Question

The species which has four unpaired electron is :

• A. $\left[Co\right(CN{)}_6{]}^{4-}$
• B. $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$
• C. $[FeC{l}_4{]}^{2-}$
• D. $\left[Fe\right(H_{2}O{)}_6{]}^{3+}$

Answer 1

Answer: (C)

$[FeC{l}_4{]}^{2-}$

In $\left[Co\right(CN{)}_6{]}^{4-}$, the $C{o}^{2+}\left(d^7\right)$ ion undergoes $s{p}^3{d}^2$ hybridization to form outer orbital complex with 3 unpaired electrons.

In $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$, the $C{r}^{3+}\left(d^3\right)$ ion undergoes $s{p}^3{d}^2$ hybridization to form outer orbital complex with 3 unpaired electrons.

In $[FeC{l}_4{]}^{2-}$, the $F{e}^{2+}\left(d^6\right)$ ion undergoes $s{p}^3$ hybridization with 4 unpaired electrons.

In $\left[Fe\right(H_{2}O{)}_6{]}^{3+}$, the $F{e}^{3+}\left(d^6\right)$ ion undergoes $s{p}^3{d}^2$ hybridization to form outer orbital complex with 5 unpaired electrons.