【GR0627】 The Solution for GRE Chemistry Practice Test [61-80]

The Solution for GRE Chemistry Practice Test [61-80]

 

추천글 : 【GRE】 Solution for GRE Chemistry Practice Test 

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61. If for Ni(OH)₂ the K_sp is 8.0 × 10^-18, then the expression used to calculate the molar solubility S of Ni(OH)₂ is 

 

 

⑴ answer: A

⑵ S × (2S)² = 8.0 × 10^-18 ⇔ S = (2.0 × 10^-18)^1/3 

 

 

62. Of the following compounds, which reacts most rapidly with water?

 

 

⑴ answer: C

⑵ Acyl chloride is too reactive to react with moisture in the air.

 

 

63. Which of the following compounds will react with (CH₃)₂NH to form an enamine?

 

 

⑴ answer: A

⑵ stork-enamine reaction 

 

 

64. All of the following reactions are examples of the Lewis definition of acid-base behavior EXCEPT 

 

 

⑴ answer: D

⑵ Lewis definition of acid-base doesn't make the change in oxidation number.

⑶ 🄑 and 🄓 are not such examples...

 

 

65. Of the following, which is the weakest oxidizing agent?

 

 

⑴ answer: E

⑵ We need to find the strongest reducing agent.

⑶ MnO₄^- (Mn : +7) : It is about to reduce itself (to +2, for example) and oxidize other materials.

⑷ H₂O₂ (O : -1) : It is about to reduce itself (to -2) and oxidize other materials.

⑸ I₂ (I : 0) : It is about to reduce itself (to -1) and oxidize other materials.

⑹ H⁺ (H : +1) : It is relatively stable.

⑺ Mg (Mg : 0) : It is about to oxidize itself (to +2) and reduce other materials.

 

 

66. Which of the following reactions proceeds via a carbene (or carbenoid) intermediate?

 

 

⑴ answer: A

⑵ 🄐 carbene reaction 

⑶ 🄑 Grignard reagent carbon-carbon coupling reaction 

⑷ 🄒 Wittig reaction 

⑸ 🄓 haloform reaction 

⑹ 🄔 Friedel-Craft acylation 

 

 

67. Which of the following is the major carbocation rearrangement product of the reaction shown below?

 

 

⑴ answer: A

 

 

 

68. The table below shows chromatographic data for the analysis of benzene using an ethylbenzene internal standard. What is the benzene concentration of the sample in μg/mL ?

 

 

⑴ answer: D

⑵ Standard : 10 / 1000 = (50 / 2500) × 1/2

⑶ Sample : 10 / 500 = (x / 2500) × 1/2 ⇔ x = 100

 

 

69. A high-resolution infrared absorption spectrum of a heteronuclear diatomic molecule is shown below. Information about which of the following kinds of energy levels of the diatomic molecule can be obtained from this spectrum?

 

 

⑴ answer: D

⑵ IR spectrum 

 

 

70. The ionization energy of a ground state H atom is 13.6 eV. Given the equation shown below, how much energy is needed to excite an electron in an H atom from a state with quantum number n = 1 to a state with n = 2 ?

 

 

⑴ answer: D

⑵ 13.6 eV × (1 - 1/4) = (3/4) 13.6 eV

⑶ Bohr's model 

 

 

71. All of the following are true about lasers EXCEPT:

 

 

⑴ answer: B

⑵ the principle of the laser 

 

 

 

72. Consider the ground electronic state S₀, the excited singlet state S₁, and the triplet state T₁ of a molecule, shown below. The S₁ → S₀ transition corresponds to 

 

 

⑴ answer: B

 

 

73. Graphite reacts with potassium to produce a compound with the empirical formula KC₈. Of the following, which is the best description of this compound's structure?

 

 

⑴ answer: D

 

 

74. The experimental technique most suited for the determination of the three-dimensional structure of a crystalline solid is 

 

 

⑴ answer: B

 

 

75. In a particular TLC separation, the stationary phase is a C2 plate (= -CH₂CH₃), and the mobile phase is 60% methanol:40% water (v:v). Of the following compounds, which will likely travel the greatest distance during the analysis?

 

 

⑴ answer: A

⑵ The more hydrophilic it is, the further it goes.

⑶ hydrophilicity : acid, base, metal salt ＞ carboxylic acid, amine, amide ＞ alcohol ＞ aldehyde, ketone ＞ alkyl halide ＞ ester ＞ alkene ＞ alkane ＞ alkane

 

 

76. Which of the following statements about sulfur dioxide is true?

 

 

⑴ answer: E

⑵ VSEPR structure : O=S⁺-O^- 

 

 

77. Which of the following statements about polonium, the heaviest Group 16 element, is NOT true?

 

 

⑴ answer: A

⑵ ionization energy

⑶ atomic size 

⑷ alpha decay 

 

 

78. In their metallic form, elements from which of the following groups are usually effective hydrogenation catalysts?

 

 

⑴ answer: B

 

 

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

 

 

⑴ answer: C

 

 

 

80. Which of the following is the product of the series of reactions shown below?

 

 

⑴ answer: C

 

 

입력: 2023.06.12 20:08