State true or false :
The oxidation number of cobalt in `K[Co(CO)_(4)]` is -1

Explanation

To determine whether the statement "The oxidation number of cobalt in K[Co(CO)₄] is -1" is true or false, we can follow these steps:

### Step 1: Identify the components of the complex
The complex is K[Co(CO)₄]. Here, K is potassium, Co is cobalt, and CO is carbon monoxide, which acts as a neutral ligand.

### Step 2: Determine the oxidation state of potassium
Potassium (K) is an alkali metal and has a fixed oxidation state of +1.

### Step 3: Determine the oxidation state of the CO ligands
Each CO molecule is a neutral ligand, meaning it has an oxidation state of 0. Since there are four CO ligands, their total contribution to the oxidation state is 4 × 0 = 0.

### Step 4: Set up the equation for the oxidation state of cobalt
Let the oxidation state of cobalt be represented by x. The overall charge of the complex ion [Co(CO)₄] is 0 (since it is part of a neutral compound with potassium). Therefore, we can set up the equation:

\[ \text{Oxidation state of K} + \text{Oxidation state of Co} + \text{Oxidation state of CO ligands} = 0 \]

Substituting the known values:

\[ +1 + x + 0 = 0 \]

### Step 5: Solve for x
Now, we can solve for x:

\[ x + 1 = 0 \]

\[ x = -1 \]

### Conclusion
The oxidation number of cobalt in K[Co(CO)₄] is -1. Therefore, the statement is **True**.

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