Question

The primary and secondary valencies of cobalt respectively in $\left[ Co \left( NH _3\right)_5 Cl ^{ Cl } Cl _2\right.$ are:

• A. 3 and 5
• B. 2 and 6
• C. 2 and 8
• D. 3 and 6

Answer 1

Answer: (D)

$\left[ Co \left( NH _3\right)_5 Cl \right] Cl _2$
Oxidation number of $Co$ is $+3$.
So primary valency is $3$ .
It is an octahedral complex so secondary valency $6$
or Co-ordination number $6$ .