1. Interpret the data

The empirical formula is $CrCl_3\cdot 3NH_3\cdot 3H_2O$ and the complex is octahedral, so the coordination number of chromium is $6$.

We are told that 1 mole of the compound gives 3 moles of $AgCl$ with excess $AgNO_3$.

This means all 3 chloride ions are present as ionisable chloride ions outside the coordination sphere, because only free $Cl^-$ ions immediately precipitate with $Ag^+$: $Ag^+ + Cl^- \to AgCl\downarrow$

So the complex must be of the form $[Cr(NH_3)_x(H_2O)_y]Cl_3$ with $x+y=6$

Since the empirical formula contains $3NH_3$ and $3H_2O$, the inner sphere is $[Cr(NH_3)_3(H_2O)_3]Cl_3$

2. Primary and secondary valency

• Primary valency of chromium is satisfied by ionisable anions outside the coordination sphere.
• Secondary valency is satisfied by ligands directly coordinated to the metal inside the coordination sphere.

Here, the 3 chloride ions are all outside the coordination sphere, so none of the chloride ions are coordinated to chromium.

Therefore, the number of chloride ions satisfying the secondary valency of the metal ion is $0$

3. Final answer

The required integer is: $\boxed{0}$

4. Comparison with stored answer

Stored correct answer = $0$

This matches the derived answer.