Exam 2-solutions - Version 141 Exam 2 mccord (50970) 1 This...

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Unformatted text preview: Version 141 Exam 2 mccord (50970) 1 This print-out should have 34 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. McCord CH301 001 10.0 points Which is the most polar molecule? 1. Ar 2. H 2 O correct 3. CH 4 4. CO 2 5. BF 3 6. CF 4 Explanation: H 2 O has angular molecular geometry. It is assymetrical and polar. 002 10.0 points Identify the compound with the most polar bond. 1. PH 3 2. NH 3 correct 3. SbH 3 4. AsH 3 Explanation: Calculate the difference in the electronega- tivities (EN): EN As H 2 . 2- 2 . 2 = 0 . N H 3 .- 2 . 2 = 0 . 8 P H 2 . 2- 2 . 2 = 0 . Sb H 2 . 2- 2 . 1 = 0 . 1 The N H bond is the most polar of these. 003 10.0 points What is the molecular geometry of SbCl 2 5 ? Antimony (Sb) can be an exception to the octet rule, accepting up to twelve electrons. 1. octahedral 2. trigonal bipyramidal 3. square pyramidal correct 4. seesaw 5. square planar Explanation: 004 10.0 points Draw the Lewis structure for CO. 1. b b b b b b b b b b O C correct 2. b b b b b b O b b b b C 3. b b b b b b O b b b b b b O C 4. O b b b b b b b b b b C 5. b b b b b b O b b b b b b C 6. b b b b b b O b b b b b b C 7. O b b C 8. O b b b b b b b b b b C 9. O b b b b b b b b C 10. b b b b b b b b O b b b b b b b b C Explanation: C has 4 valence electrons; O has 6: b b b b C b b b b b b O Total number of valence electrons: C 1 4 e = 4 e O 1 6 e = 6 e 10 e Version 141 Exam 2 mccord (50970) 2 b b b b b b b b b b O C or b b b b O C This configuration gives each atom a com- plete octet. 005 10.0 points White phosphorus is composed of molecules of P 4 in which each P atom is connected to three other P atoms in the shape of a tetrahe- dron. Does it obey the octet rule? 1. Unable to determine 2. Yes correct 3. No Explanation: From the structure P P P P b b b b b b b b it does obey the octet rule. 006 10.0 points In the molecular orbital theory of HCl, the ex- pected bonding molecular orbital (MO) would be 1. MO = H(1 s ) + Cl(3 s ) 2. MO = H(1 s )- Cl(3 s ) 3. MO = H(1 s )- Cl(3 p ) 4. MO = H(1 s ) + Cl(3 p ) correct 5. MO = H(3 p ) + Cl(3 p ) Explanation: H has 1 s valence electron and Cl has 3 p va- lence electrons. Bonding orbitals result from positive (in-phase) overlap of the atomic or- bitals. 007 10.0 points How many and bonds are in the molecule below? C C H N b b H H 1. 5 , 2 correct 2. 6 , 1 3. 5 , 1 4. 7 , 1 5. 6 , 2 Explanation: Sigma bonds are the first bond formed be- tween any two bonded atoms. Any subse- quent bond is a pi bond. 008 10.0 points Which of the following is diamagnetic? 1. O 2 2. O 2 3. O 2 2 correct 4. O + 2 Explanation: All but O 2 2 are paramagentic (possess un- paired electrons)....
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Exam 2-solutions - Version 141 Exam 2 mccord (50970) 1 This...

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