Which of the following $$0.1 M$$  aqueous solutions will have the lowest freezing point?

Solution :
NOTE: The salt producing highest number of ions will have lowest freezing point.
$${K_2}S{O_4} \to 2{K^ + } + SO_4^{2 - };\,{K_2}S{O_4}$$       gives highest number of particles ( 2 + 1 = 3 ).
Glucose, being non-electrolyte gives minimum no. of particles and hence minimum $$\Delta {T_f}$$  or maximum $$F.$$ $$pt.$$