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Unformatted text preview: Version 346 Exam 3 mccord (50960) 1 This print-out should have 35 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. mccord-ch301 11am class only - 50960 A-L in UTC 2.112A M-Z in UTC 2.102A R = 0 . 08206 L atm/mol K 001 3.0 points Which of the following statements concerning hybrid orbitals is/are true? I) Hybrid orbitals are energetically degen- erate. II) Any element can form sp 3 d 2 hybrid or- bitals. III) Hybridizing a 2 s and a 2 p orbital would produce one sp hybrid orbital. 1. II, III 2. I only correct 3. II only 4. III only 5. I, II 6. I, III 7. I, II, III Explanation: Statement I is true; hybridization was de- veloped as a theoretical framework to ex- plain the energetic degeneracy of bonds in molecules. Statement II is false; hybridiza- tion involving d orbitals requires access to empty d orbitals, and thus begins in period 3. Statement III is false; the number of or- bitals used to hybridize is always equal to the number of hybridized orbitals, so using a 2 s and a 2 p orbital would result in two sp hybrid orbitals. 002 3.0 points Which of the following bonds is most polar? 1. Br F 2. I F correct 3. Cl F 4. F F Explanation: 003 3.0 points Which of the following is not paramagnetic? 1. C 2 correct 2. N 2 3. O 2 4. B 2 Explanation: C 2 has no unpaired electrons. Nitrous Ox- ide has 1 unpaired electron. Molecular oxygen and B 2 each have 2 unpaired electrons. 004 3.0 points Which of the following does NOT have an angular shape? 1. S 2 3 2. NH 2 3. N 3 correct 4. HOCl 5. ClO 2 Explanation: N 3 is linear. 005 3.0 points Which of the following is expected to boil at the highest temperature? Version 346 Exam 3 mccord (50960) 2 1. C 5 H 12 correct 2. C 2 H 6 3. C 3 H 8 4. CH 4 5. C 4 H 10 Explanation: The boiling point tends to increase with increasing molecular weight. C 5 H 12 has the biggest MW, so it should boil at the highest temperature. 006 3.0 points What is the shape of XeF 4 ? 1. tetrahedral 2. square planar correct 3. trigonal bipyramidal 4. T-shaped 5. seesaw Explanation: There are six regions of electron density (including two lone pairs) around the central atom: Xe F b b b b b b F b b b b b b F b b b b b b F b b b b b b b b b b 007 3.0 points Which of the following is true? 1. Vapor pressure is not affected by temper- ature. 2. Vapor pressure increases as the strength of intermolecular forces increases. 3. Viscosity increases as temperature in- creases. 4. Viscosity increases as the strength of in- termolecular forces increase. correct 5. None of these statements is true. Explanation: 008 3.0 points Which of the following elements would be ex- pected to have the highest electronegativity?...
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This note was uploaded on 11/13/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas at Austin.
- Fall '07