Question

The number of unpaired electrons in Co in the complex ion ${\left[Co{\left(C_2{O}_4\right)}_3\right]}^{3-}$ is [Atomic number of $Co=27$]

• A. $4$
• B. $3$
• C. $Zero$
• D. $5$

Answer 1

The correct option is A $4$

$\left[CO\right(C_2{O}_4{)}_3{]}^{3-}$

Charge of oxalate ion is $-2$

Charge on $CO$ is $CO+(-2)=-3$

$CO=+3$

Hybridisation of $C{O}^{3+}$ is (Refer to Image 1)

$C_2{O}_4^{2-}$ is weal field ligand so forms high spin complex

(Refer to Image 2)

Number of unpaired electrons=$4$.