所屬科目：研究所、轉學考(插大)◆無機化學
1. Which of the following statements about atomic electronic structure is correct? (A) The effective nuclear charge (Zeff) experienced by a valence electron increases down a group (B) Electrons in $d$ orbitals shield outer s electrons more effectively than inner s electrons (C) The energy of $4s$ orbitals is always lower than that of $3d$ orbitals for all transition-metal atoms (D) For a given shell (same n), $p$ orbitals generally have higher energy than $s$ orbitals due to poorer penetration (E) The Pauli exclusion principle allows two electrons in the same atom to have identical sets of four quantum numbers
2. Which point group best describes staggered ethane, $\mathrm{C}_2\mathrm{H}_6$ (idealized)? (A) $\mathrm{C}_{3\mathrm{v}}$ (B) $\mathrm{T_d}$ (C) $\mathrm{D_{mh}}$ (D) $\mathrm{D}_{3\mathrm{h}}$ (E) $\mathrm{D}_{3\mathrm{d}}$
3. A molecule is chiral if it: (A) Has at least one mirror plane (B) Has an inversion center (C) Has only proper rotation axes (and no improper operations) (D) Has an S4 axis (E) Belongs to any $\mathrm{D_{nh}}$ group
4. Which experimental technique is the most direct method to determine the valence-band electronic structure and density of states of a solid-state material? (A) UV-Vis absorption spectroscopy (B) Infrared (IR) spectroscopy (C) X-ray diffraction (XRD) (D) Ultraviolet photoelectron spectroscopy (UPS) (E) Thermogravimetric analysis (TGA)
5. In a character table, the labels g and u refer to symmetry with respect to: (A) Inversion (i) (B) Reflection in $\sigma_{\mathrm{h}}$ (C) Rotation about $\mathbf{C}_{\mathrm{n}}$ (D) Improper rotation $S_{n}$ (E) Translation along $z$
6. Which of the following correctly describes the oxidation state and electron count of the complex $\left[\mathrm{Fe}(\mathrm{CO})_{2}\right]$? (A) Fe(II), 18 electrons (B) Fe(III), 16 electrons (C) Fe(0), 16 electrons (D) Fe(II), 16 electrons (E) Fe(0), 18 electrons
7. What is the primary role of CuI in the Sonogashira coupling? (A) Acts as a Lewis acid to activate the aryl halide (B) Forms a copper acetylide intermediate from the terminal alkyne (C) Reduces Pd(II) to Pd(0) (D) Stabilizes the phosphine ligand (E) Serves as the main oxidative addition catalyst
8. The number of IR-active CO stretching bands in cis-M(CO)₂L₂ vs trans-M(CO)₂L₂ differs mainly because: (A) The force constant differs only (B) Cis has higher symmetry than trans (C) The reducible representation of CO stretches reduces differently (D) Raman selection rules forbid all CO stretches in cis (E) CO stretches are always degenerate
9. Which statement about phosphine ligands (PR₃) in transition-metal catalysis is correct? (A) Electron-withdrawing phosphine ligands generally accelerate oxidative addition (B) Bulky phosphine ligands tend to stabilize low-coordination-number metal centers (C) Trialkylphosphines (e.g., PMe₃) are weaker σ-donors than triarylphosphines (e.g., PPh₃) (D) Increasing the cone angle of a phosphine ligand always decreases the reaction rate (E) Phosphine ligands mainly function as π-acceptors rather than σ-donors
10. A 0.10 M solution of CH₃COOH has a measured pH = 2.87 at 25 °C. Which of the following pKa values is closest to that of acetic acid? (A) 1.0 (B) 2.0 (C) 3.0 (D) 4.0 (E) 5.0
11. For an octahedral d⁵ high-spin complex, the very weak visible absorption is best rationalized by: (A) Δ₀ is zero (B) Only Laporte-forbidden transitions exist (C) Only spin-forbidden transitions exist (no spin-allowed excited states) (D) Charge-transfer bands dominate and remove all d-d transitions (E) The complex is colorless by definition
