Which of the following has the lowest freezing point?

Among the following $0.1 \ m$ aqueous solutions,which one will exhibit the lowest boiling point elevation,assuming complete ionization of the compound in solution?

The molal elevation constant of water is $0.51 \ K \, kg \, mol^{-1}$. The boiling point of $0.1 \ m$ aqueous $NaCl$ solution is nearly .......... $^oC$.

Of the following four aqueous solutions,the total number of those solutions whose freezing point is lower than that of $0.10 \, M \, C_{2}H_{5}OH$ is (Integer answer).
$(i)$ $0.10 \, M \, Ba_{3}(PO_{4})_{2}$
$(ii)$ $0.10 \, M \, Na_{2}SO_{4}$
$(iii)$ $0.10 \, M \, KCl$
$(iv)$ $0.10 \, M \, Li_{3}PO_{4}$

The degree of dissociation of a $0.2 \, m$ aqueous solution of a weak acid $HX$ is $0.3$. If $K_f$ for water is $1.85 \, K \, kg \, mol^{-1}$,then the freezing point of the solution will be approximately ........... $^oC$.

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