Which of the following is not obtained by direct reaction of constituent elements

Options

A. `XeF_(2)`
B. `XeF_(4)`
C. `XeO_(3)`
D. `XeF_(6)`

Explanation

To determine which compound is not obtained by the direct reaction of its constituent elements, we need to analyze the reactions mentioned in the transcript.

### Step-by-Step Solution:

1. **Identify the Compounds**:
The question refers to several compounds, including XCF4, XCF6, and XCO3. We need to understand how these compounds are formed.

2. **Direct Reaction Definition**:
A direct reaction of constituent elements means that the elements combine in a straightforward manner to form a compound without any intermediate steps or reactions.

3. **Analyze XCF4 Formation**:
The transcript mentions that XCF4 is formed by the direct reaction of X and F2 (fluorine). This indicates that XCF4 can be obtained directly from its elements.

4. **Analyze XCF6 Formation**:
Similarly, XCF6 is formed from X and F2 as well. The transcript suggests that XCF6 can also be obtained directly from its constituent elements.

5. **Analyze XCO3 Formation**:
The formation of XCO3 is mentioned in the context of a reaction involving water and hydrofluoric acid (HF). This suggests that the formation of XCO3 does not occur directly from its constituent elements but rather through a series of reactions.

6. **Conclusion**:
Based on the analysis, XCO3 is not obtained by the direct reaction of its constituent elements, as it requires additional reactants (water and HF) to form.

### Final Answer:
XCO3 is not obtained by the direct reaction of its constituent elements.