Two square planar Pt(II) compounds (Pt coordination number 4) have the formulae PtCl2.3NH3 (Y) and PtCl2.4NH3 (Z). With excess AgNO3, Y gives 1 mol of AgCl per mole and Z gives 2 mol. For equimolal aqueous solutions with complete dissociation, the ratio Delta T_f(Z) : Delta T_f(Y) is

JEE Advanced levelSingle correct optionDifficulty 3 of 3cc154

Two square planar Pt(II) compounds (Pt coordination number 4) have the formulae $PtCl X_{2} \cdot 3 NH X_{3}$ (Y) and $PtCl X_{2} \cdot 4 NH X_{3}$ (Z). With excess $AgNO X_{3}$ , Y gives 1 mol of $AgCl$ per mole and Z gives 2 mol. For equimolal aqueous solutions with complete dissociation, the ratio $Δ T_{f} (Z) : Δ T_{f} (Y)$ is

Y has one free chloride, so it is

[Pt (NH X_{3}) X_{3} Cl] Cl

with 2 ions; Z has two, so it is

[Pt (NH X_{3}) X_{4}] Cl X_{2}

with 3 ions. At equal molality

Δ T_{f} \propto i

, so the ratio is

3/2 = 1.50