Which of the following aqueous solutions containing 10g of solute in each case, has highest melting point?

depression in freezing point, $∆{\mathrm{T}}_{\mathrm{f}}=\mathrm{i}\times {\mathrm{K}}_{\mathrm{f}}\times \mathrm{m} ; \mathrm{i}.\mathrm{e}. ∆{\mathrm{T}}_{\mathrm{f}}\propto \mathrm{i}\times \mathrm{n}$

For NaCl solution, $∆{\mathrm{T}}_{\mathrm{f}}\propto 2\times \frac{10}{58.5}$

For KCl solution, $∆{\mathrm{T}}_{\mathrm{f}}\propto 2\times \frac{10}{74.5}$

For Sugar solution, $∆{\mathrm{T}}_{\mathrm{f}}\propto 1\times \frac{10}{342}$

For Glucose solution, $∆{\mathrm{T}}_{\mathrm{f}}\propto 1\times \frac{10}{180}$

$∆{\mathrm{T}}_{\mathrm{f}}$ is less for Sugar solution, hence it has highest melting point.