What are constituents of 'Mischmetal'?

Options

A. La, Fe
B. La, Ce
C. Fe. Ce
D. Ce, Cu

Explanation

**Step-by-Step Solution:**

1. **Understanding Mischmetal**: Mischmetal is an alloy primarily composed of rare earth elements. The term "Mischmetal" itself is derived from German, meaning "mixed metal."

2. **Composition of Mischmetal**: The typical composition of Mischmetal includes a significant proportion of cerium and lanthanum. Specifically, it usually contains around 50% cerium and 25% lanthanum, along with smaller amounts of other rare earth elements like neodymium and praseodymium.

3. **Analyzing the Options**: The question provides four options regarding the constituents of Mischmetal:
- Option 1: Lanthanum and Iron
- Option 2: Lanthanum and Cerium
- Option 3: Iron and Cerium
- Option 4: Cerium and Copper

4. **Evaluating Each Option**:
- **Option 1 (Lanthanum and Iron)**: Incorrect, as iron is not a primary constituent of Mischmetal.
- **Option 2 (Lanthanum and Cerium)**: Correct, as both lanthanum and cerium are the main components of Mischmetal.
- **Option 3 (Iron and Cerium)**: Incorrect, as iron is not a significant part of Mischmetal.
- **Option 4 (Cerium and Copper)**: Incorrect, as copper is not a constituent of Mischmetal.

5. **Conclusion**: The correct answer is **Option 2: Lanthanum and Cerium**.

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