Which relations are not correct for an aqueous dilute solution of K₃PO₄ if its degree of dissociation is $\alpha$?

$$\begin{gathered} \frac{∆P}{P°}=\frac{n_2}{n_1}=\frac{n_2\times M{w}_1\times 1000}{W_1\times 1000}=\frac{Molality\times M{w}_1}{1000} \\ For electrolyte \frac{∆P}{P°}=\frac{Molality\times M}{1000}\times (1+3\alpha ) \\ (M{w}_1=18 for H_{2}O) \\ Also, {\mathrm{\pi }}_{\mathrm{obs}}=\mathrm{C}\times \mathrm{R}\times \mathrm{T}(1+3\mathrm{\alpha }) \\ \therefore \frac{∆\mathrm{P}}{\mathrm{P}°}=\frac{{\mathrm{\pi }}_{\mathrm{obs}}}{\mathrm{RT}}\times \frac{18}{1000} \\ ∆{\mathrm{T}}_{\mathrm{f} \mathrm{obs}}={\mathrm{K}}_{\mathrm{f}}\times \mathrm{molality}\times (1+3\mathrm{\alpha }) \\ \frac{∆\mathrm{P}}{\mathrm{P}°}=\frac{∆{\mathrm{T}}_{\mathrm{f} \mathrm{obs}}\times 18}{{\mathrm{K}}_{\mathrm{f}}\times 100} \\ \mathrm{i}=(1+3\mathrm{\alpha })=\frac{\mathrm{Calculated} \mathrm{molecular} \mathrm{weight}}{\mathrm{Observed} \mathrm{molecular} \mathrm{weight}} \\ \mathrm{Therefore}, \mathrm{molecular} \mathrm{weight} \mathrm{of} {\mathrm{K}}_3{\mathrm{PO}}_4={\mathrm{M}}_{\mathrm{obs}}\times (1+3\mathrm{\alpha }) \end{gathered}$$