The primary and secondary valencies of cobalt respectively in $$Co(NH_3)_5ClCl_2$$ are:

We need to find the primary and secondary valencies of cobalt in $$Co(NH_3)_5ClCl_2$$.

Understand Werner's theory of coordination compounds.

According to Werner's theory:

- Primary valency corresponds to the oxidation state of the metal ion. It is ionisable and is satisfied by negative ions.

- Secondary valency corresponds to the coordination number. It is non-ionisable and represents the number of ligands directly bonded to the metal ion.

Write the coordination compound in proper notation.

$$Co(NH_3)_5ClCl_2$$ can be written as $$[Co(NH_3)_5Cl]Cl_2$$, where:

- The part inside square brackets is the coordination sphere: $$[Co(NH_3)_5Cl]^{2+}$$

- The two $$Cl^-$$ outside are counter ions (satisfy primary valency)

Determine the primary valency (oxidation state).

Let the oxidation state of Co be $$x$$. The overall charge on the complex ion is +2 (to balance two $$Cl^-$$):

$$x + 5(0) + (-1) = +2$$

$$x = +3$$

Primary valency = 3.

Determine the secondary valency (coordination number).

Count the total number of ligands directly attached to Co: 5 $$NH_3$$ molecules + 1 $$Cl^-$$ = 6 ligands.

Secondary valency = 6.

The correct answer is Option (4): 3 and 6.