Which among the following complex compound will give white precipitate with `BaCl_2(aq)` ?

Options

A. `[Cr(NH_3)_5SO_4]Cl`
B. `[Cr(NH_3)_5Cl]SO_4`
C. `[Co(NH_3)_4SO_4]NO_2`
D. Both (A) and (B)

Answer

To determine which complex compound will give a white precipitate with BaCl₂ (aqueous), we need to analyze the dissociation of each complex and the possible reactions with Ba²⁺ ions.

### Step-by-Step Solution:

1. **Identify the Complex Compounds**:
We have the following complex compounds:
- (i) Cr(NH₃)₅SO₄Cl
- (ii) Cr(NH₃)₅Cl₂SO₄
- (iii) [Co(NH₃)₄SO₄]NO₂

2. **Dissociation of Each Complex**:
- **For (i) Cr(NH₃)₅SO₄Cl**:
- This complex dissociates into Cr(NH₃)₅SO₄²⁺ and Cl⁻.
- When BaCl₂ is added, Ba²⁺ will react with Cl⁻ to form BaCl₂, which is soluble in water. Thus, no precipitate is formed.

- **For (ii) Cr(NH₃)₅Cl₂SO₄**:
- This complex dissociates into Cr(NH₃)₅²⁺ and SO₄²⁻.
- When Ba²⁺ is introduced, it will react with SO₄²⁻ to form BaSO₄, which is insoluble and forms a white precipitate.

- **For (iii) [Co(NH₃)₄SO₄]NO₂**:
- This complex dissociates into Co(NH₃)₄SO₄ and NO₂⁻.
- The Ba²⁺ will react with NO₂⁻ to form Ba(NO₂)₂, which is also soluble. Therefore, no precipitate is formed.

3. **Conclusion**:
- The only complex that forms a white precipitate with BaCl₂ is **Cr(NH₃)₅Cl₂SO₄** because it produces BaSO₄ upon reaction, which is insoluble in water.

### Final Answer:
The complex compound that will give a white precipitate with BaCl₂(aq) is **Cr(NH₃)₅Cl₂SO₄**.