The secondary valency of chromium in `[Cr(en)_(3)]Cl_(3)` is

Options

A. `6`
B. `3`
C. `2`
D. `4`

Explanation

To determine the secondary valency of chromium in the complex `[Cr(en)_(3)]Cl_(3)`, we can follow these steps:

### Step 1: Identify the Coordination Complex
The given complex is `[Cr(en)_(3)]Cl_(3)`. Here, `Cr` represents chromium, and `en` stands for ethylenediamine, which is a bidentate ligand.

### Step 2: Understand the Ligands
Ethylenediamine (en) is a bidentate ligand, meaning that each en molecule can form two bonds with the chromium ion. Since there are three en ligands in the complex, we need to calculate the total number of bonds formed.

### Step 3: Calculate the Total Number of Bonds
Since each bidentate ligand (en) forms two bonds with the metal center (Cr), and there are three such ligands, the total number of bonds formed is:
\[ \text{Total Bonds} = \text{Number of Ligands} \times \text{Bonds per Ligand} = 3 \times 2 = 6 \]

### Step 4: Determine the Secondary Valency
The secondary valency is defined as the total number of bonds formed by the metal with the ligands. In this case, since we calculated that there are 6 bonds formed by the three bidentate en ligands, the secondary valency of chromium in `[Cr(en)_(3)]Cl_(3)` is 6.

### Conclusion
Thus, the secondary valency of chromium in the complex `[Cr(en)_(3)]Cl_(3)` is **6**.

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