19. The molecular formula of the ion is , where X is an element from Group 6A. What is the hybridization of X atom?
(A) sp
(B) sp²
(C) sp³
(D) dsp³
(E) d²sp³

15. The speed of yellow light (from a sodium lamp) in a certain liquid is measured to be 1.92 × 108m/s. What is the index of refraction of this liquid for the light?(A) 1.49 (B) 1.53 (C) 1.56 (D) 1.62 (E) 1.67

16. Which of the following statements is incorrect?(A) The emission spectrum of hydrogen contains a discontinuum of colors.(B) Diffraction produces both constructive and destructive interference.(C) All matter exhibits both particle and wavelike characteristics.(D) Niels Bohr developed a quantum model for the hydrogen atom.(E) None of the above.

17. Which of the following statements is correct?f. An excited atom can return to its ground state by emitting electromagnetic radiation.ff. The energy of an atom is increased when electromagnetic radiation is emitted from it.fff. The energy of electromagnetic radiation increases as its frequency increases.fV. An electron in the n=4 state in the hydrogen atom can go to the n=2 state by emittingelectromagnetic radiation at the appropriate frequency.V. The frequency and wavelength of electromagnetic radiation are inversely proportional toeach other.(A) f, fff, fV, V (B) fff, V (C) f, ff, fff (D) fff, fV, V (E) f, ff, fV

18. Given values of the following acids:What is the order of increasing base strength?(A)(B)(C) (D)(E)

20. Which ion has the largest ionic size among the following?(A) (B) (C) (D) (E)

21. Compare the following molecules, what is the order of decreasing bond order?1. 2. N2 3. (A) 1=2=3 (B) 3＞2＞1 (C) 1＞2＞3 (D) 2＞1=3 (E) 1=3＞2

22. Which of the following statements is correct?(A) BF₃ has 24 total valence electrons, is an exception to the octet rule, and has resonance.(B) BF₃ has 24 total valence electrons, is an exception to the octet rule, and does not haveresonance.(C) BF₃ has 24 total valence electrons, obeys the octet rule, and has resonance.(D) BF₃ has 22 total valence electrons, is an exception to the octet rule, and does not haveresonance.(E) BF₃ has 24 total valence electrons, obeys the octet rule, and does not have resonance.

23. Which chemical process gives beer its brown color?(A) Maillard reaction (B) Caramelization (C) Oxidation of ethanol(D) Hydrolysis of starch (E) All of above

24. Arrange the following bonds in order of decreasing polarity:1. H-H 2. C-F 3. Al-F 4. N-O(A) 1＞2＞3＞4 (B) 3＞2＞4＞1 (C) 1＞3＞2＞4(D) 1＞4＞2＞3 (E) 3＞4＞2＞1

25. The density of a gas is 2 g/L at 3 atm and 27oC. What is the molar mass of the gas (g/mol)?(A) 1.48 (B) 32 (C) 149.6 (D) 9.3 (E) 16.4