Answer:
4 electrons
Step-by-step explanation:
[CoBr₆]³⁻ contains Cobalt as the central metal ion and 6 bromide atoms are bonded to the metal as ligands.
Bromide is a weak field ligand and thus pairing of the electrons will not take place and the complex, [CoBr₆]³⁻ is a high spin complex.
The oxidation number of Co in [CoBr₆]³⁻ is +3.
The Electronic configuration of Co³⁺ in [CoBr₆]³⁻ (d⁶) in a weak field octahedral environment is [tex]t_{2g}^4 e_g^2[/tex]
Number of unpaired electrons = 4 electrons
