In `CuX_2` , `X` belongs to which group?

Explanation

To determine which group the element `X` belongs to in the compound `CuX_2`, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Oxidation State of Copper (Cu)**:
- In the compound `CuX_2`, the oxidation state of copper (Cu) is known to be +2.

2. **Set Up the Equation for the Oxidation State of X**:
- Let the oxidation state of element `X` be represented as `x`.
- Since there are two `X` atoms in the compound, the total contribution from `X` will be `2x`.

3. **Write the Charge Balance Equation**:
- The overall charge of the compound is neutral (0), so we can write the equation:
\[ \text{Oxidation state of Cu} + \text{Total oxidation state of X} = 0 \]
This translates to:
\[ +2 + 2x = 0 \]

4. **Solve for x**:
- Rearranging the equation gives:
\[ 2x = -2 \]
- Dividing both sides by 2 results in:
\[ x = -1 \]

5. **Determine the Group of Element X**:
- The oxidation state of `X` is -1. Elements that typically have an oxidation state of -1 are halogens.
- Halogens belong to Group 17 (or 7A) of the periodic table.

6. **Conclusion**:
- Therefore, we conclude that the element `X` in `CuX_2` belongs to Group 17 (7A).

### Final Answer:
Element `X` belongs to Group 17 (7A).