7. A solution contains the ions . Dilute solutions of NaCl, , and Na₂S are available to separate the positive ions from each other. In order to effect separation, the solutions should be added in which order?
(A) Na₂SO₄, NaCl, Na₂S
(B) Na₂SO₄, Na₂S, NaCl
(C) Na₂S, NaCl, Na₂SO₄
(D) NaCl, Na₂S, Na₂SO₄
(E) NaCl, Na₂SO₄, Na₂S

3. Force per impact versus the molar mass of the ideal gas. Which graph represents the plot? (A) (B) (C) (D) (E) none of these

4. Which of the following statements is true concerning ideal gases? (A) the temperature of the gas sample is directly related to the average velocity of the gas particles (B) at STP, 1.0 L of Ar(g) contains about twice the number of atoms as 1.0 L of Ne(8) because the molar mass of Ar is about twice that of Ne (C) a gas exerts pressure as a result of the collisions of the gas molecules with the walls of the container (D) the gas particles in a sample exert attraction on one another (E) all of these statements are false

5. When the equation ； (basic solution) is balanced using the smallest whole- number coefficients, what is the coefficient of ? (A)1(B) 2 (C) 3 (D) 4 (E) 6

6. For the reaction of sodium bromide with chlorine gas to form sodium chloride and bromine, what are the appropriate half-reactions? (ox = oxidation and re = reduction) (A) (B) (C) (D)(E)

8. The sodium salt, NaA, of a weak acid is dissolved in water； no other substance is added. Which of these statements (to a close approximation) is true? (A)(B) (C) (D) (E) none of these

9. Consider two separate solutions of equal concentration. The first solution contains sodium hydroxide, and the second solution contains barum hydroxide. Which solution has the lower pH? (A) the sodium hydroxide solution (B) the barium hydroxide solution (C) the pH's of the two solutions are equal (D) we need to know the concentrations to answer this questio (E) we need to know the volumes to answer this question

10. Identify the strongest basc. (A)(B) CH3OH (C)(D) H2O (E)

11. Which statement is true of a process in which 1 mol of a gas is expanded from state A to state B? (A) when the gas expands from state A to state B, the surroundings are doing work on the system (B) the amount of work done in the process must be the same, regardless of the path (C) it is not possible to have more than one path for a change of state (D) the final volume of the gas will depend on the path taken (E) the amount of heat released in the process will depend on the path taken

12. Which of the following statements is correct? (A) the intemal energy of a system increases when more work is done by the system than heat is flowing into the system (B) the internal energy of a system decreases when work is done on the system and heat is flowing into the system (C) the system does work on the surroundings when an ideal gas expands against a constant external pressure (D) all the statements are true (E) all the statements are false

13. For the vaporization of a liquid at a given pressure, (A) △G is positive at all temperatures (B) △G is negative at all temperatures (C) △G is positive at low temperatures but negative at high temperatures (and zero at some temperature) (D) △G is negative at low temperatures but positive at high temperatures (and zero at some temperature) (E) none of above