Liquation is used when

Options

A. Metal and impurity have low melting point
B. Metal and impurity have high melting point
C. Metal have high melting point and impurity has low melting point
D. Metal has low melting point and impurity has high melting point.

Answer

To solve the question regarding when liquation is used, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process of Liquation**:
- Liquation is a metallurgical process used to separate metals from their ores based on differences in melting points.

2. **Identify the Conditions for Liquation**:
- For liquation to be effective, the metal being extracted must have a **low melting point**.
- Conversely, the impurities present in the ore must have a **high melting point**.

3. **Analyze the Options**:
- The question provides multiple-choice options (A, B, C, D). We need to determine which option correctly describes the conditions under which liquation is used.

4. **Select the Correct Option**:
- Based on our understanding, if the metal has a low melting point (like tin) and the impurities have a high melting point, then liquation is the suitable method for separation.
- Therefore, the correct option is **D**.

### Final Answer:
Liquation is used when the metal has a low melting point and the impurities have a high melting point. Thus, the correct option is **D**.

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