Assertion: Aluminothermy is used for extraction of chromium form chromium oxide.
Reason: Alumina has a high melting point.

Options

A. If both (A) and ( R) are correct and ( R) is the correct explanation of (A).
B. If both (A) and ( R) are correct, but ( R) is not the correct explanation of (A).
C. If (A) is correct, but ( R) is incorrect.
D. If (A) is incorrect, but ( R) is correct.

Answer

To analyze the given question, we need to evaluate both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Aluminothermy is used for extraction of chromium from chromium oxide."
- Aluminothermy is indeed a method used to extract metals from their oxides using aluminum as a reducing agent. It is commonly used for the extraction of chromium from chromium oxide (Cr2O3).

2. **Understanding the Reason**:
- The reason states that "Alumina has a high melting point."
- Alumina (Al2O3) does have a high melting point (around 2050 °C). This property is important in metallurgy but does not directly explain why aluminothermy is used for chromium extraction.

3. **Evaluating the Relationship**:
- Both the assertion and the reason are correct statements. However, the reason provided does not serve as a valid explanation for the assertion. The use of aluminothermy is based on aluminum's ability to reduce chromium oxide, not directly related to the melting point of alumina.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not explain the assertion, the correct answer is that the assertion is correct, and the reason is also correct, but it is not the correct explanation of the assertion.

### Final Answer:
- Both the assertion and reason are correct, but the reason is not the correct explanation for the assertion. Therefore, the answer is option B.

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