CHM 2045
Test 2
Form C
𝜇 =𝑞∙𝑟
%ionic character =
mmeasured
· 100%
mif 100%ionic
1 Debye = 3.34 x 10−30 Cm
Scoring: Six points each for questions 1 through 23; two points each for questions 24 through 32.
Directions: On the scantron bubble in your last name, first initial, section number, U-number
and Form C.
1
CHM 2045
Test 2
2
Form C
CHM 2045
Test 2
Form C
1. Draw the best Lewis structure for SO32-. How many equivalent resonance structures can be
drawn?
A. 1
B. 2
C. 4
D. 3
E. 8
2. What is the bond order for the NO bond in NO3-?
O
N
O
A. -1
B. 1
O
O
N
N
O
O
O
C. 1.33
O
D. 2
O
E. 4
3. HCl molecules have the dipole moment of   1.08D . The percent ionic character of H-Cl
bond is 20%. Estimate the bond length of H-Cl bond. The charge of one electron is 1.610-19 C.
A. 113 nm
B. 130 pm
C. 206 pm
D. 113 pm
E. 130 nm
4. Given the molecular orbital diagram below, determine the bond order for nitrogen gas, N2
A. 0
B. 1
C. 2
D. 3
3
E. 4
CHM 2045
Test 2
Form C
5. Which of the following is the best Lewis structure for ClF4+? Answer:C
6. Determine the Electron Geometry and Molecular Geometry of XeF4.
Electron Geometry
Molecular Geometry
A.
Linear
Linear
B.
Tetrahedral
Tetrahedral
C.
Tetrahedral
Bent
D. Trigonal Bipyramidal
Tetrahedral
E.
Octahedral
Square Planar
7. Determine the percent yield of a reaction that produces 28.65 g of Fe when 50.00 g of Fe2O3
react with excess Al according to the following reaction. (Molar masses: Fe = 55.85 g/mol, O =
16.00 g/mol, Fe2O3 = 159.70 g/mol)
Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s)
A. 61.03 %
B. 28.65 %
C. 57.30 %
D. 20.02 %
E. 81.93 %
8. Which of the following statements is TRUE?
A. A covalent bond is formed through the transfer of electrons from one atom to another.
B. A pair of electrons involved in a covalent bond are sometimes referred to as "lone pairs."
C. It is not possible for two atoms to share more than two electrons.
D. Single bonds are shorter than double bonds.
E. A covalent bond has a lower potential energy than the two separate atoms.
9. How many moles are in 25 mg of O2? (Molar mass O = 16.00 g/mol)
A. 7.8 ×10−4
B. 1.6 ×10−3
C. 0.40
D. 0.80
4
E. 800
CHM 2045
Test 2
Form C
10. Consider the reaction: 2 NO(g) + 5 H2(g)  2 NH3(g) + 2 H2O(g)
A reaction mixture initially contains 5 moles of NO and 10 moles of H2. Which set of amounts
best represents the mixture after the reactants have reacted as completely as possible.
A. 1 mol NO, 0 mol H2, 4 mol NH3, 4 mol H2O
B. 0 mol NO, 0 mol H2, 4 mol NH3, 4 mol H2O
C. 3 mol NO, 5 mol H2, 2 mol NH3, 2 mol H2O
D. 0 mol NO, 1 mol H2, 5 mol NH3, 5 mol H2O
E. 3 mol NO, 0 mol H2, 4 mol NH3, 2 mol H2O
11. What is the correct relationship between bond order, bond strength, and bond length?
A. As bond order increases, bond strength increases and bond length increases
B. As bond order increases, bond strength increases and bond length decreases
C. As bond order increases, bond strength decreases and bond length increases
D. As bond order increases, bond strength decreases and bond length decreases
12. Place the following in order of increasing A-Se-A bond angle, where A represents the outer
atoms in each molecule.
Cl
Cl
F
Se
F
Cl
O
Se
Cl
Se
O
Cl
Cl
A.
B.
C.
D.
E.
