Select the compound having maximum conductivity in aqueous medium.

Options

A. `[Cr(NH_3)_6]Cl_3`
B. `[Cr(NH_3)_5Cl]Cl_2`
C. `[Cr(NH_3)_4Cl_2]Cl`
D. `[Cr(NH_3)_3Cl_3]`

Answer

To determine which compound has the maximum conductivity in an aqueous medium, we need to analyze the number of ions produced when each compound dissolves in water. Conductivity in solutions is primarily dependent on the concentration of ions; more ions lead to higher conductivity.

### Step-by-Step Solution:

1. **Identify the Compounds**: List the coordination compounds provided in the question.

2. **Understand Dissociation**: Recognize that coordination compounds consist of a coordination sphere and counter ions. The coordination sphere typically does not dissociate into ions, while the counter ions do.

3. **Dissociation of Each Compound**:
- For the first compound, when it dissolves, it dissociates into 1 coordination ion and 3 counter ions (e.g., \( \text{Cr(NH}_3)_6^{3+} + 3 \text{Cl}^- \)), resulting in a total of 4 ions.
- For the second compound, it dissociates into 1 coordination ion and 2 counter ions, resulting in a total of 3 ions.
- For the third compound, it dissociates into 1 coordination ion and 1 counter ion, resulting in a total of 2 ions.
- The fourth compound does not dissociate at all, resulting in 0 ions.

4. **Count the Total Ions**:
- First compound: 4 ions
- Second compound: 3 ions
- Third compound: 2 ions
- Fourth compound: 0 ions

5. **Determine Maximum Conductivity**: Since conductivity is directly proportional to the number of ions in solution, the first compound, which produces the most ions (4), will have the maximum conductivity.

6. **Conclusion**: Therefore, the compound with the maximum conductivity in aqueous medium is the first compound.

### Final Answer:
The compound having maximum conductivity in aqueous medium is the first compound, which dissociates into 4 ions.