Which of the following is amphoteric oxide?

Mn2O7, CrO3, Cr2O3, CrO, V2O5, V2O4

(i) V2O5, Cr2O3

(ii) Mn2O7, CrO3

(iii) CrO, V2O5

(iv) V2O5, V2O4

To determine which of the given oxides are amphoteric, we first need to understand what amphoteric oxides are. Amphoteric oxides can react with both acids and bases, exhibiting properties of both acidic and basic oxides. This characteristic is often seen in oxides of metals that have intermediate oxidation states. Now, let’s analyze the options provided: Mn2O7, CrO3, Cr2O3, CrO, V2O5, and V2O4.

Identifying Amphoteric Oxides

Let’s break down each oxide:

• Mn2O7: This is a highly acidic oxide of manganese, primarily behaving as an acid.
• CrO3: Chromium trioxide is also an acidic oxide, known for its strong oxidizing properties.
• Cr2O3: Chromium(III) oxide is amphoteric. It can react with acids to form chromium salts and with bases to form chromites.
• CrO: Chromium(II) oxide is generally considered basic, reacting with acids but not with bases.
• V2O5: Vanadium pentoxide is primarily acidic, but it can exhibit some amphoteric behavior under certain conditions.
• V2O4: Vanadium(IV) oxide is more basic than acidic, typically reacting with acids.

Evaluating the Options

Now, let’s evaluate the options based on our analysis:

• (i) V2O5, Cr2O3: Cr2O3 is amphoteric, while V2O5 is primarily acidic. This option contains one amphoteric oxide.
• (ii) Mn2O7, CrO3: Both are acidic oxides, so this option does not contain any amphoteric oxides.
• (iii) CrO, V2O5: CrO is basic, and V2O5 is mainly acidic, making this option devoid of amphoteric oxides.
• (iv) V2O5, V2O4: V2O5 is primarily acidic, and V2O4 is more basic, so neither is amphoteric.

Conclusion on Amphoteric Oxides

From our analysis, the only oxide that fits the definition of amphoteric among the options is Cr2O3. Therefore, the correct answer is that Cr2O3 is the amphoteric oxide, which appears in option (i) alongside V2O5. However, it’s important to note that while V2O5 can show some amphoteric characteristics, it is not primarily classified as such. Thus, the best answer focusing solely on amphoteric behavior is Cr2O3.