12. Which of the following statements correctly defines or describes a *superacid*? (A) A superacid is any acid stronger than sulfuric acid in terms of molarity (B) A superacid is an acid whose Hammett acidity function $(\mathrm{H}_{\mathrm{a}})$ is lower than that of pure sulfuric acid (C) A superacid is an acid that can protonate only strong bases such as amines (D) A superacid always contains fluorine and antimony elements (E) A superacid is an acid that is always stronger than sulfuric acid in water
13. In an $\mathrm{O_h}$ field, the ground term for a $d^2$ free ion $(^{3}F)$ splits into: (A) $\mathrm{A_{1g} + E_g}$ (B) $\mathrm{A_{2g} + T_{1g} + T_{2g}}$ (C) $\mathrm{T_{1u} + T_{2u}}$ (D) $\mathrm{E_g + T_{2u}}$ (E) $\mathrm{A_{2u} + E_u}$
14. Which of the following acids is the *strongest* under aqueous conditions? (A) Chloroacetic acid (B) Acetic acid (C) Phenol (D) Prussic acid (E) Propionic acid
15. Based on the HSAB principle, which of the following metal-ligand pairs is expected to exhibit the strongest covalent bonding character? (A) $\mathrm{Mg^{2+}}$ with $\mathrm{F^{-}}$ (B) $\mathrm{Ag^{+}}$ with $\mathrm{I^{-}}$ (C) $\mathrm{Pt^{2+}}$ with $\mathrm{CN^{-}}$ (D) $\mathrm{Pt^{2+}}$ with $\mathrm{S^{2-}}$ (E) $\mathrm{Al^{3+}}$ with $\mathrm{OH^{-}}$
16. Which factor most often increases $\Delta_{\mathrm{o}}$ for first-row transition metal complexes (all ligand/coordination number/structure equal)? (A) Decreasing oxidation state (B) Changing ligand from $\mathrm{CN^{-}}$ to $\mathrm{I^{-}}$ (C) Increasing metal oxidation state (D) Going from $5d$ to $3d$ metal (E) Lower coordination number always increases $\Delta_{\mathrm{o}}$
17. Which of the following statements correctly describes an intramolecular charge-transfer (ICT) state in a donor-acceptor (D-A) molecule? (A) The ICT state arises from a $\sigma \rightarrow \sigma^{*}$ transition localized on the donor unit (B) The ICT excited state typically involves electron transfer from the acceptor HOMO to the donor LUMO (C) The ICT state usually shows low sensitivity to solvent polarity (D) The ICT transition generally corresponds to electron density shifting from the donor to the acceptor upon excitation (E) Strong ICT character always leads to phosphorescence at room temperature
18. Which of the following statements about lithium (Li) is correct? (A) Li shows the weakest hydration enthalpy among the alkali metals (B) Li readily forms a stable $\mathrm{Li}^{-}$ anion in aqueous solution (C) Li is widely used in Li-ion batteries because of its small ionic radius (D) Li exhibits strong relativistic effects similar to Cesium (E) $\mathrm{Li}_{2}\mathrm{O}$ is acidic in nature
19. Which complex is most likely square planar? (A) $\left[\mathrm{CoF}_{4}\right]^{2-}$ (B) $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ (C) $\left[\mathrm{ZnCl}_{4}\right]^{2-}$ (D) $\left[\mathrm{FeCl}_{4}\right]^{-}$ (E) $\left[\mathrm{MnBr}_{4}\right]^{2-}$
20. Which statement about heterogeneous catalysis is correct? (A) Catalytic activity originates primarily from the bulk atoms of the solid catalyst (B) Adsorption of reactants on the catalyst surface increases the activation energy of the reaction (C) Surface defects, edges, and corners often serve as active sites for catalysis (D) The catalyst is consumed during the reaction to form the product (E) The reaction rate in heterogeneous catalysis is independent of the catalyst surface area
21. Which statement best explains why $4d/5d$ complexes are more often low-spin than $3d$ analogues? (A) $4d/5d$ pairing energy is always larger (B) $\Delta$ is larger due to greater radial extension and overlap (C) $4d/5d$ metals cannot form octahedral complexes (D) Spin-only rule fails for $4d/5d$ metals (E) Only charge-transfer transitions occur
