An amphoteric oxide is an oxide that can act both as an acid and as a base. This means it can react with both acids and bases to form salts and water.

Let's analyze each option to identify which one contains only amphoteric oxides:

Option 1: NO, B₂O₃, PbO, SnO₂

• NO: Neutral oxide (neither acidic nor basic).
• B₂O₃: Acidic oxide (boron oxide).
• PbO: Amphoteric.
• SnO₂: Amphoteric.

This set contains non-amphoteric oxides (NO and B₂O₃), so it does not contain only amphoteric oxides.

Option 2: Cr₂O₃, BeO, SnO, SnO₂

• Cr₂O₃: Amphoteric.
• BeO: Amphoteric.
• SnO: Amphoteric.
• SnO₂: Amphoteric.

All oxides in this set are amphoteric.

Option 3: ZnO, Al₂O₃, PbO, PbO₂

• ZnO: Amphoteric.
• Al₂O₃: Amphoteric.
• PbO: Amphoteric.
• PbO₂: Amphoteric (though it can also act as an oxidizing agent, it is amphoteric).

All oxides in this set are amphoteric.

Option 4: Cr₂O₃, CrO, SnO, PbO

• Cr₂O₃: Amphoteric.
• CrO: Basic oxide (chromium(II) oxide).
• SnO: Amphoteric.
• PbO: Amphoteric.

This set contains a basic oxide (CrO), so it does not contain only amphoteric oxides.

Final Answer: The options with only amphoteric oxides are Option 2 and Option 3.

Related Topics and Formulae

Amphoteric Behavior: Amphoteric substances react with both acids and bases. For example, aluminum oxide reacts as follows:

With acid: $\mathrm{Al}{O}_3+6\mathrm{HCl}\to 2\mathrm{AlCl}{}_3+3H_{2}O$

With base: $\mathrm{Al}{O}_3+2\mathrm{NaOH}\to 2\mathrm{NaAl}{O}_2+H_{2}O$

Common Amphoteric Oxides: BeO, Al₂O₃, Ga₂O₃, ZnO, Cr₂O₃, PbO, SnO, SnO₂, PbO₂.

Periodic Trend: Amphoteric oxides are often found along the diagonal line separating metals and non-metals in the periodic table (e.g., Be, Al, Zn, Sn, Pb).