52. Which working electrode is used for pH measurement?
(A) Ag/AgCl electrode
(B) Calomel electrode
(C) Hg electrode
(D) Glass electrode
(E) Pt electrode

48. In order for the electron to return to the ground state, what must happen? (A) energy is absorbed (B) energy is released (C) no energy change (D) electron is lost (E) electron is gained

49. Which bond is the least polar? (Electronegativities: H = 2.2; N = 3.0; O = 3.5; P = 2.1; S = 2. 5) (A) N-H (B) P-H (C) O-H (D) S-H (E) P-S

50. For a double displacement reaction demonstration in class, a solution of potassium iodide and a solution of lead (II) nitrate were combined. A precipitate was formed as a product. What color was the precipitate? (A) white (B) green (C) yellow (D) black (E) red

51. Which one is WRONG for the safety in the laboratory? (A) Wear eye protection at all times. (B) In the event of contact with acids, immediately flood the affected area with copious quantities of water. (C) Never work alone in the laboratory. (D) Never use your mouth to provide suction. (E) It is legal to flush solutions containing heavy metal ions or organic liquids down the drain.

53. Salt A and salt B were dissolved separately in 100 mL beakers of water. The water temperatures were measured and recorded as shown in the table below: Salt A: initial water temp. 25.1°C final water temp. 30.2°C Salt B: initial water temp. 25.1°C final water temp. 20.0°C Which statement is a CORRECT interpretation of these data? (A) The dissolving of only salt A was endothermic. (B) The dissolving of only salt B was exothermic. (C) The dissolving of both salt A and salt B was endothermic. (D) The dissolving of salt A was exothermic and the dissolving of salt B was endothermic. (E) The dissolving of both salt A and salt B was endothermic.

54. How many moles of oxygen gas, O2, will react with 2 moles of nitrogen monoxide gas, NO, according to the following equation? ___ NO (g) + ___ O2(g) ____ NO2(g) [O2 = 32.00 g/mol; NO = 30.01; NO2 = 46.01] (A) 1 mol (B) 2 mol (C) 3 mol (D) 4 mol (E) none of the above

55. Which pair of Lewis electron-dot symbols correctly depicts the elements: boron and carbon? (A) (B) (C) (D) (E)

56. Which pair of words correctly completes this statement: Ultraviolet light is more dangerous than infrared light because it has more energy. The _______________ of ultraviolet light is _____________ than infrared light. (A) wavelength – longer (B) frequency – higher (C) speed – greater (D) speed – less (E) frequency – lower

57. Which orbital diagram violates the rule "no two electrons can have the same set of four identical quantum numbers"?(A)(B)(C)(D)(E)

58. Which of the following plots correctly describe ideal gas behavior? (A)①②③ (B) only① and② (C) only① and③ (D) only② and③ (E) only①