Chem 162-2011 some Chapter 19 practice problems(3)

Chem 162-2011 some Chapter 19 practice problems(3) - 21...

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CHAPTERS 19, 20, 21 CHEM 162-2007 POST-EXAM III PRACTICE PROBLEMS CHAPTER 19 - THE NUCLEUS RADIOACTIVE DECAY PARTICLES AND RAYS RADIOACTIVE DECAY KINETICS NUCLEAR BINDING ENERGY MISCELLANEOUS CHAPTER 18 - THE NUCLEUS RADIOACTIVE DECAY PARTICLES AND RAYS 9 Chem 162-2007 Final exam + answers Chapter 19 – The Nucleus Radioactive decay particles and rays When the Pd-106 nucleus is struck with an alpha particle, a proton is produced along with a new element. What is this new element? A. Cd-112 B. Cd 109 C. Ag-108 D . Ag-109 E. Ag-110 106 46 Pd + 4 2 α → 1 1 H + ? 106 46 Pd + 4 2 α → 1 1 H + 109 47 ? 106 46 Pd + 4 2 α → 1 1 H + 109 47 Ag 1
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13 Chem 162-2007 Final exam + answers Chapter 19 – The Nucleus Radioactive decay particles and rays What mode of radioactive decay is most likely for the isotope 11 20 Na? A. alpha emission B. beta emission C. gamma emission D . positron emission E. no decay: it’s a stable isotope Stable low atomic number atoms have a 1:1 ratio of neutrons to protons. As the atomic number increases, the ratio of neutrons to protons becomes slightly greater than 1:1. 20 11 Na contains 9 neutrons and 11 protons. Hence, the neutron to proton ratio is <1:1, so it is unstable. It needs more neutrons or less protons. A. 20 11 Na → 16 9 Na + 4 2 α This makes the ratio of neutrons to protons 7 to 9, which is going in the wrong direction. B. 20 11 Na → 20 12 Na + 0 -1 e This makes the ratio of neutrons to protons 8 to 12, which is going in the wrong direction. C. 20 11 Na → 20 11 Na + 0 0 γ This doesn’t do anything regarding fixing the ratio of neutrons to protons. D. 20 11 Na → 20 10 Na + 0 +1 e This makes the ratio of neutrons to protons 10 to 10 (i.e., 1:1) which is going in the correct direction. E. Stable low atomic number atoms have a 1:1 ratio of neutrons to protons. As the atomic number increases, the ratio of neutrons to protons becomes slightly greater than 1:1. 20 11 Na contains 9 neutrons and 11 protons. Hence, it is unstable. It needs more neutrons or less protons. 2
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Chem 162-2007 Final exam + answers Chapter 19 – The Nucleus Radioactive decay particles and rays When the U-235 nucleus absorbs a thermal neutron, Ba-141 and Kr-92 nuclei are produced along with some neutrons. How many neutrons are emitted? A. 2 B . 3 C. 4 D. 5 E. 6 235 92 U + 1 0 n → 141 56 Ba + 92 36 Kr + 3 0 ? 235 92 U + 1 0 n → 141 56 Ba + 92 36 Kr + 3 1 0 n 32 CHEM 162-2006 FINAL EXAM + ANSWERS CHAPTER 18 – THE NUCLEUS RADIOACTIVE DECAY PARTICLES AND RAYS An isotope with a high neutron to proton (N/Z) ratio will tend to decay through A. β-decay B. α-decay C. γ-decay D. electron capture E. positron emission An isotope with a high neutron to proton ratio will tend to form a stable nuclide by decreasing the neutrons or increasing the protons. Losing an electron (β-decay) will do this.
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This document was uploaded on 11/02/2011 for the course GEN CHEM 162 at Rutgers.

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Chem 162-2011 some Chapter 19 practice problems(3) - 21...

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