The IUPAC name of the coordination compound $$\text{K}_3[\text{Fe}(\text{CN})_6]$$ is

The compound contains the ionic part $$K^+$$ and the complex anion $$[\text{Fe}(\text{CN})_6]^{3-}$$. According to IUPAC rules, the name of the cation is written first, followed by the name of the anionic complex.

Step 1 - Name of the cation:
Each $$K^+$$ ion is named simply as potassium. With three such ions balancing the charge, the name remains “potassium” (numerical prefixes are not used for simple cations).

Step 2 - Oxidation state of the metal in the complex anion:
Let the oxidation state of Fe be $$x$$.
Cyanide carries a charge of $$-1$$. There are 6 CN⁻ ligands, contributing $$6(-1) = -6$$.
The overall charge on the complex ion is $$-3$$.
Hence, $$x + (-6) = -3 \;\Rightarrow\; x = +3$$.

Step 3 - Name of the anionic complex:
• For an anionic complex, the metal ends with “-ate”; for iron, the stem becomes ferrate.
• Six CN⁻ ligands are indicated by the prefix “hexa-cyano-”.
Putting these together with the oxidation state: “hexacyanoferrate(III)”.

Step 4 - Full IUPAC name:
Combining the cation and anion names, we obtain
Potassium hexacyanoferrate(III).

Option B which is: Potassium hexacyanoferrate (III).