The oxidation number of cobalt in `K [Co(CO)_(4)]` is

Options

A. `+1`
B. `+3`
C. `-1`
D. `-3`

Explanation

To determine the oxidation number of cobalt in the compound \( K[Co(CO)_4] \), we can follow these steps:

### Step 1: Identify the oxidation states of known elements
- Potassium (K) typically has an oxidation state of \( +1 \).
- Carbon monoxide (CO) is a neutral molecule, so the oxidation state of carbon in CO is \( 0 \).

### Step 2: Set up the equation for the oxidation state of cobalt
Let the oxidation state of cobalt (Co) be \( x \). The compound is neutral, so the sum of the oxidation states must equal zero.

### Step 3: Write the equation
The total oxidation state can be expressed as:
\[ \text{Oxidation state of K} + \text{Oxidation state of Co} + \text{Oxidation state of CO}_4 = 0 \]
Substituting the known values:
\[ (+1) + x + 4(0) = 0 \]

### Step 4: Simplify the equation
This simplifies to:
\[ 1 + x = 0 \]

### Step 5: Solve for \( x \)
To find \( x \), we rearrange the equation:
\[ x = -1 \]

### Conclusion
The oxidation number of cobalt in \( K[Co(CO)_4] \) is \( -1 \).