Which of the following can be prepared by the direct union of elements ?

Options

A. `SF_(6)`
B. `SeF_(6)`
C. `TeF_(6)`
D. All

Answer

To determine which of the following compounds can be prepared by the direct union of elements, we need to analyze each compound individually. The compounds in question are SF6, SEF6, and TEF6.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- The compounds we are analyzing are:
- SF6 (Sulfur Hexafluoride)
- SEF6 (Selenium Hexafluoride)
- TEF6 (Tellurium Hexafluoride)

2. **Analyze SF6**:
- The formation of SF6 can be represented by the reaction:
\[ S + 3F_2 \rightarrow SF_6 \]
- This reaction shows that sulfur (S) directly combines with fluorine (F2) to form SF6. Thus, SF6 can be prepared by the direct union of elements.

3. **Analyze SEF6**:
- The formation of SEF6 can be represented by the reaction:
\[ Se + 3F_2 \rightarrow SEF_6 \]
- This reaction indicates that selenium (Se) directly combines with fluorine (F2) to form SEF6. Therefore, SEF6 can also be prepared by the direct union of elements.

4. **Analyze TEF6**:
- The formation of TEF6 can be represented by the reaction:
\[ Te + 3F_2 \rightarrow TEF_6 \]
- This reaction shows that tellurium (Te) directly combines with fluorine (F2) to form TEF6. Hence, TEF6 can also be prepared by the direct union of elements.

5. **Conclusion**:
- All three compounds (SF6, SEF6, and TEF6) can be prepared by the direct union of their respective elements with fluorine. Therefore, the correct answer is that all of them can be prepared by direct union.

### Final Answer:
All of the compounds (SF6, SEF6, TEF6) can be prepared by the direct union of elements.

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