CHEMISTRY 110 EXAM 1 Sept. 24, 2012 FORM A 1. A microwave oven uses 2.45! 10 9 Hz electromagnetic waves to heat food. What is the wavelength of this radiation in mm? A. It is impossible to tell from the information given. B. 294 mm C. 122 mm D. 10 mm E. 60 mm 2. Identify the total number of electrons in a ground state Mg 2+ ion that reside in orbitals of spherical shape such as the figure shown below. A. 4 B. 6 C. 8 D. 10 E. 12 3. What is the total number of valence electrons present in PO 4 3"? A. 24 B. 27 C. 30 D. 32 E. 33 4. Which of the following species has the same number of electrons and neutrons? A. 1 H B. C. 40 Ca 2+ 14 C D. 19 F " E. 14 C 2+ 5. What is the correct order of the following elements listed in increasing atomic radius. Na, Mg, K, A. Na < Mg < K < Rb B. Mg < Na < K < Rb C. Rb < K < Mg < Na D. Rb < Mg < K < Na E. Rb < K < Na < Mg Rb
6. Which of the following electromagnetic waves are ranked correctly in terms of smallest to largest wavelength. A. x-rays < microwaves < visible light < infrared radiation B. visible light < x-rays < infrared radiation < microwaves C. infrared radiation < x-rays < visible light < microwaves D. microwaves < visible light < x-rays < infrared radiation E. x-rays < visible light < infrared radiation < microwaves 7. Which set of quantum numbers could describe the unpaired electron in the ground state of Cl? A. n = 2,! = 1, m! =1, m s = 1 B. n = 2,! = 2, m! =1, m s = "# C. n = 3,! = 1, m! = 1, m s = "1 D. n = 3,! = 1, m! = "1, m s = "# E. n = 3,! = 2, m! = +1, m s = # 8. What is the overall change in internal energy for System A after both of the following processes have occurred? Process 1: System A absorbs 10 kj of heat from the surroundings and does 8 kj of work on its surroundings. Process 2: System A releases 5 kj of heat into the surroundings and 10000 J of work is done on the system. A. 2 kj, $E = negative B. 7 kj, $E = positive C. 33 kj, $E = negative D. 9982 J, $E = positive E. 3000 J, $E = negative 9. According to Bohr s Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon? A. n=5 to n=3 B. n=6 to n=1 C. n=4 to n=3 D. n=5 to n=4 E. n=6 to n=5
10. Which graph best shows the relationship between the energy of a photon (E photon ) and its wavelength (!). The arrows in the graphs denote the direction of increasing photon energy and wavelengths of increasing length. 12. Which of the following orbitals could have the quantum number n=3, m! =1? I II III IV V A. II only B. I and III C. IV and V only D. I, III, IV and V E. all of them 13. Arrange the ions within the isoelectronic series in order of decreasing radius. 11. How many unpaired electrons are present in a ground state Cu + ion? A. 0 B. 1 C. 2 D. 3 E. 4 Mg 2+ Al 3+ Na + F A. Na + > Mg 2+ > Al 3+ > F B. Al 3+ > Mg 2+ > Na + > F C. F > Na + > Mg 2+ > Al 3+ D. F > Al 3+ > Mg 2+ > Na + E. The atoms or ions in this series are not isoelectronic. Go on to the next page