SeCl6 < SeF2 < SeO2
SeF2 < SeO2 < SeCl6
SeF2 < SeCl6 < SeO2
SeO2 < SeF2 < SeCl6
SeCl6 < SeO2 < SeF2
13. Give the hybridization for the O in OCl2, assume that O is the central atom.
A. sp
B. sp2
C. sp3
D. sp3d
E. sp3d2
5
CHM 2045
Test 2
Form C
14. Which compound has the highest carbon-carbon bond strength?
A. CH3CH3
B. CH2CH2
C. HCCH
D. all bond strengths are the same
15. Which of the following describes sp2 hybridzation?
A. Three orbitals are hybridized, one p-orbital remains unhybridized
B. Three orbitals are hybridized, one s-orbital remains unhybridized
C. Three orbitals are hybridized, no orbitals remain unhybridized
D. Four orbitals are hybridized, no orbitals remain unhybridized
E. Four orbitals are hybridized, one s-orbital remains unhybridized
16. Draw the Lewis structure for the molecule CH2CHCH3. How many sigma and pi bonds does
it contain?
A. 8 σ, 1 π
B. 9 σ, 0 π
C. 9 σ, 1 π
D. 7 σ, 2 π
E. 8 σ, 2 π
17. Which of the following describes the carbon in the best Lewis structure for HCN?
A. Carbon has two double bonds
B. Carbon has two single bonds and two lone pairs
C. Carbon has a single bond and a triple bond
D. Carbon has one single bond, one double bond, and one lone pair
E. Carbon has one single bond and three lone pairs
18. Which of the following describes the molecular geometry and polarity for XeO3?
A. Trigonal planar and non-polar
B. Trigonal planar and polar
C. Trigonal pyramidal and non-polar
D. Trigonal pyramidal and polar
E. T-shape and polar
6
CHM 2045
Test 2
Form C
19. Identify the compound with the highest percent ionic character.
A. HF
B. HCl
C. IBr
D. HI
E. LiF
20. In the chemical reaction N2 + 3 Mg  Mg3N2 if you begin with 1.35 moles of Mg, how
many moles of N2 are required to react all of the Mg?
A. 0.45
B. 1.01
C. 1.35
D. 1.80
E. 4.05
21. Consider the Lewis structure for formic acid (CO2H2). Determine the hybridization of the
carbon atom. Then determine the total number of sigma (σ) and pi (π) bonds in the molecule.
A.
B.
C.
D.
E.
Carbon hybridization= sp3, 3 σ bonds; 2 π bonds
Carbon hybridization= sp3, 4 σ bonds; 1 π bond
Carbon hybridization= sp2, 4 σ bonds; 1 π bond
Carbon hybridization= sp2, 3 σ bonds; 1 π bond
Carbon hybridization= sp2, 3 σ bonds; 2 π bonds
22. How many of the following statements about molecular orbital theory are true:
 Bonding orbitals are lower energy than atomic orbitals
 Non-bonding orbitals arrive from destructive interference of atomic orbitals
 Molecular orbitals arrive from a linear combination of atomic orbitals
 Filling molecular orbitals follows Hund’s rule
A. none
B. one
C. two
D. three
7
E. four
CHM 2045
Test 2
Form C
23. For the following four bonds (1) Br−Br, (2) C−S, (3) C−N, and (4) K−F, which statement is
true?
A. Two of them are polar covalent bonds
B. Two of them are pure (non-polar) covalent bonds
C. There is no ionic bond.
D. Only Br−Br bond is pure (non-polar) covalent
E. None of the above is true.
Consider a molecule of PCl5. For questions 25-34, indicate whether each statement is true (A) or
false (B) regarding PCl5.
24. The bond between P and Cl is polar
25. PCl5 is phosphorus pentachloride
26. When the preferred Lewis structure is drawn, no lone pairs appear on P
27. Cl has higher first ionization energy than P
28. Its electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2
29. Cl has a larger atomic radius than P
30. The molecule has sp3 hybridization
31. PCl5 is a polar molecule
32. Its molecular geometry is trigonal bipyramidal
8