1. Which of the following molecules is polar? a) CO₂ b) F₂ c) BF₃ d) NH₃ e) CF₄

2. The angle characteristic of the maximum separation of 3 sets of electrons is

a) 90^o b) 109^o c) 120^o d) 180^o e) 360^o

3. A dilute sugar solution is prepared by mixing 8.0 g of sugar with enough water to give 200 ml of solution. This solution is found to have an osmotic pressure of 2.86 atm. What is the molecular weight of the sugar? The temperature is 25^oC?

4. When 0.125 g of sulfur is finely ground with 3.62 g of camphor (Kf of camphor = 37.7 ^oC/m), the melting point of camphor is lowered by 5.08 ^oC. What is the molecular weight of sulfur in camphor? To what molecular formula does this correspond?

5. Which of the following would have the lowest freezing point?

a) 0.15 m C₁₂H2₂O₁₁(sucrose) b) 0.10 m HC₂H₃O₂ (acetic acid, a weak electrolyte) c) 0.10 m KBr d) 0.10 m CaCl₂ e) 0.05 m H₂SO₄(a strong electrolyte).

 5'. Explain why the correct choice is d) and give the freezing point of each solution.

6. 0.800 g of an unknown nonelectrolyte is dissolved in 50.0g of benzene (Kb = 2.53^oC/m). The resulting solution gives a boiling point elevation of 0.240^oC. Find the molecular weight of the unknown solute.

a) 248 b) 482 c) 169 d) 78 e) 109

 7. Write down the net ionic equation for the reaction between HCl and NaOH.

8. Explain how freezing point depression is used in each of the following. (What is the solute and what is the solvent in each case.)

a) antifreeze, ethylene glycol is added to your radiator. Why is ethylene glycol used?

b) salt scattered on the road in winter. Why is salt used.

c) Melting point is used to check the purity of a drug.