13. Which of the following molecules has a central atom that is dsp³ hybridized?
(A) CO₂,
(B) C₂H₂,
(C) NH₃,
(D) PCl₅,
(E) SF₆

9. The vapor pressure of liquid ethane thiol, C2H5SH, is 100 mmHg at 260 K. A sample of C2H5SH is placed in a closed, evacuated 557 mL container at a temperature of 260 K. It is found that all of the C2H5SH is in the vapor phase and that the pressure is 69 mm Hg. If the volume of the container is reduced to 213 mL at constant temperature, how many of the following statements are correct? ▪Only ethane thiol vapor will be present ▪Some of the vapor present before reducing the volume will condense ▪Liquid ethane thiol will be present ▪The pressure in the container will be 100 mmHg  ▪No condensation will occur (A) 1, (B) 2, (C) 3, (D) 4, (E) 5

10. Which of the following laws describes "The entropy of the universe is always increasing" ?  (A) First Law of Thermodynamics, (B) Second Law of Thermodynamics, (C) Third Law of Thermodynamics, (D) Fourth Law of Thermodynamics, (E) Hess's Law

11. What is the formula for the compound that crystallizes with a cubic closest packed array of sulfur ions, and that contains zinc ions in of the tetrahedral holes and aluminium ions in of the octahedral holes?  (A) ZnAlS, (B) ZnAlS2, (C) Zn8Al2S, (D) ZnAl2S4, (E) ZnAl4S8

12. Two drops of indicator HIn , where HIn is yellow and In⁻ is blue, are placed in 100.0 mL of 0.10 M HCl. The solution is titrated with 0.10 M NaOH. At what pH will the color change (yellow to greenish yellow) occur?  (A) 5.0, (B) 6.0, (C) 7.0, (D) 8.0, (E) 9.0

14. How many principal energy levels contain electrons in a manganese atom? (A) 1, (B) 2, (C) 3, (D) 4, (E) 5

15. What is the bond order for a C₂ molecule?  (A) 0, (B) 1, (C) 2, (D) 3, (E) 4

16. Which of the following molecules is an exception to the octet rule?  (A) BF₃, (B) H₂O, (C) KBr, (D) CF₄, (E) N₂

17. Calculate the solubility of solid Ag₂SO₄ in a AgNO₃ solution of 0.20 M.  (A) (B) 0.20 mol/L, (C)(D) (E)

18. Which of the following electromagnetic radiations has the largest wavelength?  (A) X ray, (B) Infrared, (C) γ ray, (D) Visible light, (E) Ultraviolet

19. What information below is needed to calculate the wavelength of a hydrogen atom excited from level n=2 to n=5? (i) the electromagnetic spectrum; (ii) the change in energy from n = 2 to n = 5; (iii) Planck's constant (iv) mass of the hydrogen electron; (v) the speed of light (A) (i) & (iii) & (v), (B) (ii) & (iii) & (v), (C) (i) & (ii) & (iv), (D) (ii) & (iii) & (iv) & (v), (E) all of them