14. Which of the following statements is false? 16. Which of the following is the best Lewis dot structure for NO 2? A. K +, Ca 2+, S 2, and Cl are isoelectronic. B. Fluorine is more electronegative than Cl. C. When a metal forms a cation, it loses electrons. D. K + < Cl < S 2 are listed in order of increasing radius. E. The ground state electronic configuration of Cr 3+ ion is [Ar]4s 1 5d 2. 15. Which of the following is an incorrect Lewis structure for the most stable state of the molecule or ion shown? A. B. C. D. E. A. C O B. O S C. C N O O D. E. C C Cl Cl H O H - 17. Which of these molecules has a stable structure that violates the octet rule? i. BH 3 ii. NO iii. XeF 2 A. ii only B. iii only C. i and ii D. i and iii E. all three Go on to the next page
18. Which of the following molecules possesses the most number of equivalent resonance structures? A. SO 3 2" B. NO 2 C. CH 4 D. CO 2 E. SO 2 19. Which of the following samples contains the largest number of total atoms? A. 0.5 mole of ethane (C 2 H 6 ) B. 6.02! 10 23 molecules of HF C. 56.8 grams of P 2 O 5 D. 0.5 mole of water (H 2 O) E. 1.5! 10 24 atoms of argon (Ar) 20. Identify the atom by the following excited-state configuration: 1s 2 2s 2 2p 6 3s 2 3d 5 A. Fe B. Sn C. Cl D. Al E. None of the above 21. Put these in order of increasing electronegativity. Ca Si O Al Ba A. Ba <Ca < Al < Si < O B. Ca <Ba < Si< Al < O C. O < Al < Si < Ca < Ba D. Al < Ca < Ba < Si < O E. Ba < Ca < O < Al < Si 22. The following ionization energies were obtained for successive ionizations of an atom in the second period of the Periodic Table. Identify the atom. M(g) " M + (g) + e M + (g) " M 2+ (g) + e M 2+ (g) " M 3+ (g) + e M 3+ (g) " M 4+ (g) + e A. Li B. Be C. B D. C E. N Ionization Energy 800 kj/mol 2,427 kj/mol 3,660 kj/mol 25,026 kj/mol Go on to the last page
23. A single photon of light with a wavelength of 250 nm strikes a material and is completely absorbed. The material then emits a photon with a wavelength of 605 nm. What is the net change in energy of the material? A. 7.96! 10 "19 J B. 3.29! 10 "19 J C. +1.12! 10 "18 J D. +4.67! 10 "19 J E. 5.62! 10 "19 J 24. Lithium forms compounds that are used in storage batteries and hightemperature lubricants. It has two naturally occurring isotopes, 6 Li (atomic mass = 6.015 amu) and 7 Li (atomic mass = 7.016 amu). What is the percent abundance of 6 Li? A. 92.50% B. 86.66% C. 46.16% D. 7.493% E. 6.080% -------------------------------------------------------------------------------------- 25. A dye laser emits a pulse that contains 2.75! 10 15 photons. The wavelength of the pulse is shown below. What is the total energy of this pulse? A. 4.3! 10 "19 J B. 1.4! 10 2 J C. 3.9! 10 "5 J D. 2.5! 10 5 J E. 1.2! 10 "3 J 450 nm 26. Draw Lewis structures for NO 2 +, NO 2 " and NO 3 ". Based on the interpretation of the Lewis structures, put these in order of increasing bond order. A. NO 2 + < NO 2 " < NO 3 " B. NO 2 + < NO 3 " < NO 2 " C. NO 2 " < NO 3 " < NO 2 + D. NO 3 " < NO 2 " < NO 2 + E. NO 2 " < NO 2 + < NO 3 "
27. Rank the following series of charges in order of increasing electrostatic energy. CHEMISTRY 110 EXAM 1 SEPTEMBER 24, 2012 Answer Key A. I = II < III B. I < II < III C. II < I < III D. III < II < I E. II < III < I 28. What is the value of n i for an electron that emits a photon of wavelength 95.04 nm when it returns to the ground state in the H atom? A. n i = 6 B. n i = 5 C. n i = 4 D. n i = 3 E. n i = 2 FORM A 1. C 2. A 3. D 4. D 5. B 6. E 7. D 8. B 9. E 10. C 11. A 12. D 13. C 14. E 15. D 16. B 17. E 18. A 19. A 20. C 21. A 22. C 23. D 24. D 25. E 26. D 27. C 28. B END OF EXAM