19. Which of the following ionic compounds has the largest lattice energy (i.e., the lattice energy most favorable to a stable lattice)?
(A) MgO
(B) CaO
(C) Li₂O
(D) Na₂O
(E) K₂O

15. For the particles listed below with the same kinetic energy, which has the shortest wavelength? (A) electron (B) positron (C) proton (D) α particle (E) neutron

16. In the given reaction coordinate diagram, how many intermediate(s) is/are presented? (A) 0 (B) 1 (C) 2 (D) 3 (E) 4

17. How many nanometers is equal to 7.6 meters? (A) 76 × 107 (B) 76 × 108 (C) 76 × 109 (D) (E)

18. A specific type of nucleus has a half-life of 40 min. How long is required for 80% of the nuclides to decompose? (ln2 = 0.693； ln0.2 = -1.609) (A) 80 min (B) 85 min (C) 95 min (D) 102 min (E) 120 min

20. Determine the hybridization of Cl in . (A) sp (B) sp2 (C) sp3 (D) dsp3 (E) d2sp3

21. Determine, respectively, the proper formulas for sodium tetrachloroaluminate(III) and sodium tetrachlorocobaltate(II). (A) Na(AlCl4)； Na2(CoCl4) (B) Na(AlCl4)； Na(CoCl4) (C) Na2(AlCl4)； Na(CoCl4) (D) Na2(AlCl4)； Na2(CoCl4) (E) Na3(AlCl4)； Na2(CoCl4)

22. What is the sum of all coefficients when the following equation is balanced? NH3(g) + O2(g) → NO2(g) + H2O(g) (A) 6 (B) 14 (C) 17 (D) 21 (E) 23

23. A compound is composed of element X and hydrogen. A mass analysis shows the compound contains 82.35% of X, with three times as many hydrogen atoms as X atoms per molecule. Which element is X? (atomic mass: B = 10.81, C = 12.01, N = 14.01, Al = 26.98, P = 30.97) (A) B (B) C (C) N (D) Al (E) P

24. Which of the following statements is incorrect? (A) Heteronuclear linear molecules can have a net dipole moment. (B) A molecular dipormenant is the dipole moment of the molecular taken as a whole. (C) Ionic bonding results from the transfer of electrons from one atom to another. (D) A molecule with polar bonds must be polar. (E) The distribution of electrons in a polar bond is closer to the more electronegative element.

25. Regarding to the concept of reduction and oxidation, which of the following statements is true? (A) All chemical changes is accompanied by reduction and oxidation. (B) When the atom is oxidized, the size becomes larger. (C) The oxidizing agent is electron donor. (D) Reduction and oxidation can occur independently of each other. (E) Reduction and oxidation describe the gain and loss of electron(s), respectively.