Which of the following complex(s) will have blue colour solution or ppt ?

Options

A. `[Cu(NH_(3))_(4)]SO_(4)`
B. `[Cu(NH_(3))_(4)](OH)_(2)`
C. `Co[Hg(SCN)_(4)]`
D. `K_(3)[Co(NO_(2))_(6)]`

Answer

To determine which of the given complexes will have a blue color solution or precipitate, we will analyze each complex based on their chemical composition and known color characteristics.

### Step-by-Step Solution:

1. **Identify the complexes:**
- Complex 1: Cu(NH4)2(SO4)2 (commonly written as Cu(NH4)2(SO4))
- Complex 2: Cu(NH3)4(OH)2
- Complex 3: Co(Hg)(SCN)4
- Complex 4: K3[Co(NO2)6]

2. **Analyze Complex 1: Cu(NH4)2(SO4)2**
- This complex contains copper (Cu) which is known to form blue-colored complexes, especially in the presence of ammonia or ammonium ions.
- **Conclusion:** This complex will have a blue color solution or precipitate.

3. **Analyze Complex 2: Cu(NH3)4(OH)2**
- This complex also contains copper and ammonia. Copper(II) complexes with ammonia typically exhibit a blue color.
- **Conclusion:** This complex will have a blue color solution or precipitate.

4. **Analyze Complex 3: Co(Hg)(SCN)4**
- This complex contains cobalt (Co) and thiocyanate (SCN). Cobalt complexes can also show blue colors, particularly in certain coordination environments.
- **Conclusion:** This complex will have a blue color solution or precipitate.

5. **Analyze Complex 4: K3[Co(NO2)6]**
- This complex contains cobalt and nitro groups. Cobalt complexes with nitro groups are typically yellow or green, not blue.
- **Conclusion:** This complex will not have a blue color solution or precipitate.

### Final Answer:
The complexes that will have a blue color solution or precipitate are:
- Complex 1: Cu(NH4)2(SO4)2
- Complex 2: Cu(NH3)4(OH)2
- Complex 3: Co(Hg)(SCN)4

Thus, the correct options are **A, B, and C**.

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