Consider separate solutions of $0.500{\mathrm{MC}}_2{\mathrm{H}}_5\mathrm{OH}\left(\mathrm{aq}\right),0.100\mathrm{M}{\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2\left(\mathrm{aq}\right),0.250\mathrm{MKBr}\left(\mathrm{aq}\right)$ and $0.125 \mathrm{M}{\mathrm{Na}}_3{\mathrm{PO}}_4\left(\mathrm{aq}\right)\text{ at }{50}^{\circ }\mathrm{C}$. Which statement is true about these solutions, assuming all salts to be strong electrolytes?

All the four solutions have the same amount of the species present in the solution.

$\begin{array}{l}{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\hspace{0.25em} \hspace{0.25em} \hspace{0.25em}\hspace{0.25em}0.500\mathrm{M}\\ 0.100\mathrm{M}{\mathrm{Mg}}_3\left({\mathrm{PO}}_4\right) \hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}0.300\mathrm{M}{\mathrm{Mg}}^{2+}+0.200{\mathrm{PO}}_4^{3-}\\ 0.250\mathrm{MKBr} \hspace{0.25em}\hspace{0.25em}\hspace{0.25em}0.250{\mathrm{MK}}^{+}+0.250\mathrm{M}{\mathrm{Br}}^{-}\\ 0.125\mathrm{M}{\mathrm{Na}}_3{\mathrm{PO}}_4\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} 0.375\mathrm{M}{\mathrm{Na}}^{+}+0.125\mathrm{M}{\mathrm{PO}}_4^{3-}\end{array}$

Since all of them have the concentration of total species, their osmotic pressure will have the same value.