22. Bartlett's classic experiment demonstrated for the first time that a noble gas can form a stable compound. Which of the following statements about this discovery is correct? (A) Bartlett showed that xenon reacts directly with $\mathrm{F}_{2}$ to form $\mathrm{XeF}_{6}$ at room temperature (B) Bartlett reacted xenon with $\mathrm{PtF}_{6}$ to form a xenon fluoroplatinate salt (C) The product of Bartlett's experiment was neutral $\mathrm{XeF}_{2}$ (D) In Bartlett's experiment, $\mathrm{PtF}_{6}$ acted as a reducing agent toward xenon (E) Bartlett demonstrated that xenon is more reactive than krypton under all conditions
23. Two closely overlapping bands often observed for $\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ are most directly explained by: (A) Spin-forbidden transitions only (B) Jahn-Teller distortion splitting $e_g$ levels (C) Tetrahedral contamination (D) Only LMCT (E) Only metal-metal bonding
24. Which of the following statements about fullerenes (C₆₀ & C₇₀) is incorrect ? (A) C₆₀ belongs to the I₁₁ point group and has the highest symmetry among all known fullerenes (B) C₇₀ generally shows broader and red-shifted UV-Vis absorption compared with C₆₀ (C) Both C₆₀ and C₇₀ act as efficient electron acceptors due to their low-lying LUMO levels (D) Each carbon atom in both C₆₀ and C₇₀ is sp³-hybridized (E) C₇₀ has a symmetry point group (D₅ₕ) and an ellipsoidal shape
25. Which of the following steps is NOT involved in the catalytic cycle of the Buchwald-Hartwig coupling? (A) Oxidative addition of an aryl halide to Pd(0) (B) Coordination of the amine to the Pd(II) center (C) Deprotonation to form a Pd-amido intermediate (D) Reductive elimination to form the C-N bond (E) Transmetalation from an organoboron reagent to Pd(II)
26. In the solid state, an oxygen vacancy in an oxide typically acts as: (A) An acceptor producing holes (B) A donor producing electrons (C) A neutral defect with no electronic consequence (D) A defect that always widens the band gap (E) A defect that always creates p-type conductivity
27. Increasing the metal content in ZnO to form Zn-rich ZnO most plausibly leads to: (A) p-type conductivity via zinc vacancies (B) n-type conductivity via donor defects (C) No change due to stoichiometry conservation (D) A molecular (not solid-state) species (E) Metallic conductivity in all cases
28. Which lattice has the highest packing efficiency? (A) Simple cubic (B) Body-centered cubic (C) Face-centered cubic (D) Primitive tetragonal (E) Orthorhombic
29. In a p-n junction under forward bias, current flows mainly because: (A) Electrons and holes recombine at the junction after overcoming reduced barrier (B) The depletion region widens (C) Only holes move; electrons remain fixed (D) Only electrons move; holes remain fixed (E) The band gap collapses to zero
30. In octahedral ligand field theory, which orbital set is stabilized by $\pi$-acceptor ligands? (A) $e_g$ (B) $t_{2g}$ (C) $s$ (D) $p$ (E) all orbitals equally
31. Which of the following statements about periodic trends in electron affinity (EA) and ionization energy (IE) are correct? (A) First ionization energy generally increases from left to right across a period due to increasing effective nuclear charge (B) Electron affinity always becomes more negative down a group because atomic size increases (C) Noble gases have very low ionization energies because of their stable electron configurations (D) The first ionization energy of oxygen is lower than that of nitrogen due to electron-electron repulsion in the $2p$ orbitals (E) Halogens have small electron affinities because their valence shells are already nearly filled
