According to Werner's coordination theory, which of the following...

According to Werner's coordination theory, the secondary valency (coordination number) of Pt(IV) is 6. The given empirical formulas can be represented as coordination complexes by satisfying the secondary valency of 6 with ammonia molecules and chloride ions:

$\mathrm{PtCl_4 \cdot 6NH_3} \Rightarrow [\mathrm{Pt(NH_3)_6}]Cl_4$ (yields 5 ions, 4 precipitable $Cl^-$ ions)

$\mathrm{PtCl_4 \cdot 5NH_3} \Rightarrow [\mathrm{Pt(NH_3)_5Cl}]Cl_3$ (yields 4 ions, 3 precipitable $Cl^-$ ions)

$\mathrm{PtCl_4 \cdot 4NH_3} \Rightarrow [\mathrm{Pt(NH_3)_4Cl_2}]Cl_2$ (yields 3 ions, 2 precipitable $Cl^-$ ions)

$\mathrm{PtCl_4 \cdot 2NH_3} \Rightarrow [\mathrm{Pt(NH_3)_2Cl_4}]$ (yields 0 ions, 0 precipitable $Cl^-$ ions)

Since $[\mathrm{Pt(NH_3)_2Cl_4}]$ is a neutral complex, it does not ionize in aqueous solution. Therefore, it exhibits the lowest molar conductance (almost zero) and fails to give a white precipitate of $\mathrm{AgCl}$ upon the addition of excess $\mathrm{AgNO_3}$.

Answer: $\mathrm{PtCl_4 \cdot 2NH_3}$