Question

Co-ordination compounds contain central metal atom/ion and ligands.

Primary valency of central metal atom/ion in $\left[Co{\left(N{H}_3\right)}_6\right]{Cl}_3$ is :

• A. $3$
• B. $6$
• C. $4$
• D. $9$

Answer 1

The correct option is A $3$

Primary valencies are those which a metal posses in the formation of its simple salts and it corresponds to its oxidation state. The primary valency of the metal ion is generally satisfied by a negative ion.

Here in this compound, negative ions are $C{l}^{-}$ ions. There are 3 $C{l}^{-}$ ions, so primary valency is 3.

Hence option $A$ is correct.