【GR0627】 The Solution for GRE Chemistry Practice Test [41-60]

The Solution for GRE Chemistry Practice Test [41-60]

 

추천글 : 【GRE】 Solution for GRE Chemistry Practice Test 

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41. The molecular geometry of IF₅ is 

 

 

⑴ answer: A

 

 

 

42. At a given temperature, the vapor pressure of SiF₄ is significantly higher than that of SF₄. The major physical basis for the difference in vapor pressure is that SiF₄ and SF₄ have different 

 

 

⑴ answer: A

⑵ dipole moment 

 

 

43. Which of the protons indicated will be observed as a doublet in the ¹H NMR spectrum of the molecule shown below?

 

 

⑴ answer: B

⑵ spin-spin splitting

⑶ a : singlet

⑷ b : doublet 

⑸ c : triplet

⑹ d : quartet 

⑺ e : triplet 

 

 

44. Which of the following is the major product of the reaction shown below?

 

 

⑴ answer: D

⑵ alkyne anti-addition  

 

 

45. Acyclic conjugated dienes may exist in two conformations, as shown below. Based on differences in steric strain, which of the following dienes has the greatest preference for the s-trans conformation?

 

 

⑴ answer: C

 

 

46. Which of the following substances is in equilibrium with cyclopentanone and HCN shown below?

 

 

⑴ answer: C

⑵ carbonyl reaction type 2

 

 

 

47. All of the following elements have at least one isotope that is not radioactive EXCEPT

 

 

⑴ answer: D

 

 

48. Based on the molecular orbital model, which of the following is the number of unpaird electrons and the bond order for the superoxide ion, O₂^-?

 

 

⑴ answer: B

⑵ See the electron configuration of O₂.

 

 

⑶ # of unpaired electron = 1 with an unpaired electron in either π_2px or π_2py.

⑷ bond order = (6 - 3) / 2 = 1.5 

 

 

49. For a system at thermal equilibrium, which of the following is the Boltzmann distribution expression for the probability, p_i, that a single molecule is in the ith energy state with energy ε_i?

 

 

⑴ answer: E

⑵ Maxwell-Boltzmann speed distribution 

 

 

50. Which of the following expressions involving fugacity, f, is correct as P → 0?

 

 

⑴ answer: A

 

 

51. Sodium acetate spontaneously crystallizes out of a supersaturated solution on standing or on the addition of a seed crystal. Which of the following is true for the thermodynamic quantities of this system for this process?

 

 

⑴ answer: A

⑵ spontaneous → ΔG ＜ 0

⑶ crystallization → ΔS ＜ 0

⑷ ΔG = ΔH - TΔS ＜ 0 ⇔ ΔH ＜ 0 

 

 

52. If ideal gas behavior is assumed, for which of the following reactions does ΔH equal ΔU?

 

 

⑴ answer: E

⑵ ΔH = ΔU + Δ(PV) = ΔU + (Δn)RT = ΔU

⑶ ∴ Δn_gas = 0

 

 

53. PbF₂(s), which is slightly soluble in water, is dissolved in water to form a saturated solution in equilibrium with solid PbF₂. Which of the following will cause additional PbF₂(s) to dissolve?

 

 

⑴ answer: A

⑵ NO₃^- would decrease the amount of Pb²⁺ by forming Pb(NO₃)₂ (s).

 

 

54. Which of the following is the major product of the reaction shown below?

 

 

⑴ answer: D

⑵ S_N2 substitution reaction by amine nucleophile

 

 

55. Which of the following is the product of the reaction shown below?

 

 

 

⑴ answer: B

⑵ alkene ozonolysis : Separate the double bonds and connect each with a carbonyl group (=O).

 

 

56. Which of the following is the major product of the reaction shown below?

 

 

⑴ answer: B

⑵ Grigard reagend carbon-carbon coupling reaction for epoxide : The steric effect is considered.

 

 

57. Which of the following is the major organic product of the reaction shown below?

 

 

⑴ answer: C

⑵ saponification + carboxylic acid LAH reaction 

 

 

58. Given the expression below, what is the value of (∂U / ∂V)_T for an ideal gas undergoing isothermal expansion? (PV = nRT for an ideal gas.)

 

 

⑴ answer: E

⑵ The internal energy solely depends on the temperature. 

 

 

59. The heat of fusion of ice is 333.5 J/g. The entropy change for the water when freezing 5.0 g of water at 0 ℃ and 1 atm pressure is

 

 

⑴ answer: E

⑵ ΔS = ΔQ / T = -333.5 J/g × 5.0 g / 273.15 K = -6.10 J/K

 

 

60. Many enzyme reactions follow the Michaelis-Menten rate law shown below, where V and K_m are constants and [S] is the concentration of substrate that is undergoing a catalyzed reaction. When [S] ≫ K_m, what is the apparent order of the reaction?

 

 

⑴ answer: A

⑵ It reaches the saturation velocity.

⑶ Michaelis-Menten rate law 

 

입력: 2023.06.11 10:49