1.
Which one of the following Lewis structures is definitely incorrect?
A.
AlCl3       []
B.
SO32–     []2-
C.
COF2       []
D.
SF6       []
E.
XeF4       []


2.
Which one of the following Lewis structures is correct?
A.
AlCl3       []
B.
ClO4     []-
C.
COF2       []
D.
SOCl2       []
E.
XeF4       []


3.
For the chlorate ion, ClO3, select the most "important" resonance structure which contributes most to the resonance hybrid.
A.
[ ]-
B.
[ ]-
C.
[ ]-
D.
[ ]-
E.
[ ]-


4.
Which of the following atoms is most likely to violate the octet (or duplet) rule as a central atom in a molecule.
A.
H
B.
O
C.
P
D.
F
E.
none of the above


5.
Estimate the standard enthalpy, ΔH°, of the following reaction using the bond energy data provided.
        OF2(g)    +    H2O(g)    →   O2(g)   +   2HF(g)
Bond:
O-F
O-H
O=O
H-F
Bond energy (kJ/mol):
188
467
498
565
 
A.
346 kJ
B.
-346 kJ
C.
318 kJ
D.
-318 kJ
E.
455 kJ


6.
According to VSEPR theory, a molecule with the general formula AX3E2 will have a _____ molecular shape.
A.
trigonal bipyramidal
B.
T-shaped
C.
square planar
D.
trigonal pyramidal
E.
trigonal planar


7.
What is the molecular shape of the following ion as predicted by the VSEPR model?
        [ ]-
A.
trigonal planar
B.
tetrahedral
C.
trigonal pyramidal
D.
T-shaped
E.
V-shaped


8.
What is the molecular shape of SO3 as predicted by the VSEPR model?
A.
trigonal planar
B.
trigonal pyramidal
C.
tetrahedral
D.
T-shaped
E.
V-shaped


9.
What is the molecular shape of XeF2 as predicted by the VSEPR model?
A.
bent
B.
trigonal pyramidal
C.
V-shaped
D.
trigonal planarl
E.
linear


10.
Predict the bond angles in I3 by using the VSEPR model.
A.
60°
B.
90°
C.
120°
D.
180°
E.
109.5°


11.
Which one of the following molecules does not have a net dipole moment?
A.
SF6
B.
H2S
C.
CCl2I2
D.
PH3
E.
OF2


12.
What kind of hybrid orbitals are used for bonding in molecules with VSEPR formula AX2E2?
A.
sp hybrid orbitals
B.
sp3 hybrid orbitals
C.
sp2 hybrid orbitals
D.
sp3d2 hybrid orbitals
E.
sp3d hybrid orbitals


13.
The valence bond theory predicts that Br will use _____ hybrid orbitals in the molecule of BrF3.
A.
sp
B.
sp2
C.
sp3d
D.
sp3d2
E.
sp3


14.
The valence bond theory predicts that Br will use _____ hybrid orbitals in BrO3.
A.
sp
B.
sp2
C.
sp3d2
D.
sp3
E.
sp3d


15.
According to the valence bond theory, which of the following molecules involves sp2 hybridization of orbitals on the central atom(s) (shown in bold)?
A.
CH4
B.
H3CNH2
C.
H3CCH3
D.
HCCH
E.
H2CCH2


16.
According to the valence bond theory, how many sigma and how many pi bonds are present in the molecule of ethane, H3CCH3?
A.
7 σ and 0 π bonds
B.
6 σ and 1 π bonds
C.
7 σ and 1 π bonds
D.
6 σ and 0 π bonds
E.
5 σ and 2 π bonds


17.
According to the molecular orbital theory, what is the bond order in N2+?
A.
2
B.
2.5
C.
3
D.
1.5
E.
1


18.
According to the molecular orbital theory, which of the following statements about CO is correct?
A.
CO has a bond order of 1.5 and is paramagnetic.
B.
CO has a bond order of 1.5 and is diamagnetic.
C.
CO has a bond order of 2.5 and is paramagnetic.
D.
CO has a bond order of 2.5 and is diamagnetic.
E.
CO has a bond order of 3.5 and is paramagnetic.


19.
Which of the following statements relating to molecular orbital (MO) theory is correct?
A.
A bonding MO is higher in energy than the two atomic orbitals from which it is formed.
B.
A combination of two 2p orbitals always results in a sigma MO.
C.
A species with a bond order of zero will be stable only if it's diamagnetic.
D.
A combination of two atomic orbitals produces one bonding and one antibonding MO.
E.
All electrons must be paired in a stable molecule with even number of electrons.


20.
Which of the following statements is incorrect?
A.
Rotation around carbon-carbon double bonds is not allowed in molecules at normal conditions.
B.
Overlap of hybrid orbiatls leads to sigma-bond formation.
C.
The number of hybrid orbitals equals the number of atomic orbitals used in the hybridization.
D.
A carbon-carbon double bond in a molecule may give rise to cis and trans isomers.
E.
Hybridization is used in the molecular orbital theory in order to explain the proper bond orders in molecules.



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