Iron forms iron halides salts by reacting the metal directly with halogen. `FeI_(3)` does not exist. `FeF_(3)` is white soled inspite of five unpaired electrons with `d^(5)` configuration . `FeCl_(3)` is soluble in water and is used as a mordant in dyeing industry.
Q.`FeCl_(3)` solution added to `K_(4)[Fe(CN)_(6)]` gives A while with `KSCN` gives B. A and B respectively are:

Options

A. `Fe_(3)[Fe(CN)_(6)]_(2), Fe(CNS)_(3)`
B. `Fe_(4)[Fe(CN)_(6)]_(2), KFe(CNS)_(3)`
C. `Fe_(4)[Fe(CN)_(6)]_(3), K_(3)[Fe(CNS)_(6)]`
D. `Fe_(4)[Fe(CN)_(6)]_(3), K_(3)[Fe(SCN)_(6)]`

Answer

To solve the question regarding the reactions of FeCl₃ with K₄[Fe(CN)₆] and KSCN, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The first reactant is FeCl₃ (iron(III) chloride).
- The second reactant is K₄[Fe(CN)₆] (potassium ferrocyanide).
- The third reactant is KSCN (potassium thiocyanate).

2. **Reaction of FeCl₃ with K₄[Fe(CN)₆]**:
- When FeCl₃ is added to K₄[Fe(CN)₆], a complex compound is formed.
- The reaction can be represented as:
\[ 4 \text{FeCl}_3 + 3 \text{K}_4[\text{Fe(CN)}_6] \rightarrow \text{Fe}_3[\text{Fe(CN)}_6] + 12 \text{KCl} \]
- The resulting complex is known as Prussian Blue, which is a deep blue color.

3. **Identify Compound A**:
- The complex formed is called iron(III) hexacyanoferrate(II), and its formula is \(\text{Fe}_3[\text{Fe(CN)}_6]\).
- Therefore, Compound A is \(\text{Fe}_3[\text{Fe(CN)}_6]\).

4. **Reaction of FeCl₃ with KSCN**:
- When FeCl₃ reacts with KSCN, it forms another complex.
- The reaction can be represented as:
\[ \text{FeCl}_3 + 3 \text{KSCN} \rightarrow \text{K}_3[\text{Fe(SCN)}_6] + 3 \text{KCl} \]
- The resulting complex is a deep red color.

5. **Identify Compound B**:
- The complex formed is called potassium thiocyanoferrate(III), and its formula is \(\text{K}_3[\text{Fe(SCN)}_6]\).
- Therefore, Compound B is \(\text{K}_3[\text{Fe(SCN)}_6]\).

### Final Answer:
- A is \(\text{Fe}_3[\text{Fe(CN)}_6]\) (iron(III) hexacyanoferrate(II)).
- B is \(\text{K}_3[\text{Fe(SCN)}_6]\) (potassium thiocyanoferrate(III)).