Question

Show the coordination number of the metal ion, its oxidation number, the number of electrons in d-orbitals and the number of unpaired electrons in d-orbitals respectively in complex :$\left[Co{\left(H_{2}O\right)}_4{SO}_3\right]Cl$

• A. $6,3,6,4$
• B. $6,3,6,0$
• C. $5,3,6,4$
• D. $5,3,6,0$

Answer 1

Answer: (C)

$5,3,6,4$

Coordination number is the number o dligands in the coordination sphere. Hence, the coordination number of cobalt ion in
$\left[Co{\left(H_{2}O\right)}_4{SO}_3\right]Cl$ is $5$.

Let the oxidation number of $Co$ is $x$.

$x+4\left(0\right)+(-2)+(-1)=0$

$x+0-2-1=0$

$x=3$

The number of electrons in d-orbital is six.

Number of unpaired electrons in d-orbital is $4$ because of $H_{2}O$ is a weak ligand and therefore, pairing of d-electrons in d-orbital is not possible.