`K_(4)[Fe(CN)_(6)]` is a

Options

A. double salt
B. complex compound
C. neutral molecule
D. none of thes .

Explanation

To determine the nature of the compound \( K_4[Fe(CN)_6] \), we will analyze it step by step.

### Step 1: Identify the Components of the Compound
The compound \( K_4[Fe(CN)_6] \) consists of:
- Potassium ions (\( K^+ \))
- A complex ion \( [Fe(CN)_6]^{4-} \)

### Step 2: Determine the Nature of the Complex Ion
The complex ion \( [Fe(CN)_6]^{4-} \) contains:
- A central metal atom, which is iron (Fe)
- Six cyanide ligands (CN), which are negatively charged

### Step 3: Analyze the Charge of the Compound
The overall charge of the compound is neutral because it is a salt. The potassium ions contribute a total charge of \( +4 \) (since there are four \( K^+ \) ions), and the complex ion \( [Fe(CN)_6]^{4-} \) has a charge of \( -4 \). Thus, the charges balance out:
\[ +4 \text{ (from K)} + (-4) \text{ (from the complex)} = 0 \text{ (neutral)} \]

### Step 4: Determine the Oxidation State of Iron
To find the oxidation state of iron (Fe) in the complex:
- Let the oxidation state of iron be \( x \).
- The cyanide ion (CN) has a charge of \( -1 \), and there are six cyanide ions, contributing a total charge of \( -6 \).

The equation for the charge balance in the complex ion is:
\[ x + (-6) = -4 \]
Solving for \( x \):
\[ x - 6 = -4 \\ x = +2 \]
Thus, the oxidation state of iron in \( [Fe(CN)_6]^{4-} \) is \( +2 \).

### Step 5: Classify the Compound
Now we can classify the compound \( K_4[Fe(CN)_6] \):
- It contains a central metal atom (Fe) surrounded by ligands (CN), which indicates that it is a coordination complex.
- It does not fit the definition of a double salt, as it is not formed from the combination of two different salts.

### Conclusion
The compound \( K_4[Fe(CN)_6] \) is classified as a **complex compound**.