Which of the following aqueous solutions has the highest boiling point?

Expression of elevation boiling point:

${\mathrm{\Delta T}}_{\mathrm{b}}={\mathrm{iK}}_{\mathrm{b}}\mathrm{m}$

'i' is the van't Hoff factor. More is the number of ions, more is the value of i, hence greater will be the boiling point

(a) no. of particles in 0.1 M KNO₃:

  $\left({\mathrm{KNO}}_3\rightleftharpoons {\mathrm{K}}^{+}+{\mathrm{NO}}_3^{-}\right)=2$

(b) no.of particles in 0.1 M Na₃PO₄:

 $\left({\mathrm{Na}}_3{\mathrm{PO}}_4\rightleftharpoons 3{\mathrm{Na}}^{+}+{{\mathrm{PO}}_4}^{3-}\right)=$4 

(c) no. of particles in 0.1 M BaCl₂:

 $\left({\mathrm{BaCl}}_2\rightleftharpoons {\mathrm{Ba}}^{2+}+2{\mathrm{Cl}}^{-}\right)=3$ 

(d) no. of particles in 0.1 M K₂SO₄:

  $\left({\mathrm{K}}_2{\mathrm{SO}}_4\rightleftharpoons 2{\mathrm{K}}^{+}+{\mathrm{SO}}_4^{2-}\right)=3$