The number of groups acting only as secondary valencies in the complex `[CoCl_(2)(NH_(3))_(4)]Cl` are

Options

A. 4
B. 2
C. 6
D. None of these

Explanation

To determine the number of groups acting only as secondary valencies in the complex \([CoCl_2(NH_3)_4]Cl\), we need to follow these steps:

### Step 1: Identify the Metal Ion and its Oxidation State
The metal ion in the complex is cobalt (Co). To find its oxidation state, we need to consider the charges of the ligands and the overall charge of the complex.

- The complex \([CoCl_2(NH_3)_4]Cl\) is neutral overall.
- The chloride ions (Cl^-) have a charge of -1 each, and there are 2 of them contributing a total of -2.
- Ammonia (NH₃) is a neutral ligand and does not contribute any charge.

Let \(x\) be the oxidation state of cobalt. The equation for the overall charge is:
\[ x + (-2) + 0 = 0 \]
Thus, \(x = +2\). Therefore, the oxidation state of cobalt in this complex is +2.

### Step 2: Determine the Coordination Number
The coordination number is determined by the number of ligands directly bonded to the metal ion.

- In this complex, there are 2 chloride ions (Cl^-) and 4 ammonia molecules (NH₃).
- Therefore, the total number of ligands attached to cobalt is:
\[ 2 \text{ (from Cl}^-) + 4 \text{ (from NH}_3) = 6 \]

### Step 3: Identify Primary and Secondary Valencies
- **Primary valency** corresponds to the oxidation state of the metal ion, which we found to be +2.
- **Secondary valency** corresponds to the coordination number, which is the number of ligands directly attached to the metal ion. In this case, it is 6.

### Step 4: Determine Groups Acting as Secondary Valencies
In this complex, all the ligands (2 Cl^- and 4 NH₃) are acting as secondary valencies since they are directly bonded to the cobalt ion.

### Final Answer
The number of groups acting only as secondary valencies in the complex \([CoCl_2(NH_3)_4]Cl\) is **6**.

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