Which of the following has primary valeny `2""?

Options

A. `[Co(NH_(3))_(5)CI]CI`
B. `[Co(NH_(3))_(4)CI_(2)]CI`
C. `[Co(NH_(3))_(3)CI_(3)]`
D. `[Co(H_(2)O)_(4)CI_(2)]CI`

Answer

To determine which of the given compounds has a primary valency (oxidation state) of +2, we will analyze each compound step by step.

### Step-by-Step Solution:

1. **Understanding Primary Valency**:
- Primary valency refers to the oxidation state of the central metal ion in a coordination compound.

2. **Analyzing the First Compound: Cu(NH3)5Cl**:
- The complex can be ionized to give:
\[ \text{Cu(NH}_3\text{)}_5^{2+} + \text{Cl}^- \]
- Here, the oxidation state of copper (Cu) can be calculated as follows:
- Let the oxidation state of Cu be \( x \).
- The amine (NH3) is a neutral ligand, contributing 0 to the charge.
- The chloride ion (Cl) has a charge of -1.
- The overall charge of the complex is +2.
- Therefore, the equation becomes:
\[ x + 0 \times 5 - 1 = +2 \]
\[ x - 1 = +2 \implies x = +3 \]
- Thus, the primary valency (oxidation state) of Cu in this compound is +2.

3. **Analyzing the Second Compound: Co(NH3)4Cl2**:
- The complex can be ionized to give:
\[ \text{Co(NH}_3\text{)}_4^{3+} + 2 \text{Cl}^- \]
- Let the oxidation state of Co be \( x \):
\[ x + 0 \times 4 - 2 = +3 \]
\[ x - 2 = +3 \implies x = +5 \]
- The primary valency of Co in this compound is +3.

4. **Analyzing the Third Compound: CoCl3(NH3)3**:
- The complex can be assumed to have no overall charge:
\[ \text{Co(NH}_3\text{)}_3 + 3 \text{Cl}^- \]
- Let the oxidation state of Co be \( x \):
\[ x + 0 \times 3 - 3 = 0 \]
\[ x - 3 = 0 \implies x = +3 \]
- The primary valency of Co in this compound is +3.

5. **Analyzing the Fourth Compound: Co(H2O)4Cl2**:
- The complex can be ionized to give:
\[ \text{Co(H}_2\text{O)}_4^{3+} + 2 \text{Cl}^- \]
- Let the oxidation state of Co be \( x \):
\[ x + 0 \times 4 - 2 = +3 \]
\[ x - 2 = +3 \implies x = +5 \]
- The primary valency of Co in this compound is +3.

### Conclusion:
The only compound with a primary valency (oxidation state) of +2 is **Cu(NH3)5Cl**.

### Final Answer:
**Option A: Cu(NH3)5Cl has a primary valency of +2.**