On reacting excess of CoCl₃. xNH₃ with one mole of AgNO₃, one mole of AgCl is formed. What is the value of 'x'? (Assume that the coordination number is 6).

CoCl₃. XNH₃ gives 1 mole of AgCl. So one Cl^- ion is outside the complex. So 2 Cl^- and 4NH₃ satisfy coordination number 6. 

From the given data the possible complex is

$\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]\mathrm{Cl}$

So x is 4