【GR0627】 The Solution for GRE Chemistry Practice Test [81-100]

The Solution for GRE Chemistry Practice Test [81-100]

 

추천글 : 【GRE】 Solution for GRE Chemistry Practice Test 

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81. Which of the following is a step in the mechanism of the hydrolysis of the ester shown below?

 

 

⑴ answer: A

⑵ saponification 

 

 

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

 

 

⑴ answer: C

⑵ wittig reaction 

 

 

83. For the reaction shown below, the experimental rate law is rate = k[A]². Which of the following is the integrated rate law for this reaction? 

 

 

⑴ answer: E

⑵ second-order reaction 

 

 

84. Consider the mechanism shown below for oxidation of NO by O₂. Based on the steady state approximation, which of the following conditions is true for this mechanism?

 

 

⑴ answer: C

⑵ semi-steady state assumption 

 

 

 

85. Given the information below, the concentrations of B and C and the control (thermodynamic or kinetic) of the system at short and long times are described by which of the following?

 

 

⑴ answer: A

 

 

86. In CrF₂ (s), the coordination of the six F's around the Cr is a distorted octahedron with four short and two long Cr-F bonds. Which of the following best explains this observation?

 

 

⑴ answer: C

 

 

87. Each of the following molecules can act as a chelating ligand EXCEPT

 

 

⑴ answer: D

⑵ In 🄐, 🄑, 🄒, and 🄔, a pair of Ns can provide lone pairs of electrons.

 

 

88. Which of the following is NOT a desirable property of an indicator to be used in a complexometric titration that involves EDTA?

 

 

⑴ answer: B

 

 

89. Which of the following statements about complexes that form between metals, Mⁿ⁺, and EDTA in aqueous solutions is true?

 

 

⑴ answer: E

⑵ quantification of metal cations using EDTA (MgY2-)

 

MgY^2- + Mⁿ⁺ → MY^n-4 + Mg²⁺

 

⑶ 🄐 : MgY^2- is denpendent on pH.

⑷ 🄑 : As metal-EDTA complexes are not colored, Eriochrome Black T or Calmagite is needed to quantify Mg²⁺.

⑸ 🄒 : Metal-EDTA complexes are often 1:1 in stoichiometry.

⑹ 🄓 : As metal-EDGA complexes are quite stable, the remaining Mg²⁺ can be credibly manipulated.

 

 

90. Which of the following compounds exists in stereoisomeric forms?

 

 

⑴ answer: C

⑵ cis/trans isomers 

 

 

91. All of the following are recognized as pathways that can reduce the CO₂ level in the atmosphere EXCEPT

 

 

⑴ answer: C

⑵ cellular respiration 

 

 

92. Which of the following is a wavefunction, ψ(r, θ, ϕ), for an s electron?

 

 

⑴ answer: A

⑵ s electron has symmetricity, independent of θ and ϕ.

 

 

93. Due to electron-electron interactions, it is not possible to obtain exact solutions to the Schrödinger equation for many-electron atoms. One approach that addresses this difficulty uses 

 

 

⑴ answer: D

⑵ Slater's rule is adopted to address effective nuclear charges in the situation of many-electon atoms.

 

 

94. Of the following linear combinations of atomic orbitals centered on two atoms, A and B, which best represents the ground-state molecular orbital for the hydrogen molecule, H₂?

 

 

⑴ answer: A

⑵ N(1s_A + 1s_B) : bonding molecular orbital

⑶ N(1s_A - 1s_B) : anti-bonding molecular orbital 

 

 

95. Acetic acid is extracted from ether into water. Which of the following actions will NOT increase the fraction of acetic acid removed from ether?

 

 

⑴ answer: D

⑵ 🄐 pH of the water increases. → Acetic acid becomes charged acetate ion. → Acetate ion is more acquired due to charge.

⑶ 🄑 Volume of water increases. → pH change of water due to acetic acid decreases. → Acetate ion is more acquired.

⑷ 🄒 Volume of ether decreases. → Acetic acid is more acquired due to diffusion.

⑸ 🄓 Benzoic acid is added. → Benzoic acid decreases pH of the water. → Acetate ion is less acquired.

⑹ 🄔 Ammonia is added. → Ammonia increases pH of the water. → Acetate ion is more acquired.

 

 

96. The ionic strength of an aqueous 0.10 M Pb(NO₃)₂ solution is 

 

 

⑴ answer: C

⑵ NO₃^- does not make sediments in most cases.

 

 

97. Which two of the following are the propagation steps in the allylic bromination of cyclohexene shown below?

 

 

⑴ answer: E

⑵ X₂ + Δ → radical substitution reaction 

 

 

98. The transformation shown below is carried out by which of the following reagents?

 

 

⑴ answer: B

⑵ anti-Markovnikov's rule in alkene hydration 

 

 

99. Which of the following could carry out the conversion shown below?

 

 

⑴ answer: A

⑵ Grignard reagent formation reaction → carbon-carbon coupling reaction 

 

 

100. Vitamin B₁₂, an essential nutrient for humans, contains which of the following elements?

 

 

⑴ answer: A

 

입력: 2023.06.18 13:11