Which of the following is the characteristic(s) of secondary valencies according to Werner's theory?

Non-ionizable

The correct answer is option 2. Non-ionizable.

In Werner's theory of coordination compounds:

Primary Valency: This corresponds to the oxidation state of the central metal ion and is satisfied by ions in solution.

Secondary Valency: Also known as coordination number or coordination bonds, these are satisfied by donor atoms of ligands directly bonded to the central metal ion.

Now, focusing on the characteristics of secondary valencies:

Non-ionizable: Secondary valencies are non-ionizable because they involve direct bonding between the central metal ion and the ligands. Unlike primary valencies, which are satisfied by counter ions (ions in solution), secondary valencies are not dissociated into ions themselves.

Therefore, the correct characteristic of secondary valencies according to Werner's theory is Non ionisable.

This means secondary valencies do not dissociate into ions in solution; they are satisfied by the direct bonding between the metal ion and the ligands.