How do you arrange these aqueous solutions in order of decreasing freezing point: 0.10 m Na3PO4, 0.35 m NaCl, 0.20 m MgCl2, 0.15 m C6H12O6, and CH3OOH?

Answer 1

Read Freezing Point Depression Section:
http://www.chemistryexplained.com/Ce-Co/Colligative-Properties.html