84. How many valence electrons are there in an atom with the electron configuration [noble gas]ns ² (n – 1)d ¹⁰ np ³ ?
(A) 2
(B) 3
(C) 5
(D) 10
(E) 15

80. Given Cu2O(s) + 1/2O2(g) → 2CuO(s) , ΔH° = −144 kJ and Cu2O(s) → Cu(s) + CuO(s) , ΔH° = +11 kJ Calculate the standard enthalpy of formation of CuO(s) . (A) −155 kJ (B) +299 kJ (C) +155 kJ (D) −299 kJ (E) −166 kJ

81. Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous.   Overall reaction: MnO4–(aq) + 2H2O(l) + 3Co2+ (aq)MnO2(s) + 3Co3+(aq) + 4OH– (aq) (A) E°cell = –1.23 V, spontaneous (B) E°cell = –1.23 V, nonspontaneous (C) E°cell = 1.23 V, spontaneous (D) E°cell = 1.23 V, nonspontaneous (E) E°cell = –0.05 V, nonspontaneous

 82. The successive packing pattern for a hexagonal closest packed structures is which of the following? (A) ABCABC (B) ABCCBA (C) ABABAB (D) ABAABA (E) AABBAA

83. Identify the missing particle in the following equation:(A) (B) (C) (D)(E) None of the above.

85. For the process CHCl3(s) → CHCl3(l) , ΔH° = 9.19 kJ/mol and the melting point of chloroform is –64 °C. Calculate ΔS° ? (A) 43.9 J/mol/K (B) 53.9 J/mol/K (C) 26.3 J/mol/K (D) 75.2 J/mol/K (E) None of the above.

86. Atomic orbitals developed using quantum mechanics ________. (A) describe regions of space in which one is most likely to find an electron (B) describe exact paths for electron motion (C) give a description of the atomic structure which is essentially the same as the Bohr model (D) allow scientists to calculate an exact volume for the hydrogen atom (E) are in conflict with the Heisenberg Uncertainty Principle

87. Which of the following species requires the highest energy to remove an electron from its valence shell? (A) Na+ (B) F − (C) K (D) Cl− (E) Mg2+

88. A reaction was found to be zero order in X. Increasing the concentration of X by a factor of 5 will cause the reaction rate to ________. (A) remain constant (B) increase by a factor of 25 (C) increase by a factor of 5 (D) increase by a factor of 10 (E) decrease by a factor of the cube root of 5

89. Which of the following is not a factor determining the energy of activation according to the Arrhenius equation? (ABCDE皆送分)(A) temperature (B) frequency of collision of reacting molecules (C) fraction of collisions with effective orientations (D) frequency factor (E) None of the above.

90. A student needs a solution buffered at pH 4.30 ([H+ ] = 5.0×10−5 M). This student can choose from the following weak acids and their salts to prepare the buffer. Which system will own the best buffering capacity? (A) Benzoic acid (Ka = 6.4 × 10-5 ) (B) Chloroacetic acid (Ka = 1.35 × 10-3 ) (C) Propanoic acid (Ka = 1.3 × 10-5 ) (D) Hypochlorous acid (Ka = 3.5 × 10-8 )