Composition of mischmetal is

Options

A. 5% of a lanthanoid metal, 95% of iron and traces of S, C, Ca and Al
B. 95% of an actinoid metal, 5% of iron and traces of S, C, Ca and Al
C. 95% of a lanthanoid metal, 5% of iron and traces of S, C, Ca and Al
D. 95% of a transition metal, 5% of iron and traces of S, C, Ca and Al

Answer

### Step-by-Step Solution:

1. **Understanding Mischmetal**: Mischmetal is an alloy primarily composed of rare earth elements, specifically lanthanides. It is important to recognize that it is not a single element but a mixture of several.

2. **Analyzing the Composition Options**: The question provides several options regarding the composition of mischmetal. We need to evaluate each option based on the known composition of mischmetal.

3. **Identifying the Main Component**: The primary component of mischmetal is lanthanide metals. It is known that mischmetal typically consists of about 95% lanthanide metals.

4. **Identifying the Secondary Component**: The secondary component in mischmetal is iron, which constitutes about 5% of the alloy.

5. **Considering Trace Elements**: In addition to lanthanides and iron, mischmetal also contains trace amounts of other elements such as sulfur, carbon, calcium, and aluminum.

6. **Selecting the Correct Option**: Based on the analysis, the correct composition of mischmetal can be summarized as:
- 95% lanthanide metals
- 5% iron
- Traces of sulfur, carbon, calcium, and aluminum.

7. **Conclusion**: The correct answer is option C: 95% of lanthanide metal, 5% of iron, and traces of sulfur, carbon, calcium, and aluminum.