68. Which of the following statements is incorrect?
(A) An orbital can accommodate at most two electrons with the same spin quantum number.
(B) The electron density at a point is disproportional to Ψ² at that point.
(C) The quantum number of an electron must be either + .
(D) A 2p orbital is more penetrating than a 2s; i.e., it has a higher electron density near the
nucleus and inside the charge cloud of a 1s orbital.

(E) All of these are incorrect.

64. To cool 500 g of liquid water from 25°C to 0°C, what is the minimum number of ice cubes need to use? Each ice cube contains 20.0 g of water and temperature is -5°C. The enthalpy of fusion of ice is 6.020 kJ/mol; the heat capacity of liquid water is 75.4 J/mol·°C; the heat capacity of solid water is 2.05 J/g·°C.(A) 6 (B) 7 (C) 8 (D) 9 (E) 10

65. fn a coffee-cup calorimeter, 1.60 g NH4NO3 is mixed with 75.0 g water at an initial temperature 25.0oC. After dissolution of the salt, the final temperature of the calorimeter contents was 23.3oC.For the dissolving process, how many of the following thermodynamic functions: ,and , are positive in signs?(A) 0 (B) 1 (C) 2 (D) 3 (E) 4

66. Methanol, a high-octane fuel, is extensively utilized in high-performance racing engines due to its favorable combustion characteristics. To investigate its thermodynamic properties, we cancalculate the change in Gibbs free energy (ΔG°) associated with the combustion reaction ofmethanol when employed as an energy source. What is the G°? (CO2) = -394 kJ, (H2O) = -299 kJ, (CH3OH)= -163 kJ(A) -1358 kJ/mol (B) -1558 kJ/mol (C) -1658 kJ/mol(D) -1758 kJ/mol (E) -1858 kJ/mol

67. fn a high-spin octahedral complex, the metal ion has two more unpaired electrons than in a lowspin octahedral complex. What is the potential metal ion?(A) (B) (C) (D) (E)

69. The solubility of the ionic compound M2X3, having a molar mass of 288 g/mol, is 3.60× g/Lat 25oC. What is the Ksp of the compound at 25℃?(A)(B) (C) (D) (E)

70. What is the pH of a 0.01 M MA solution where MA is a salt that fully dissociates into M⁺ and Ain water? The acid dissociation constant (Ka) for its conjugate acid HA is 1.0×(A) 5 (B) 6 (C) 7 (D) 8 (E) 9

71. What is the equilibrium concentration of HA²- in a 1 M H3A solution with the followingdissociation constants?(A)(B) (C)(D)(E)

72. A certain drug is metabolized in the human body following second-order kinetics, with the rate law given by: Rate= k [D]2where [D] is the concentration of the drug in mg/L, and k is the rate constant in L·. Attime t=0, the drug concentration in the bloodstream is 20.0 mg/L. After 30.0 min, theconcentration drops to 10.0 mg/L.How long will it take for the concentration to drop to 5.0 mg/L?(A) 60.0 min (B) 45.0 min (C) 37.5 min (D) 90.0 min (E) 120.0 min

73. The balanced equation for the reaction of the gases nitrogen dioxide and fluorine is If the first step is the rate-determining step, which of the following expressions correctlyrepresents the rate law?(A) Rate= k [NO2]2[F2] (B) Rate= k [NO2][F2] (C) Rate= k2 [NO2][F](D) Rate= k1 [NO2][F2] (E) None of the above.

74. Consider the ammonia synthesis reaction: where △G° = -31.3 kJ/mol of N2 consumed at 25°CWhich of the following statements correctly predicts the direction of the reaction when =1.00 atm?(A) the system moves to the right(B) the system moves to the left(C) the system is already at equilibrium(D) the system moves to the left if the temperature increases(E) not enough information