PRINCE GEORGE’S COMMUNITY COLLEGE
CHM1010 (SHAH)
EXAM 3 (100 points)
Part I Multiple choices: Select the best answer and circle it.
1)
(40 points)
Identify the number of bonding pairs and lone pairs of electrons in water.
A) 1 bonding pair and 1 lone pair
B) 1 bonding pair and 2 lone pairs
C) 2 bonding pairs and 2 lone pairs
D) 2 bonding pairs and 1 lone pair
E) 3 bonding pairs and 2 lone pair
2)
Which of the following statements is TRUE?
A) An ionic bond is much stronger than most covalent bonds.
B) An ionic bond is formed through the sharing of electrons.
C) Ionic compounds at room temperature typically conduct electricity.
D) Once dissolved in water, ionic compounds rarely conduct electricity.
E) None of the above are true.
3) Which of the following represent the Lewis structure for Ca2⁺ ?
A)
B)
C)
D)
E)
4) Which of the following represent the Lewis structure for S2⁻ ?
A)
B)
C)
D)
E)
5) Use Lewis theory to determine the chemical formula for the compound formed
between Ca and N.
A) CaN B) Ca3N2
C) CaN2
D) Ca2N
E) Ca2N3
6) Place the following elements in order of increasing electronegativity.
K
Cs
A) P < K < Cs
P
B) K < P < Cs
C) Cs < P < K
D) Cs < K < P
7) Determine the electron geometry (eg) and molecular geometry (mg) of NCl 3.
A) eg=tetrahedral, mg=tetrahedral
B) eg=linear, mg=trigonal planar
C) eg=trigonal planar, mg=bent
D) eg=linear, mg=linear
E) eg=tetrahedral, mg=trigonal pyramidal
8) Determine the electron geometry (eg) and molecular geometry (mg) of BrF3.
A) eg=trigonal planar, mg=trigonal planar
B) eg=trigonal bipyramidal, mg= T-shape
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C) eg=trigonal planar, mg=bent
D) eg=trigonal bipyramidal, mg=see-saw
E) eg=tetrahedral, mg=trigonal pyramidal
9) Determine the electron geometry (eg) and molecular geometry (mg) of ICl 2⁻ .
A) eg=tetrahedral, mg=bent
B) eg=tetrahedral, mg=trigonal pyramidal
C) eg=trigonal bipyramidal, mg=linear
D) eg=trigonal bipyramidal, mg=trigonal planar
E) eg=octahedral, mg=linear
10) How many of the following molecules are polar?
BrCl3
A) 1
CS2
B) 2
SiF4
C) 3
D) 4
SO3
E) 0
11) Determine the electron geometry, molecular geometry and polarity of N 2O (N central).
A) eg=linear, mg=linear, nonpolar
B) eg=tetrahedral, mg=linear, nonpolar
C) eg=tetrahedral, mg=bent, polar
D) eg= linear, mg=linear, polar
E) eg=trigonal planar, mg=bent, polar
12) A molecule containing a central atom with sp3d hybridization has a(n) electron
geometry.
A) tetrahedral
B) linear
C) octahedral
D) trigonal planar
E) trigonal bipyramidal
13) Draw the Lewis structure for OF2. What is the hybridization on the O atom?
A) sp B) sp3 C) sp2 D) sp3d
E) sp3d2
14) Draw the Lewis structure for the molecule CH2CHCH3. How many sigma and pi bonds
does it contain?
A) 8 sigma, 1 pi
B) 9 sigma, 0 pi
C) 9 sigma, 1 pi
D) 7 sigma, 2 pi
E) 8 sigma, 2 pi
15) What is the strongest type of intermolecular force present in CHF 3?
A) ion-dipole B) dispersion C) hydrogen bonding D) dipole-dipole
16) What is the strongest type of intermolecular force present in NH2CH3?
A) dispersion B) dipole-dipole
C) hydrogen bonding
D) ion-dipole
17) Place the following compounds in order of decreasing strength of intermolecular
forces.
HF
O2
CO2
2
A) HF > CO2 > O2
B) HF > O2 > CO2
C) O2 > CO2 > HF
D) CO2 > HF > O2
18) Identify the compound that does not have hydrogen bonding.
A) (CH3)3N
B) H2O
C) CH3OH
D) HF
E) CH3NH2
19) Which of the following compounds exhibits only dispersion and dipole-dipole
intermolecular interactions?
A) H2
B) HI
C) CO2
D) CH3NH2
20)
Which of the following statement is true?
A)
B)
C)
D)
E)
Electronegativity generally increases across a period in the periodic table.
Fluorine is the most electronegative element in halogen group.
The greater electronegative difference, more polar the bond is.
All of the above
None of the above
Part II Problems solving (60 points)
1. Explain an appropriate chemical bond in each of the following
compounds/molecules. (10)
MgO
NCl3
SbCl3,
GaH3
2. Write EG, MG, bond angle, Polar or Nonpolar, hybridization, number of sigma bonds,
and number of pi bonds around central atom in the following molecules or ions.
(20 points)
a. SeO2
b. SbF5
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c. NO2-
d. C3H7OH
e. CH3O2
3. Draw the Lewis structures and calculate the formal charges for each atom. (10)
a. CO
b. SeOCl2
c. CH3CNO
d. ICl3
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4. Draw the possible Lewis structure and if they contain resonance forms, write all
resonance structures. (5)
a. NO2-
b. H2CS
b. Identify intermolecular forces in the following: (5)
a.
b.
c.
d.
e.
5.
a.
b.
c.
d.
e.
Ne
PCl3
BF3
XeF4
H2S
True or False (10)
O2 molecule is nonpolar but O3 molecule is polar.
The orbital overlap side by side between two p orbitals forms a pi bond.
Generally Pi bond is weaker than sigma bond in double bond.
Double bond is stronger than single bond but shorter than single bond.
PH3 molecules contains three hydrogen bonds and water contains only two
hydrogen bonds.
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