The charge on cobalt in `[Co(CN)_(6)]^(-3)` is -

Options

A. `-6`
B. `-3`
C. `+3`
D. `+6`

Answer

To determine the charge on cobalt in the complex ion \([Co(CN)_{6}]^{-3}\), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the components of the complex**:
The complex ion consists of cobalt (Co) and six cyanide (CN) ligands.

2. **Assign oxidation states**:
- Let the oxidation state of cobalt be \(X\).
- The oxidation state of the cyanide ion (CN) is \(-1\).

3. **Set up the equation**:
Since there are six cyanide ions, their total contribution to the charge is:
\[ 6 \times (-1) = -6 \]
The overall charge of the complex ion is \(-3\). Therefore, we can set up the equation:
\[ X + (-6) = -3 \]

4. **Solve for \(X\)**:
Rearranging the equation gives:
\[ X - 6 = -3 \]
Adding 6 to both sides results in:
\[ X = -3 + 6 \]
Thus,
\[ X = +3 \]

5. **Conclusion**:
The oxidation state (and thus the charge) on cobalt in the complex \([Co(CN)_{6}]^{-3}\) is \(+3\).

### Final Answer:
The charge on cobalt in \([Co(CN)_{6}]^{-3}\) is \(+3\).

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