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

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

26. Which of the following reactions does not involve oxidation-reduction?(A) CH4 + 3O2→ 2H2O + CO2 (B) PCl3 + Cl2 →PCl5(C) 2Na + 2H2O →2NaOH + H2 (D) MnO2 + 4HCl→ Cl2 + 2H2O + MnCl2(E) CO2 + 2LiOH →Li2CO3 + H2O

27. Calculate the standard change in enthalpy for the reaction and select the correct answer: (A) exothermic reaction(B) endothermic reaction(C) no energy change for this reaction(D) Lack of makes calculation impossible.(E) None of the above.

28. Which of the following can be identified as a set of isotopes?Atomic nuclei containI. 20 protons and 20 neutrons. II. 20 protons and 22 neutrons.III. 21 protons and 19 neutrons. fV. 20 neutrons and 18 protons.V. 21 protons and 20 neutrons.(A) I, IV and II, V (B) I, II and III, fV (C) I, III and II, V(D) II, IV and III, V (E) I, II and III, V

29. Which of the following represents the electron configuration for an excited state of an oxygenatom?(A) 1s22s 22p4 (B) 1s 22s 22p5 (C) 1s22s22p33s1(D) 1s 22s 22p6 (E) 1s22s22p3

30. The nucleus decays to form by producing α and β particles. What is the number of β particles produced?(A) 1 (B) 2 (C) 4 (D) 6 (E) 8

31. A 0.25 kg block oscillates on the end of the spring with a spring constant of 133.3 N/m. If the system has an energy of 6.0 J, then the amplitude of the oscillation is _____.(A) 0.09 m (B) 0.15 m (C) 0.30 m (D) 0.54 m (E) 0.60 m