32. Which of the following statements correctly describe the 18-electron rule and its application to organometallic complexes? (A) The 18-electron rule applies equally well to both main-group compounds and transition-metal complexes (B) Complexes that follow the 18-electron rule are typically low-spin and diamagnetic (C) In square-planar $\mathrm{d}^8$ complexes such as $[\mathrm{PtCl}_4]^{2-}$, the metal center satisfies the 18-electron rule (D) $\pi$-acceptor ligands such as CO contribute two electrons per ligand to the metal center (E) The 18-electron rule predicts stability when the metal center achieves a noble-gas-like configuration with 18 valence electrons
33. Which of the following statements about frustrated Lewis pairs (FLPs) are correct? (A) FLPs consist of a Lewis acid and a Lewis base that are prevented from forming a stable adduct due to steric hindrance (B) FLPs activate $\mathrm{H}_{2}$ via oxidative addition at the Lewis acid center (C) Both the Lewis acid and the Lewis base participate cooperatively in the heterolytic cleavage of $\mathrm{H}_{2}$ (D) FLP systems require transition metals to activate small molecules such as $\mathrm{H}_{2}$ or $\mathrm{CO}_{2}$ (E) In FLP chemistry, decreasing steric hindrance generally enhances the ability to activate $\mathrm{H}_{2}$
34. Which configurations commonly show strong Jahn-Teller distortions in $\mathrm{O_h}$? (A) $d^{9}$ (B) high-spin $d^{4}$ (C) low-spin $d^{6}$ (D) $d^{10}$ (E) $d^{0}$
35. Which of the following statements about interhalogen compounds are correct? (A) Interhalogen compounds are generally more reactive than the corresponding dihalogen molecules (B) In $\mathrm{IF}_7$, iodine adopts a pentagonal bipyramidal geometry based on VSEPR theory (C) Interhalogen compounds have lower electronegativity differences than the corresponding halogen molecules (D) Many interhalogen compounds act as strong fluorinating agents (E) The oxidation state of the central halogen in $\mathrm{BrF}_3$ is $+1$
36. Which statements about selection rules are correct for many transition-metal complexes? (A) Laporte rule forbids g →g transitions in centrosymmetric complexes (B) Spin rule forbids transitions that change spin multiplicity (C) Vibronic coupling can relax Laporte-forbidden transitions (D) Spin-orbit coupling can relax spin-forbidden transitions (E) Selection rules make all colored complexes impossible
37. Because boron in organoboranes possesses an empty $p$ orbital, which of the following statements are correct? (A) Organoboranes are strong $\pi$-electron donors toward electrophiles (B) Organoboranes typically behave as Lewis acids and readily accept electron pairs from donors (C) Organoboranes readily form tetrahedral borate species upon reaction with nucleophiles (D) The B-C bond in organoboranes is predominantly ionic (E) The electron-deficient nature of boron makes organoboranes strong Brønsted bases in water
38. Which defects can contribute to electrical conductivity in ionic solids/oxides? (A) Oxygen vacancies (B) Substitutional donor dopants (C) Cation vacancies (acceptors) (D) Perfect stoichiometric lattice always conducts (E) Grain boundaries (in many real ceramics)
39. Which of the following steps correctly occur in the mechanism of Suzuki-Miyaura coupling? (A) Oxidative addition (B) Redox equilibrium (C) Transmetalation (D) Reductive elimination (E) $\beta$-Hydride elimination
40. Which statements about trans vs cis-M(CO)₂L₂ using IR are correct? (A) IR cannot distinguish cis/trans because $\nu(\mathrm{CO})$ is always degenerate (B) Cis/trans distinction can be made by counting $\nu(\mathrm{CO})$ bands in the CO stretching region (C) Trans often shows fewer IR-active $\nu(\mathrm{CO})$ bands than cis (higher symmetry) (D) Raman can sometimes complement IR for assignment (E) The number of observed bands is unrelated to symmetry
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