14.For the reaction A →products, successive half-lives are observed to be 10.0, 20.0 and 40.0 min for an experiment in which [A]₀ = 0.10 M. Based on the information, the concentration of A after 30 min of the reaction is ＿ M
(A) 0.008
(B) 0.30
(C) 0.025
(D) 0.011
(E) 0.0021

10. Consider the following reaction: H2C=CH2(g) + F2(g)→H2FC-CFH2(g), △H = -549 kJ. Please estimate the carbon-fluorine bond energy to be _____ kJ/mol given that the C-C bond energy is 347 kJ/mol, the C=C bond energy is 614 kJ/mol, and the F-F bond energy is 154 kJ/mol. (A) 239 (B)-184(C) -92(D) -327(E) 485

11. Consider three molecules: A, B, and C. Molecule A has a hybridization of sp3. Molecule B has two more effective pairs (electron pairs around the central atom) than molecule A. Molecule C consists of two σ bonds and two π bonds. Thus, which one of the following statements relating to A, B and C is incorrect? (A) Molecule A has a tetrahedral arrangement of electron pairs. (B) Molecule B has a square planar structure. (C) Molecule B has a bond angle of 109.5°. (D) The structure of HCN is similar to C. (E) Molecule C is consistent with a linear arrangement of electron pairs exhibiting sp hybridization.

12. A certain metal fluoride crystalizes in such a way that the fluoride ions occupy simple cubic lattice sites, while the metal ions occupy the body centers of half the cubes. The formula of the metal fluoride is thus_____. (A) MF (B) MF3 (C) MF5 (D) MF4 (E) MF2

13. The solubility of CaCl2 in cold water is 74.5 g per 100.0 g water. Assuming i = 2.6 for CaCl2, the freezing point for a saturated solution of CaCl2 will be _____°C. (A)0 (B) -0.32 (C) -13 (D) -32 (E) -37.4

15. Suppose the reaction system 2HI(g)⇌H2(g) + I2(g) has already reached equilibrium. Which of the following statements correctly predict the effect of each change on the equilibrium position? (A) Additional H2(g) added to the system will shift to the right to obtain the equilibrium. (B) As an exothermic reaction, the system will shift to the right to attain the equilibrium when increasing the system temperature. (C) When iodine gas is removed, the system will shift to the left to achieve the equilibrium. (D) Addition of argon gas into the reaction system will shift to the right to achieve the equilibrium. (E) When volume of the reaction container is doubled, the change will have no effects on its equilibrium.

16. In a 0.10-M aqueous solution of pyridine (Kь = 1.7 × 10-9), the percentage of pyridine (C5H5N) that forms pyridinium ion, C5H5NH+, is _____%. (A) 0.013 (B) 6.4 (C) 4.2 (D) 1.3 (E) 5.5

17. Consider the titration of 40.0 mL of 0.200 M HCIO4 by 0.100 M KOH. After adding 10.0 mL of the KOH solution, the pH of the resulting solution is _____. (A) 1.15 (B) 7.00 (C) 2.72 (D) 0.85 (E) 4.26

18. Which of the following mixtures would result in buffered solutions when 1.0 L of each of the two solutions are mixed? (A) 0.1 M KOH and 0.1 M CH3NH3Cl (B) 0.1 M KOH and 0.2 M CH3NH3Cl (C) 0.1 M KOH and 0.2 M CH3NH2 (D) 0.2 M KOH and 0.1 M CH3NH2 (E) 0.2 M KOH and 0.1 M CH3NH3CI

19. Which of the following substances does not show increased solubility as the pH of the solution becomes more acidic? (A) Hg2Cl2, Ksp = 1.1 × 10-18 (Hg22+ is the cation in solution.) (B) Ag3PO4, Ksp = 1.8 × 10-18 (C) CaCO3, Ksp = 8.7 × 10-9 (D) CdCO3, Ksp = 5.2 × 10-12 (E) Sr3(PO4)2, Ksp = 1.0 × 10-31

20. For the reaction at 800 K: N2(g) + 3F2(g)→2NF3(g), an equilibrium mixture contains the partial pressures of P(nitrogen) = 0.021 atm, P(fluorine) = 0.063 atm, and P(nitrogen trifluoride) = 0.48 atm. The △G° for the reaction at 527°C is thus _____kJ/mol. (A) 17 (B)-50 (C) 50 (D)-17 (E)-71