Which of the following is expected to be coloured?

Options

A. `Ag_(2)SO_(4)`
B. `CuF_(2)`
C. `MgF_(2)`
D. `CuCl`

Answer

To determine which of the given compounds is expected to be colored, we need to analyze the electronic configurations of the metal ions present in each compound. The presence of unpaired electrons in the d-orbitals of transition metals is crucial, as these unpaired electrons can undergo d-d transitions, leading to the absorption of light and the appearance of color.

### Step-by-Step Solution:

1. **Analyze Ag2SO4:**
- The silver ion (Ag⁺) has an electronic configuration of 4d¹⁰.
- Since there are no unpaired electrons (all d-electrons are paired), Ag⁺ does not undergo d-d transitions.
- **Conclusion:** Ag2SO4 is colorless.

2. **Analyze CuF2:**
- The copper ion (Cu²⁺) has an electronic configuration of 3d⁹.
- The presence of one unpaired electron indicates that Cu²⁺ can undergo d-d transitions.
- **Conclusion:** CuF2 is colored (specifically, it typically appears blue).

3. **Analyze MgF2:**
- The magnesium ion (Mg²⁺) has an electronic configuration of 2p⁶ (no d-electrons).
- Since there are no d-electrons, there can be no d-d transitions.
- **Conclusion:** MgF2 is colorless.

4. **Analyze CuCl:**
- The copper ion (Cu⁺) has an electronic configuration of 3d¹⁰.
- Similar to Ag⁺, Cu⁺ has no unpaired electrons, so it cannot undergo d-d transitions.
- **Conclusion:** CuCl is colorless.

### Final Conclusion:
Among the given compounds, only **CuF2** is expected to be colored due to the presence of unpaired electrons in the Cu²⁺ ion.