Question

Correct formula of potassium hexacyanidoferrate(II) is

• A. $K_4\left[Fe\right(CN{)}_6]$
• B. $K_2\left[Fe\right(CN{)}_6]H_{2}O$
• C. $K_3\left[Fe\right(CN{)}_6]$
• D. None of these

Answer 1

The correct option is A $K_4\left[Fe\right(CN{)}_6]$

Here, the compound is anionic complex and the central metal atom is $Fe$ and its oxidation state is +2.
Ligands,
$CN\to \text{It is a anionic monodentate ligand}$
Prefix 'hexa' indicate the six cyanide ligands.
The charge on coordination entity is,
$+2+(-1\times 6)=xx=-4$

So, $K_4\left[Fe\right(CN{)}_6]$ is the correct formula.