOH → Na₂PbO₃ + H₂O

2PbO₂ + 2H₂SO₄→ 2PbSO₄ + 2H₂O + O₂

→ Al₂O₃= Amphoteric

Amphoteric substances react with both acids and bases. Al₂O₃ reacts with both NaOH and H₂SO₄.

Al₂O₃ + 2NaOH → NaAlO₂

Al₂O₃ + 3H₂SO₄→ Al₂(SO₄)₃ + 3H₂O