Midterm 2 Fall Page 1

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Russell Sanders
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1 1. Three of the molecular shapes which a sp3d hybridized molecule can have are: A. triangular, trigonal bipyramid, linear B. linear, square planar, T-shaped C. irregular tetrahedron, T-shaped, bent D. T-shaped, linear, trigonal bipyramid E. none of these is correct 2. Which of the following must be paramagnetic? A. F2 B. N2 C. SO2 + D. H2 E. ClO2-3. In a plutonium bomb such as the one used over Nagasaki, the nuclear explosion occurs when A. two masses of fissionable material are placed against each other. B. the fissionable material is compressed with conventional explosives. C. a fission reaction triggers the chain reaction. D. a source of protons is injected in the fissionable material so as to achieve critical mass. E. critical mass is achieved by compressing two masses of tritium against each other with conventional explosives. 4. According to the band theory, which of the following provide(s) an explanation for the high electrical conductivity of metals? 1. a partly filled conduction band 2. a valence band overlapping an empty conduction band 3. a filled valence band 4. a large gap between the valence band and the conduction band A. 1, 2 B. 1, 3 C. 3 D. 3, 4 E Which of the following was NOT a factor in the Chernobyl disaster? A. loss of coolant B. explosion of hydrogen C. hydrogen fusion reactions D. high pressure E. high temperatures Page 1

2 6. Which is the most paramagnetic species? A. Si B. Mg C. Ni D. Ag E. Nb 7. According to the M.O. theory the removal of an electron from the C2 molecule will have what effect? (pick the best answer) A. It will cause the bond order to increase and the ion will be diamagnetic B. It will cause the bond order to decrease and the ion will be diamagnetic. C. It will cause the bond order to increase and the ion will be paramagnetic. D. It will cause the bond order to decrease and the ion will be paramagnetic. E. It will cause the bond order to decrease but will have no effect on the magnetism. 8. List in order of increasing ionization potential: O, Mg, Rb, S, Si a) Si < S < Rb < Mg < O b) Mg < O < Rb < S < Si c) S < Si < Mg < O < Rb d) Rb < Mg < Si < S < O e) Si < O < Mg < Rb < S A. b B. d C. e D. d Page 2

3 9. Which represents the best distribution of electrons among orbitals for the central nitrogen atom in _ [ ] A. B. N N Ṅ. s p s p C. sp2 p D. sp p E. sp3 10. OMIT Which one of the following statements concerning ozone depletion is correct? A. Ozone depletion is mainly responsible for the observed increase in skin cancers in North America. B. CFCs are very stable molecules because of the presence of strong carbon-chlorine bonds. C. The mechanism of ozone depletion involves the formation of fluorine monoxide free radicals. D. In CFCs substitutes the fluorine atoms are replaced with hydrogen atoms. E. CFC's have been completed banned around the world since 1998 because of their ozone depleting effect. 11. Radium 226 decays by alpha emission. What is its decay product? A. 228 B. 87 Fr 222 C. 86 Rn 230 D. 90 Th 226 E. 89 Ac Page Po

4 12. With one of the following bond descriptions is correct? A. CsF Pure covalent B. F2 Ionic C. NAs Pure covalent D. HCl Polar covalent E. BrCl Ionic 13. Sulfur-35 decays by beta- emission. The decay product is A B. P S C. 31 D. 30 Si 34 E. 17 Cl Cl 14. According to the molecular orbital (M.O.) theory, when two oxygen atoms bond together, the p orbitals on each atom combine to form: A. two sigma M.O.'s and four pi M.O.'s B. two sigma M.O.'s and two pi M.O.'s C. four pi M.O.'s only D. one sigma and one pi M.O. E. none of the listed answer is correct 15. The sulfur atom, with a formal charge of zero in the resonance structure of SO3-2, has around it: A. three single bonds and one lone pair B. two double bonds, one single bond and a lone pair C. three double bonds and a lone pair D. one triple bond and a double bond E. two single bonds, one double bond and a lone pair 16. What is the bond order of O2 - according to the MO theory A. 1 B. 1/2 C. 3/2 D. 0 E What is the missing symbol in this plutonium fission reaction? Pu + n + Sr + 3 n 1 0 A. 148 B. 56 Ba -1 0 β C. 143 D. 54 Xe Sr E Ba Page 4

5 18. OMIT Which of the following statements concerning global warming is NOT correct? A. Nuclear power does not contribute significantly to global warming B. Past temperatures can be measured by taking ice core samples from the polar regions. C. In global warming, infrared radiation is prevented from escaping from the earth's atmosphere. D. The recently observed global temperature increases are much larger than any previous temperature variations. E. Global warming has always existed and has been beneficial to life on earth. 19. Calculate the nuclear binding energy per nucleon in joules for magnesium-25 (atomic mass amu) given the atomic masses of the proton ( amu) nd the neutron ( amu) A J/nucleon B J/nucleon C J/nucleon D J/nucleon E. None of the listed answers. 20. The concept of an anti-bonding orbital is unique to the: A. theory of bond hybridization B. valence bond theory C. molecular orbital theory D. concept of resonance E. electrostatic repulsion theory 21. What is the formal charge on B in BF4 -? A. 1 B. -1 C. 2 D. 0 E When Sr undergoes positron emission, the product nucleus is: A. 90 B. 37 Rb Sr C Y D Sr E. 89 Y 39 Page 5

