The oxidation number of Fe in `[Fe(CN)_(6)]^(3-)` ion is

Options

A. `+2`
B. `+3`
C. `-2`
D. `-3`

Explanation

To find the oxidation number of Fe in the complex ion \([Fe(CN)_{6}]^{3-}\), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ion and Its Charge**:
The complex ion is \([Fe(CN)_{6}]^{3-}\). The overall charge of the ion is -3.

2. **Assign Oxidation Number to Cyanide (CN)**:
The cyanide ion (CN) has a known oxidation number of -1. Since there are 6 cyanide ions in the complex, we can calculate the total contribution from the cyanide ions.

\[ \text{Total oxidation number from } CN = 6 \times (-1) = -6 \]

3. **Set Up the Equation**:
Let the oxidation number of iron (Fe) be \(x\). The sum of the oxidation numbers in the ion must equal the overall charge of the ion, which is -3.

\[ x + \text{(total oxidation number from } CN) = \text{charge of the ion} \]
Substituting the values we have:

\[ x - 6 = -3 \]

4. **Solve for \(x\)**:
Now, we can solve for \(x\):

\[ x - 6 = -3 \]
\[ x = -3 + 6 \]
\[ x = +3 \]

5. **Conclusion**:
The oxidation number of Fe in the \([Fe(CN)_{6}]^{3-}\) ion is +3.

### Final Answer:
The oxidation number of Fe in \([Fe(CN)_{6}]^{3-}\) is +3.