What is the Werner secondary valence in complex $[CoCl(NH_3)_5]^{2+} 2Cl^-$?

6

The correct answer is Option (4) → 6

In Werner’s theory:

• Primary valence = oxidation state
• Secondary valence = coordination number (number of ligands directly attached to the metal)

For the complex:

$[\text{CoCl}(\text{NH}_3)_5]^{2+}\, 2\text{Cl}^-$

Inside the coordination sphere, Co is bonded to:

• 5 NH₃ ligands
• 1 Cl⁻ ligand

Total ligands attached = 6