Question

The correct charge on and co-ordination number of $‘Fe’$ in $K_3[Fe(CN{)}_6]$ is

• A. $+2,4$
• B. $+3,6$
• C. $+2,6$
• D. $+3,3$

Answer 1

Answer: (B)

The correct charge on and co-ordination number of $Fe$ in $K_3\left[Fe(CN{)}_6\right]$ is $+3$ and $6$ respectively.
Since Fe atom is surrounded by six cyanide ligands, the co-ordination number is $6.$
The charge on potassium ion is $+1$ and the charge on cyanide ligand is $-1$.
Let $X$ be the charge on $Fe$.
$3(+1)+X+6(-1)=0$
$3+X-6=0$
$X-3=0$
$X=+3$