53. When a system is at equilibrium, ________.
(A)the reverse process is spontaneous but the forward process is not
(B)the forward and the reverse processes are both spontaneous
(C) the forward process is spontaneous but the reverse process is not
(D) the process is not spontaneous in either direction

49. Consider an electrochemical cell based on the reaction:2H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g) Which of the following actions would not change the measured cell potential? (A)lowering the pH in the cathode compartment (B)addition of more tin metal to the anode compartment (C) increasing the tin (II) ion concentration in the anode compartment (D) increasing the pressure of hydrogen gas in the cathode compartment

50. What is the cathode in an alkaline battery? (A)MnO2 (B)KOH (C) Zn powder(D)Mn2O3

51. The standard cell potential ( ) for the reaction below is +0.63 V. At 25 °C, the cell potential for this reaction is ________ V when [Zn2+ ] = 3.0 M and [Pb2+ ] =2.0✖10-4M.Pb2+(aq) + Zn (s) → Zn2+(aq) + Pb (s) (A)0.51 (B)0.86 (C) 0.40(D)0.75

52. The first law of thermodynamics can be given as ________. (A)ΔE = q + w (B)(C) for any spontaneous process, the entropy of the universe increases (D) the entropy of a pure crystalline substance at absolute zero is zero

54. The second law of thermodynamics states that ________. (A)ΔE = q + w (B)ΔH°rxn = Σ nΔH°f (products) - Σ mΔH°f (reactants) (C) for any spontaneous process, the entropy of the universe increases (D) the entropy of a pure crystalline substance is zero at absolute zero

55. ΔS is positive for the reaction ________. (A)2H2 (g) + O2 (g) → 2H2O (g) (B)2NO2 (g) → N2O4 (g) (C) CO2 (g) → CO2 (s)(D)BaF2 (s) → Ba2+ (aq) + 2F- (aq)

複選題56. With thermodynamics, one cannot determine ________. (A)the speed of a reaction (B)the direction of a spontaneous reaction (C) the extent of a reaction (D) the value of the equilibrium constant

57. Photoionization processes (e.g., N2 + hν → N2+ + e-) remove UV of ＜ 150 nm. Which photoreaction is the principal absorber of UV in the 150-200 nm range in the upper atmosphere? (A)N2 + hν → 2N (B)O2 + hν → 2º (C) O3 + hν → O2 + O(D)N2 + O2 + hν → 2NO

58. Which one of the following substances found in the atmosphere will absorb radiation in the infrared portion of the spectrum? (A)N2 (B)O2 (C) Kr(D)H2O

59. What is meant by the salinity of seawater? (A)percent by mass of salt in seawater (B)mass in grams of dry salts present in 1 kg of seawater (C) molality of NaCl in seawater(D)osmotic pressure of seawater