Question

The charge on the central metal ion in the complex $\left[Ni\right(CO{)}_4]$ is

• A. 2
• B. 4
• C. 3

Answer 1

This is a neutral complex, so the charge on the metal + that on the ligands would be = 0.
We also know that $CO$ is a neutral ligand having a charge of 0.
If $x$ is the oxidation number of $Ni$ then:
$x+4\left(0\right)=0$
$\therefore$ x = 0