Homework 4-solutions - el56 Homework 4 Walker (53970) 1...

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Unformatted text preview: el56 Homework 4 Walker (53970) 1 This print-out should have 37 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 1.0 points How many lone electron pairs are found on the central atom of SCl 4 ? 1. 2 2. 5 3. 1 correct 4. 3 5. 4 Explanation: 002 1.0 points (Note from your instructor: MgCl2 is not the answer to this question.) Which of the following compounds I) CH 4 II) PCl 5 III) XeF 2 IV) MgCl 2 are exceptions to the octet rule? 1. II and III correct 2. II, III and IV 3. IV only 4. III only 5. III and IV Explanation: MgCl 2 is ionic. C H H H H satisfies the octet rule. Both P in P Cl Cl Cl Cl Cl and Xe in Xe F F have 10 valence e- , thus vio- lating the octet rule. 003 1.0 points A hydrogen atom does not bond to more than one element at a time because 1. Hydrogen prefers to exist as a homonu- clear diatomic molecule. 2. It is too small. 3. Hydrogen prefers to exist as a free radi- cal. 4. It doesnt form covalent bonds. 5. With only two electrons needed to fill its valence shell it cant. correct Explanation: 004 1.0 points Which of the following is the correct Lewis formula for boron trifluoride (BF 3 )? 1. b b b b b b b b b b b b b b b b b b b b F B F F 2. b b b b b b b b b b b b b b F B F F 3. b b b b b b b b b b b b b b b b b b b b b b b b F B F F correct 4. F b b B b b b b F b b b b b b F el56 Homework 4 Walker (53970) 2 5. b b b b b b b b b b b b b b b b b b b b b b b b b b F B F F 6. b b b b b b b b b b b b b b b b b b F B F F 7. b b b b b b b b b b b b F B F F 8. b b b b b b b b b b F B F F 9. F B F F b b b b b b b b b b b b b b b b b b 10. F b b b b b b b b B b b b b F b b b b b b F b b b b b b Explanation: The Lewis formula for boron trifluoride (BF 3 ) is b b b b b b b b b b b b b b b b b b b b b b b b F B F F 005 1.0 points The energy of a photon of light 1. is highest for red light. 2. increases with increasing frequency. cor- rect 3. None of the other choices is correct. 4. increases with increasing wavelengths. Explanation: For a photon E = h where h is a constant, E is energy and is frequency. E and are directly proportional. If E increases, increases since h is a constant. 006 1.0 points What is the wavelength of radiation of fre- quency 4 . 80 10 13 s- 1 ? 1. 6 . 25 10- 6 m correct 2. 1 . 60 10 1 m 3. 7 . 10 10- 7 m 4. 1 . 44 10 22 m 5. 3 . 48 10- 8 m Explanation: c = 3 10 8 m / s = 4 . 8 10 13 s- 1 c = = c = 3 10 8 m 1 s 1 s 4 . 8 10 13 = 6 . 25 10- 6 m 007 1.0 points (Note from your instructor: For this prob- lem, select the answer choice closest to your calculated answer.) What is the energy of a photon of light with a frequency of 6 . 10 14 s- 1 ?...
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This note was uploaded on 05/05/2008 for the course CH 304k taught by Professor Walker during the Spring '08 term at University of Texas at Austin.

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Homework 4-solutions - el56 Homework 4 Walker (53970) 1...

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