1.
Which one of the following Lewis structures is definitely incorrect?
1) NO2       2) BeCl2    3) CO32-    
4) CH4    5) SO2
A.
1
B.
2
C.
3
D.
4
E.
5


2.
Hydrazine, N2H4, is a good reducing agent that has been used as a component in rocket fuels. Select its Lewis structure.
1)    2)    3)    4)
A.
1
B.
2
C.
3
D.
4
E.
None of the above is correct.


3.
Select the Lewis structure in which formal charges are minimized for the periodate anion, IO4–.
1)    2)    3)    4)
A.
1
B.
2
C.
3
D.
4
E.
All have the same formal charges


4.
In which one of the following species is the central atom (the first atom in the formula) likely to violate the octet rule?
A.
NH4+
B.
XeO3
C.
CCl4
D.
NH3
E.
CH2Cl2


5.
Nitrogen and hydrogen combine to form ammonia in the Haber process. Calculate (in kJ) the standard enthalpy change ΔH° for the reaction written below, using the bond energies given.
N2(g)   +   3H2(g)   →   2NH3(g)
Bond:
N≡N
H–H
N–H
Bond energy (kJ/mol):
945
432
391
A.
-969 kJ
B.
-204 kJ
C.
-105 kJ
D.
204 kJ
E.
595 kJ


6.
According to VSEPR theory, a molecule with the general formula AX2E2 will have a _____ molecular shape.
A.
linear
B.
bent
C.
trigonal planar
D.
tetrahedral
E.
see-saw


7.
What is the molecular shape of the thiocyanate anion, SCN-, as predicted by the VSEPR theory? (Carbon is the central atom.)
A.
linear
B.
bent
C.
angular
D.
trigonal
E.
none of the above


8.
What is the molecular shape of NOCl as predicted by the VSEPR theory?
A.
linear
B.
trigonal planar
C.
bent
D.
tetrahedral
E.
trigonal pyramidal


9.
What is the molecular shape of ClF4– as predicted by the VSEPR theory?
A.
square pyramidal
B.
square planar
C.
see-saw
D.
octahedral
E.
tetrahedral


10.
Predict the ideal bond angles in IF2– using the molecular shape given by the VSEPR theory.
A.
60°
B.
90°
C.
109°
D.
120°
E.
180°


11.
Which one of the following molecules does not have a dipole moment?
A.
CS2
B.
H2S
C.
CH2Cl2
D.
PH3
E.
CH2O


12.
A molecule with the formula AX3E uses _________ to form its bonds.
A.
s and p atomic orbitals
B.
sp3 hybrid orbitals
C.
sp2 hybrid orbitals
D.
sp hybrid orbitals
E.
sp3d2 hybrid orbitals


13.
Valence bond theory predicts that tin will use _____ hybrid orbitals in SnF5–.
A.
sp2
B.
sp3
C.
sp3d
D.
sp3d 2
E.
sp3d2


14.
Valence bond theory predicts that bromine will use _____ hybrid orbitals in BrF5.
A.
sp2
B.
sp3
C.
sp3d
D.
sp3d 2
E.
none of the above


15.
According to valence bond theory, which of the following molecules involves sp2 hybridization of orbitals on the central atom (underlined and bold)?
A.
C2H2
B.
C2H4
C.
C2H6
D.
CO2
E.
H2O


16.
According to valence bond theory, the triple bond in ethyne (acetylene, C2H2) consists of
A.
three σ bonds and no π bonds.
B.
two σ bonds and one π bond.
C.
one σ bond and two π bonds.
D.
no σ bonds and three π bonds.
E.
none of the above.


17.
According to molecular orbital theory, what is the bond order in the O2+ ion?
A.
5.5
B.
5
C.
4
D.
2.5
E.
1.5


18.
Which of the following statements relating to molecular orbital (MO) theory is incorrect?
A.
Combination of two atomic orbitals produces one bonding and one antibonding MO.
B.
A bonding MO is lower in energy than the two atomic orbitals from which it is formed.
C.
Combination of two 2p orbitals may result in either σ or π MOs.
D.
A species with a bond order of zero will not be stable.
E.
In a stable molecule having an even number of electrons, all electrons must be paired.


19.
The nitrosonium ion, NO+, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO+ is correct?
A.
NO+ has a bond order of 2 and is paramagnetic.
B.
NO+ has a bond order of 2 and is diamagnetic.
C.
NO+ has a bond order of 3 and is paramagnetic.
D.
NO+ has a bond order of 3 and is diamagnetic.
E.
None of the above statements is correct.


20.
A carbon-carbon double bond in a molecule may give rise to the existence of cis and trans isomers.
A. True
B. False


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