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Unformatted text preview: el56 Homework 3 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 The dominant source of ground level ozone in the U.S. is 1. volcanic emissions. 2. photochemical decomposition of NO 2 from automobile exhausts to produce O atoms that react with O 2 molecules. correct 3. lightning strikes. 4. the photochemical reactions of unburned hydrocarbons emitted from power plants us- ing fossil fuel sources. 5. transport from the stratosphere. Explanation: In the presence of sunlight, NO 2 NO + O O + O 2 O 3 002 1.0 points Protective ozone is in the (mesosphere, strato- sphere, troposphere), but ozone in the (meso- sphere, stratosphere, troposphere) is a pollu- tant. 1. mesosphere; stratosphere 2. stratosphere; mesosphere 3. stratosphere; troposphere correct 4. troposphere; stratosphere Explanation: 003 1.0 points Carbon has several isotopes, one of which, with a mass of 14 amu, is radioactive. This isotope has 1. 6 protons and 6 neutrons. 2. 6 protons and 7 neutrons. 3. 7 protons and 7 neutrons. 4. 6 protons and 8 neutrons. correct 5. 8 protons and 6 neutrons. Explanation: Carbon has an atomic number of 6 and therefore has 6 protons. If the atomic mass (the number of p + + the number of n ) is 14 amu then there are 14- 6 = 8 neutrons in 14 C. 004 1.0 points Which isotope has 35 protons, 35 electrons, and 46 neutrons? 1. 46 35 Br 2. 35 46 Pd 3. 81 46 Pd 4. 81 35 Br correct Explanation: The standard nuclide symbol takes the form of A Z E were E is the element symbol, A is the mass number (number p + + number n ), and Z is the atomic number (number p + ). An isotope with 35 protons ( p + ) and 46 neutrons ( n ) has an atomic number of 35 and a mass number of 35 p + + 46 n = 81 amu. Br has an atomic number of 35, so the isotope is 81 35 Br. 005 1.0 points How many neutrons are there in one atom of 48 22 Ti? 1. 70 2. 26 correct 3. 22 4. None of these el56 Homework 3 Walker (53970) 2 5. 48 Explanation: The standard nuclide symbol takes the form A Z E, where E is the element symbol, A is the mass number (number of n + number of p + ) and Z is the atomic number (number of p + ). The atomic number for 48 22 Ti is 22, and its mass number is 48. 48 = p + + n = 22 + n n = 48- 22 = 26 neutrons 006 1.0 points The atomic number, which orders the ele- ments in the periodic table, has been identi- fied as ? of the atom. 1. the number of electrons in the nucleus 2. the sum of the number of protons and neutrons in the nucleus 3. the number of neutrons in the nucleus 4. the number of protons in the nucleus correct Explanation: The atomic number defines the atom and refers to the number of protons in the atom....
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- Spring '08