EXAM2 - Version 284 Exam 2 mccord(50970 This print-out...

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Version 284 – Exam 2 – mccord – (50970) 1 This print-out should have 34 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. McCord CH301 001 10.0 points Draw the Lewis structure For CO. 1. b b b b b b O b b b b C 2. b b b b b b O b b b b b b O C 3. O b b b b b b b b b b C 4. b b b b b b b b b b O C correct 5. O b b b b b b b b b b C 6. O b b b b b b b b C 7. b b b b b b b b O b b b b b b C 8. b b b b b b O b b b b b b C 9. b b b b b b O b b b b b b C 10. O 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 b b b b b b b b b b O C or b b b b O C This confguration gives each atom a com- plete octet. 002 10.0 points Which oF the Following has bond angles oF exactly 120 ? 1. HO 2 2. NO 2 3. O 3 4. CS 2 3 correct 5. S 2 3 Explanation: While CS 2 3 and NO 2 both have three re- gions oF electron density around the central atom, in NO 2 one oF these regions is a lone pair which will repel the other regions more strongly, making the bond angle less than 120 . Only in CS 2 3 would the bond angle be exactly 120 . 003 10.0 points Which oF the Following has the largest radius? 1. Cl 2. S 3. S 2 correct 4. Cl 5. K + Explanation: Although size decreases From leFt to right across the periodic table due to increasing e±ective nuclear charge, the negative ions will be the largest ions, and the negative ion with the largest charge will have the largest radius since the electrons will repel each other and the e±ective nuclear charge will be insu²cient to overcome this repulsion. 004 10.0 points Which oF the species NO, BrO, CH + 3 , 4 are radicals? 1. NO and BrO only correct
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Version 284 – Exam 2 – mccord – (50970) 2 2. NO and CH + 3 only 3. BrO and BF + 4 only 4. NO, CH + 3 and BF 4 only 5. NO and BF 4 only 6. BrO and CH + 3 only 7. BrO, CH + 3 and BF 4 only Explanation: The Lewis structures are N O b b b b b b b Br O b b b b b b b b b B F F F F b b b b b b b b b b b b b b b b b b b b b b b b H C H H + Radicals are species with an unpaired elec- tron, so only NO and BrO are radicals. 005 10.0 points Identify the compound with the most polar bond. 1. AsH 3 2. NH 3 correct 3. PH 3 4. SbH 3 Explanation: Calculate the di±erence in the electronega- tivities (ΔEN): ΔEN As H 2 . 2 - 2 . 2 = 0 . 0 N H 3 . 0 - 2 . 2 = 0 . 8 P H 2 . 2 - 2 . 2 = 0 . 0 Sb H 2 . 2 - 2 . 1 = 0 . 1 The N H bond is the most polar of these. 006 10.0 points What hybridization would you expect for the carbon atoms in the cyclic compound benzene (C 6 H 6 )? 1.
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EXAM2 - Version 284 Exam 2 mccord(50970 This print-out...

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