CHE 105 - Mid-Term Examination III - 9 November 1995
University of Kentucky Department of Chemistry
1. The energy required to remove the highest-energy electron from a gaseous atom in its ground state is the
A. electronegativity. B. electron affinity. C. ionization energy. D. lattice energy.
2. Arrange the following in order of increasing first ionization energies. Ne, Na, Mg, Cl
A. Ne < Na < Mg < Cl B. Cl < Ne < Na < Mg C. Mg < Na < Cl < Ne D. Na < Mg < Cl < Ne
3. Which of the following are true statements?
1. The first ionization energy of all elements is greater than zero. 2. The electron affinity of all the elements is less than zero. 3. Fluorine is the most electronegative element.
A. 1 and 2 B. 1 and 3 C. 2 and 3 D. All three
4. Select the family of elements that is expected to have the highest electron affinities.
A. lanthanides B. alkali metals C. alkaline earths D. halogens
5. Which one of the following species has the largest number of unpaired electrons in the ground state?
A. Cr B. Cu+ C. Fe D. Mn
6. Calculate the enthalpy change for the reaction
N2H4(g) + O2(g) ---> N2(g) + 2 H2O(g)
based on the following bond energies:
N-N = 163 kJ N-H = 389 kJ O2 = 498 kJ N2 = 946 kJ H-O = 463 kJ
A. -433 kJ B. +345 kJ C. -581 kJ D. -1359 kJ
7. Arrange the following elements in order of increasing electronegativity N, O, P, Rb
A. N < O < P < Rb B. Rb < P < N < O C. O < N < P < Rb D. Rb < N < O < P
8. Which of the following species are paramagnetic?
1. O2 2. NO2 3. ClO 4. BF3 5. NH3
A. 3, 4, 5 B. 2, 3, 4 C. 1, 2, 3 D. 3, 4, 5
9. Which one of the following reactions is associated with the definition of the the lattice energy of MgI2?
A. MgI2(aq) ---> Mg2+(aq) + 2 I-(aq) B. MgI2(aq) ---> Mg2+(g) + 2 I-(g) C. MgI2(s) ---> Mg2+(g) + 2 I-(g) D. MgI2(g) ---> Mg2+(g) + 2 I-(g)
10. Arrange the following in order of increasing lattice energy.
LiF NaCl MgF2
A. NaCl < LiF < MgF2 B. MgF2 < LiF < NaCl C. LiF < NaCl < MgF2 D. NaCl < MgF2 < LiF
11. Consider the following Lewis structure
A. 0, 0, 0 B. 0, +1, -1 C. +1, 0, -1 D. -1, +1, 0
12. Select an appropriate Lewis structure for BrNO, and note the more polar bond in the molecule.
13. The most likely arrangement (connectivity) for the molecule H2CO is:
14. Which of the following molecules do not satisfy the octet rule?
NO2, H2O, IF3, C2H2
A. NO2 and H2O B. H2O and C2H2 C. IF3 and C2H2 D. NO2 and IF3
15. Determine the number of covalent bonds (CB), and the number of lone pairs (LP) in N2O4, assuming all atoms achieve a noble gas configuration.
A. CB = 14, LP = 40 B. CB = 7, LP = 20 C. CB = 14, LP = 20 D. CB = 7, LP = 10
16. What is the molecular geometry of PF3?
A. trigonal planar B. trigonal pyramidal C. tetrahedral D. T-shaped
17. According to the VSEPR theory, the expected geometry of the complex ion, ICl4-, would be:
A. tetrahedral B. square planar C. square pyramidal D. octahedral
18. Indicate the expected bond angle in NO2-.
A. 90o B. 109o28' C. 180o D. 120o
19. Select the molecule that has no molecular dipole moment.
A. CH4 B. CH3Cl C. CH2Cl2 D. CHCl3
20. Which of the following molecules are polar?
BH3, PCl5, H2O, NH3
A. H2O and NH3 B. BH3 and NH3 C. PCl5 and BH3 D. PCl5 and H2O
21. Formic acid, HCOOH, can be considered as the simplest organic carboxylic acid. What is the hybridization about the central carbon atom if the Lewis structure of the molecule can be written as
A. sp B. s2p C. sp2 D. sp3
22. The hybridization schemes used by the carbon atoms in
CH3-C=-C-CH2-OH
are
A. sp3, sp B. sp, sp2, sp3 C. sp, sp2 D. sp2, sp3
23. Acetylene, C2H2, contains
A. 1 sigma bond and 1 pi bond B. 3 sigma bonds and 2 pi bonds C. 3 sigma bonds and 1 pi bond D. 2 sigma bonds and 3 pi bonds
24. The bond orders of H2, H, He, and He2, in that order, are
A. 1, -1/2, -1/2, 0 B. 1, 1/2, 1/2, 0 C. 1, 1/2, 0, 0 D. 1, 0, 0, 0
25. What is the electron configuration and bond order of C2+?
