Which of the following pair is an amphoteric oxide ?

Options

A. `V_2O_5, Cr_2O_3`
B. `Mn_2O_7 , Cr_2O_3`
C. `CrO, V_2O_5`
D. `V_2O_5, Vr_2O_4`

Explanation

To determine which pair of oxides is amphoteric, we need to analyze the oxidation states of the metals in each oxide and their corresponding acidic or basic nature.

### Step-by-Step Solution:

1. **Understanding Amphoteric Oxides**:
- Amphoteric oxides can react with both acids and bases. They typically have a medium oxidation state.

2. **Analyzing the Given Options**:
- We have the following pairs to analyze:
- A) V2O5 and Cr2O3
- B) Mn2O7 and Cr2O3
- C) CrO and V2O5
- D) V2O5 and V2O4

3. **Evaluating Option A: V2O5 and Cr2O3**:
- **V2O5**: Vanadium in V2O5 has an oxidation state of +5. This is considered amphoteric.
- **Cr2O3**: Chromium in Cr2O3 has an oxidation state of +3. This is also considered amphoteric.
- **Conclusion**: Both V2O5 and Cr2O3 are amphoteric. This pair is valid.

4. **Evaluating Option B: Mn2O7 and Cr2O3**:
- **Mn2O7**: Manganese in Mn2O7 has an oxidation state of +7. This is acidic.
- **Cr2O3**: As established, Cr2O3 is amphoteric.
- **Conclusion**: This pair is not amphoteric since Mn2O7 is acidic.

5. **Evaluating Option C: CrO and V2O5**:
- **CrO**: Chromium in CrO has an oxidation state of +2. This is basic.
- **V2O5**: As established, V2O5 is amphoteric.
- **Conclusion**: This pair is not amphoteric since CrO is basic.

6. **Evaluating Option D: V2O5 and V2O4**:
- **V2O5**: As established, V2O5 is amphoteric.
- **V2O4**: Vanadium in V2O4 has an oxidation state of +4. This is basic.
- **Conclusion**: This pair is not amphoteric since V2O4 is basic.

7. **Final Conclusion**:
- The only pair that is amphoteric is **Option A: V2O5 and Cr2O3**.

### Final Answer:
The pair that is an amphoteric oxide is **V2O5 and Cr2O3**.