Consider the following transformation :
`2CuX_(2) overset("Room temperature")(to) 2CuX+X_(2) (uarr)`
Then `X^(-)` can be:

Options

A. `F^-, Br^-`
B. `Cl^-,Br^-`
C. `CN^-,I^-`
D. `Cl^-,F^-`

Answer

To solve the problem, we need to analyze the given transformation:

**Transformation:**
\[ 2 \text{CuX}_2 \overset{\text{Room temperature}}{\rightarrow} 2 \text{CuX} + \text{X}_2 \]

1. **Identify the Compounds:**
- The transformation involves copper compounds with a halogen or a similar element represented by \( X \).
- \( \text{CuX}_2 \) indicates that each copper atom is bonded to two \( X \) atoms.

2. **Analyze the Products:**
- The products are \( 2 \text{CuX} \) and \( \text{X}_2 \).
- This suggests that \( 2 \text{CuX}_2 \) decomposes to form \( 2 \text{CuX} \) and releases \( \text{X}_2 \).

3. **Determine the Nature of \( X \):**
- The reaction indicates that \( X \) is likely a diatomic molecule in its elemental form (as seen in \( \text{X}_2 \)).
- Common candidates for \( X \) could be halogens (like \( \text{Cl} \), \( \text{Br} \), \( \text{I} \)), or other diatomic species.

4. **Consider Possible Values for \( X \):**
- If \( X \) were to be a halogen, we can test common halogens:
- For \( X = \text{Cl} \):
\[ 2 \text{CuCl}_2 \rightarrow 2 \text{CuCl} + \text{Cl}_2 \]
- For \( X = \text{Br} \):
\[ 2 \text{CuBr}_2 \rightarrow 2 \text{CuBr} + \text{Br}_2 \]
- For \( X = \text{I} \):
\[ 2 \text{CuI}_2 \rightarrow 2 \text{CuI} + \text{I}_2 \]

5. **Conclusion:**
- The transformations for \( \text{Cl} \), \( \text{Br} \), and \( \text{I} \) all support the reaction.
- Therefore, \( X^- \) can be \( \text{Cl}^- \), \( \text{Br}^- \), or \( \text{I}^- \).
- Given the options, if \( \text{I} \) is specifically mentioned in the options, then \( X^- \) can be \( \text{I}^- \).

Thus, the answer is that \( X^- \) can be \( \text{I}^- \).