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自然科學 大學

大學普化 方智化學第六題

ow Na k 7 CI o se Br Chapter 2 化學鍵結 AH -C=CH 升二技插大 3. Brigma The bond between the carbon atoms in acetylene (HCCH) consists of ) (A)6 pi electrons (B)4 pi and 2 sigma electrons (C)6 sigma electrons (D)2 pi and 4 sigma electrons (E)3 pi and 3 sigma B) B 7.(BCDE) electrons. 【84 成大化學) 14.(B) 20.(C) 4. E ) (A)NO; [83 中興A] Which of the following has a triple bond? (B)O2 (C)C12 (D)CO; (E)CN-. Which one of the following element pairs has the lowest electronegativity (B) 27.(D) 34. (C) C) 41.(CD) 1 G difference and thereby is the least polan? Få 10 323.49 B) (84 5% *ILI) -) 48. (A) 6. NET 2 > 2 D) 58. (D) 62. (B) 69. NO+ D Obind (219) O 发 (A)SeF (B)Seci (QKBr (D/NaCl (E)KAT. 11 The compound Sio does not exist as a discrete molecule while CO2 does. This can be explained because ly 2 ep 3 15 aly zp (A)the Si–O bond is unstable (B)The Lewis structure of SiO has an even number of electrons (C)The SiO2 is a solid while CO, is a gas (D)the 3p orbital of the Si has little overlap with the 2p of the 0 (E)none of the these. V MOJT 515 1 - 4 40 (成大】 Yi (4 0 atom) (86 58*A] 7. In order to explain the valence observed for many of the elements 0 -Si-O in terms of electron configurations, it is often useful to look at electronis staies slightly different from the ground state in comparing 0-41-0 the ground state of boron with the state more useful to describe 0 bonding, the number of unpaired electrons goes from (A)1 to 2 (B)1 to 3 (C)3 to 4 (D)3 to 5 (E)none of the above. (集 (80 清大B) Which of the following compounds should not exist? ( (, 【85 成大A】 alf 566-32 Cle 32-8-24 2-89 cild 14 1 he atoms 83 中興A) mm bove. B 29 p. 1 1 be a ) \CHE > ? (A)Na,P (B)(NH4),PO, CIPO. DPH xH)POCI,, Maspal sput 中興A] Pa zorgt O 15412 = 1) O-P- 5 5+12= 1) 10-4 - 13 13-12=1 -- cl-P-0

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自然科學 大學

求解答案是否正確

Multiple-choice questions: (70 points) write the letter of statement that is not true: 1. A.B.U The Drude Model: (a) It is a classical approach using concepts from the kinetic theory of gases. (b) A relaxation-time approximation is used where the probability of collision is l/t. (c) No forces act on the electrons in between collisions. (d) It predicts accurately the electronic heat capacity of metals. 2. The Sommerfeld Model: (a) The crystal potential is replaced by an average Coulomb potential. (b) The separation of states is so close that a continuum model can be applied. (c) The electrons are highly localized due to a strong crystal potential. (Q) The energy of the highest occupied state at 0 K is the Fermi energy. 3. Density of states in k-space, N(k): (a) N(k) is determined by the boundary value conditions. (b) For lattices in any dimensions, N(k) is constant in k-space. (C) N(k) depends on the direction and magnitude of k. (d) It is directly proportional to the volume of the crystal. E影響, c 4. The Fermi surface of a metal: (a) is responsible for many of the transport properties of the metal, (b) depends on the nature of the chemical bonds, (c) is always a sphere, (d) can involve mixing of electron orbitals. ✓ 5. The conductivity of a material () increases with the mobility of its carriers, (b) increases with the density of carriers, (C) it is inversely proportional to the energy gap. cogu changes with temperature. 6. BID Plasmons: (a) They are an important characteristic of the Sommerfeld electron gas model. (b) Plasmons occur spontaneously in metals. (c) They are related to charge density oscillations. (d) The Plasmon energy is typically of the order of 10 eV. The Fermi energy Ef in intrinsic semiconductors 8) is usually close to y E, at OK (b) it ACiD. can increase or decrease with temperature depending on the ratio of hole and electron effective masses, (c) it represents the point at which the probability of occupation is 12, even though there may not been any states with that energy, (d) its value relative to the electronic bands must remain unaffected in the presence of defects or interfaces.

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