Answer: 1.0 M molecular sucrose (C₁₂H₂₂O₁₁).
Explanation:
1) The depression of the freezing point of a solvent when you add a solute is a colligative property.
2) Colligative properties are those physical properties of solutions that depends on the number of solute particles dissolved into the solution.
3) The relation between the number of solute particles and the depresson of the freezing point is proportional: the greater the number of solute particles the greater the freezing point depression.
4) You need to find the solution with the highest freezing point, this is the solution in which the freezing point decreased the least.
5) Then, that is the solution with least number of solute particles.
6) Since all the given solutions have the same molarity (1.0 M), you only have to deal with the possible ionization of the different solutes.
7) NaCl, CaBr₂, AlBr₃, and KCl are ionic compounds, so each unit of them will ionize into two, three, four, and two ions, respectively, while sucrose, being a covalent compound does not dissociate.
Then, 1.0 M solution of sucrose will have less solute particles than the others, and will exhitibit the lowest freezing point depression, meaning that it will have the highest freezing point of the given solutions.