6 23. What change in hybridization occurs around the sulfur in the following reaction SF 6 SF F - A. sp3 to sp2 B. sp3d2 to sp3 C. sp3d to sp3d2 D. sp3d2 to sp3d E. No change occurs in hybridization 24. Calculate the energy released in joules when one mole of Po 214 decays according to the equation Po 82 Pb He Given the atomic masses: Pb 210 = amu, Po 214 = amu, and He 4 = amu. A J/mol B J/mol C J/mol D J/mol E J/mol 25. OMIT Which one of the following statements concerning Linus Pauling is NOT correct? A. Linus Pauling received a Nobel Prize for Peace for his fight against nuclear testing in the atmosphere. B. He showed that the use of megadoses of Vitamin C can prevent the common cold. C. Linus Pauling originated the theory of the covalent bond. D. Linus Pauling's letter to Roosevelt led to the development of the atomic bomb. E. He developed a scale to measure the electronegativity of the elements 26. Which one of the following statements concerning radiation is correct? A. α (alpha) particles are the most dangerous form of radiation because they are the most penetrating. B. Radon-222 is especially dangerous because it gives off γ (gamma) radiation; C. In the case of the "Radium Girls", the observed cancers were caused by inhaled γ (gamma) particles. D. Iodine-127, because it has a very long half-life, is used in cancer treatment. E. In PET scans, γ (gamma) rays are recorded to detect brain activity. Page 6

7 27. Which one of the following molecules is non-polar? A. BCl3 B. H2O C. NCl3 D. PCl3 E. All are polar 28. In the band theory, why is a material such as diamond an insulator? A. All of the electrons are in the conduction band. B. All of the electrons are tied to nuclei. C. Very few electrons can make the transition over the large energy gap between the valence band and the conduction band. D. The bonds in diamond are too strong to allow atoms to move so no current flows. E. There are no electrons in the valence band. 29. Which compound would be expected to have the shortest carbon-carbon bond? A. H3CCH3 B. HCCH C. H2CCH2 D. F3CCF3 E. Cl2CCCl2 30. Which of the following elements when doped into silicon would create an n-type semiconductor? A. C B. Ga C. P D. Ge E. B 31. Which of the following electron transitions in the hydrogen atom results in absorption of light of the longest wavelength? A. n = 7 to n = 6 B. n= 5 to n = 6 C. n = 1 to n = 6 D. n = 4 to n = 3 E. n = 1 to n = The hybridization that agrees with the geometry around the central atom in the ion I 3 - is A. sp B. sp2 C. sp3 D. sp3d E. sp3d2 Page 7

8 33. The resonance structure of PO4-3 where the central atom carries a formal charge of zero is surrounded by A. 4 sigma bonds B. 4 sigma and 1 pi bonds C. 4 sigma and 2 pi bonds D. 4 sigma and 3 pi bonds E. 4 sigma and 4 pi bonds 34. Given the Lewis structures below indicate which is/are more plausible F : : F. F S F. F S F. : : F.. F S F N N. : :.... N. F : :. F S F. N A. 1 and 2 are more plausible B. 2 alone is more plausible C. 2 and 3 are more plausible D. 3 alone is more plausible E. 4 alone is more plausible 35. What would be the ionization energy for a hydrogen atom on another planet where a high surface temperature resulted in the fifth principle energy level being the ground state for hydrogen under these extraterrestrial conditions? A x10-20 J B x10-18 J C x10-19 J D x10-20 J E x10-19 J 36. The molecular geometry around the central atom in SF4 is A. tetrahedral B. square planar C. pyramidal D. T-shaped E. seesaw 37. Which of the following molecules have the same geometries? A. SF 4 and CH 4 B. CO 2 and H 2 O C. CO 2 and BeH 2 D. N 2 O (NNO) and NO 2 E. None of the above pairs have the same geometries Page 8

9 38. OMIT Which one of the following statements concerning aspects of chemistry is NOT correct? A. Acetone and ethanol are among the compounds naturally found in apples. B. Diamond is thermodynamically more stable than graphite C. The colour of gemstones is caused by the presence of trace metals. D. The name rubber was coined by Joseph Priestley, the man who discovered oxygen. E. Nitrous oxide was once used as a recreational drug at parties called "frolics". 39. Predict the geometry and polarity of the CS 2 molecule. A. linear, polar B. linear, nonpolar C. tetrahedral, nonpolar D. bent, nonpolar E. bent, polar 40. The carbon 14 activity of some ancient Indian corn was found to be 7.0 disintegrations per minute (dpm) per gram of carbon. If present-day plant life has 16 dpm per gram of carbon, how old is the Indian corn? t 1/2 = 5,730 yr. A. 6,800 yr B. 2,500 yr C. 4,700 yr D. 10,000 yr E. 7,200 yr 41. The half-life of 14C is 5600 years. If a specimen of charcoal contains 3.78 disintegrations/min per gram of carbon, how old is the sample? When formed, carbon contains 15.1 disintegrations/min per gram. A. 7,900 years B. 1,400 years C. 18,350 years D. 5,600 years E. 11,200 years 42. What is the molecular shape of BrF5? A. linear B. square pyramid C. square planar D. octahedral E. trigonal bipyramid Page 9

10 Answer Key No. on Test 1 D 2 C 3 E 4 A 5 C 6 E 7 D 8 D 9 D 10 B 11 B 12 D 13 E 14 B 15 E 16 C 17 E 18 D 19 C 20 C 21 B 22 A 23 D 24 C 25 B 26 E 27 A 28 C 29 B 30 C 31 B 32 D 33 B 34 E 35 D 36 E 37 C 38? 39 B 40 A 41 E Correct Answer Page 10

11 42 B Page 11

Practice Final # Jim and Tim s Excellent Adventure s in Final Exam Preparation. Practice Final

Practice Final # Jim and Tim s Excellent Adventure s in Final Exam Preparation. Practice Final Jim and Tim s Excellent Adventure s in Final Exam Preparation Practice Final 1 2013 1. What type of orbital is designated by the quantum numbers n = 3, l = 1, and m l = 0? A. 4p B. 1f C. 3s D. 3p E. 3d