Exam 1 MWF-solutions

Exam 1 MWF-solutions - Version 131 – Exam 1 MWF –...

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Unformatted text preview: Version 131 – Exam 1 MWF – Sutcliffe – (50965) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points An electron in a hydrogen atom moves from the n = 2 to n = 5 level. What is the wave- length of the photon that corresponds to this transition and is the photon emitted or ab- sorbed during this process? 1. 276 nm; absorbed 2. 434 nm; absorbed correct 3. 434 nm; emitted 4. 1875 nm; emitted 5. 276 nm; emitted 6. 1875 nm; absorbed Explanation: 002 10.0 points As an atom’s radius increases, 1. its ionization energy decreases. correct 2. its ionization energy increases. 3. its ionization energy does not change. 4. its ionizations energy increases or de- creases depending on whether you are going up a column or across a row. Explanation: Ionization energy is the amount of energy required to remove the most loosely bound electron. As an atom’s radius increases, the outermost electrons are farther from the nu- cleus and do not feel the pull of the nuclear charge as strongly. Therefore, they are eas- ier to remove and the ionization energy is decreased. 003 10.0 points What is the lowest energy electron configura- tion of Cr? 1. 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 5 2. 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 6 4 s 2 3. 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 5 5 s 1 4. 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 6 5. None of these correct Explanation: 004 10.0 points How many kg are in 10.0 mg? 1. 1 . 00 × 10 − 3 kg 2. 1 . 00 × 10 − 7 kg 3. 1 . 00 × 10 − 4 kg 4. 1 . 00 × 10 − 6 kg 5. 1 . 00 × 10 − 5 kg correct Explanation: ? kg = 10 . 0 mg × 1 g 1000 mg × 1 kg 1000 g = 1 × 10 − 5 kg 005 10.0 points Which of the following is a chemical property of sulfur? 1. dissolves in carbon disulfide 2. melts at 119 ◦ C 3. density of 2.07 g/ml 4. burns in air correct Explanation: Burning in air as opposed to melting or dis- solving shows a change it undergoes in chem- ical composition. Melting and dissolving are physical properties not chemical. Version 131 – Exam 1 MWF – Sutcliffe – (50965) 2 006 10.0 points Which element is in the same group as phos- phorous? 1. oxygen 2. magnesium 3. nitrogen correct 4. carbon Explanation: Groups are the columns that run vertically down the periodic table. 007 10.0 points Which elements are correctly listed in order of INCREASING ionization energy? 1. N < O < F 2. N < P < As 3. O < S < Se 4. O < F < Ne correct 5. C < N < O Explanation: Ionization enegy corresponds to how much energy it takes to ionize an element. Elements with high ionization energies do not want to give up their electrons, low ionization energies mean they do not want to receive an electron, but would rather give one up. In general, ionization energies increase as you move right along a period and up a group. Some atoms (like B, O, Al and S) can achieve more stable electronic configuration in filled or half-filled shells....
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This note was uploaded on 03/09/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Exam 1 MWF-solutions - Version 131 – Exam 1 MWF –...

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