Chapter 9 2 How many valence electrons are present in the Lewis

71. Which one of the following has a Lewis formula most similar to that of NO–?

A)

O2

B)

O22–

C)

O2–

D)

NO+

E)

NO

72. The Lewis structure for each of the following except ____contains at least one double bond.

A)

O2

B)

CS2

C)

C2H4

D)

NO+

E)

N2H2

73. The Lewis structure for each of the following species except ____ contains a triple bond.

A)

N3–

B)

N2

C)

HCCH

D)

NO+

E)

O22+

74. How many valence electrons are present in the Lewis formula for the hypochlorite ion,

?

A)

20

B)

12

C)

18

D)

14

E)

16

75. What is the total number of valence electrons in the ?

A)

20

B)

12

C)

16

D)

22

E)

18

76. What is the total number of valence electrons in the nitrosyl ion, ?

A)

11

B)

13

C)

10

D)

12

E)

14

77. How many valence electrons are there in the tetraethylammonium ion, ?

A)

56

B)

32

C)

16

D)

57

E)

48

78. What is the total number of valence electrons in the monohydrogen phosphate ion,

?

A)

30

B)

28

C)

32

D)

34

E)

36

79. How many valence electrons does a nitrate ion have?

A)

30

B)

28

C)

24

D)

32

E)

22

80. How many valence electrons are there in the acetate ion, ?

A)

23

B)

24

C)

36

D)

38

E)

22

81. The total number of valence electrons in a peroxide ion, , is

A)

2.

B)

12.

C)

14.

D)

13.

E)

15.

82. The number of valence electrons in the perfluoropropionate ion, , is

A)

60.

B)

62.

C)

66.

D)

80.

E)

58.

83. The total number of valence electrons in the tetrathionate ion, S4O62–, is

A)

58.

B)

60.

C)

56.

D)

54.

E)

62.

84. The number of valence electrons in the nitrite ion is

A)

22.

B)

16.

C)

23.

D)

18.

E)

24.

85. The total number of valence electrons in the phosphate ion is

A)

32.

B)

30.

C)

24.

D)

28.

E)

26.

86. What is the total number of valence electrons in the sulfite ion?

A)

30

B)

26

C)

24

D)

8

E)

32

87. In the Lewis formula for hydrazinium ion, N2H5+, the total number of lone electron pairs

around the two nitrogen atoms is

A)

0.

B)

4.

C)

3.

D)

1.

E)

2.

88. In the Lewis formula for the hydroxide ion, OH–, the number of lone pairs of electrons

around the oxygen atom is

A)

3.

B)

1.

C)

2.

D)

0.

E)

4.

89. The concept of resonance describes molecular structures

A)

that have several different geometric arrangements.

B)

that have delocalized bonding.

C)

that are formed from hybridized orbitals.

D)

that have different molecular formulas.

E)

that have electrons resonating.

90. All the following statements about resonance are true except

A)

A single Lewis formula does not provide an adequate representation of the

bonding.

B)

Resonance describes a more stable situation than does any one contributing

resonance formula.

C)

Resonance describes the oscillation and vibration of electrons.

D)

The contributing resonance formulas differ only in the arrangement of the

electrons.

E)

Resonance describes the bonding as intermediate between the contributing

resonance formulas.

Test Bank General Chemistry, 10th edition 26

91. In which of the following species is resonance most likely to take place?

A)

B)

C)

D)

E)

92. For the resonance hybrid of the nitrite ion,

what is the average number of bonds between the nitrogen atom and an oxygen atom?

A)

3/2

B)

1

C)

4/3

D)

2

E)

5/3

93. Which one of the following species is best described by writing three equivalent Lewis

formulas?

A)

SO3

B)

SF4

C)

SO42–

D)

SO32–

E)

SOF4

Test Bank General Chemistry, 10th edition 27

94. For each of the following species except ____, the electronic structure may be adequately

described by two resonance formulas.

A)

O3

B)

SO32–

C)

NO2–

D)

C6H6

E)

SO2

95. Which of the following are two appropriate resonance formulas for the acetate ion,

CH3CO2–?

A)

B)

C)

D)

E)

96. The electronic structure of which of the following species cannot be adequately described by

a single Lewis formula?

A)

CS2

B)

POF3

C)

HNNH

D)

NO3–

E)

H2NNH2

97. Which of the following species represents an exception to the octet rule?

A)

SiO2

B)

HBr

C)

SF4

D)

PCl3

E)

CO2

98. The Lewis structure of a molecule has a high probability of violating the octet rule if

1.

the molecule has an odd number of valence electrons.

2.

the central atom is surrounded by more than four atoms or eight valence

electrons.

3.

the central atom is from Group 2A or 3A.

A)

1 only

B)

2 only

C)

3 only

D)

1 and 2

E)

1, 2, and 3

99. In which of the following molecules is the octet rule violated?

A)

SF6

B)

OF2

C)

ClF

D)

PF3

E)

SiF4

100. The octet rule is violated by at least one atom in all the following compounds except

A)

SF6.

B)

PF6–.

C)

BrF5.

D)

ICl2–.

E)

SiF4.

101. The Lewis formula of which species does not represent an exception to the octet rule?

A)

SiF5–

B)

SCl6

C)

SF4

D)

BF3

E)

CF3–

102. Which species has the largest number of lone pairs of electrons around the central atom?

A)

XeF2

B)

XeF6

C)

XeOF4

D)

XeF4

E)

SiF62–

103. In the Lewis formula for ClF3, how many lone pairs are around the central atom?

A)

0

B)

4

C)

3

D)

2

E)

1

104. Which of the following molecules has an incorrect Lewis formula?

A)

B)

C)

D)

E)

105. In the Lewis dot formula for ICl2–, the number of lone pairs of electrons around the central

iodine atom is

A)

2.

B)

4.

C)

1.

D)

3.

E)

0.

106. Which of the following has an incomplete octet in its Lewis structure?

A)

SO2

B)

F2

C)

NO2

D)

ICl

E)

CO2

107. Which of the following Lewis structures best describes BF3?

A)

B)

C)

D)

E)

108. Which of the following species represents an exception to the octet rule?

A)

BF3

B)

BF4–

C)

CH3OH

D)

CCl4

E)

PH3

109. From a consideration of the Lewis structure of the thiocyanate ion, SCN–, in which carbon

has a double bond with both the sulfur and nitrogen atoms, the formal charges on the sulfur,

carbon, and nitrogen atoms are, respectively,

A)

–1, +1, –1.

B)

–2, 0, +1.

C)

–1, 0, 0.

D)

–2, +1, 0.

E)

0, 0, –1.

110. Which of the following is/are true concerning formal charge?

1.

The formal charge of each individual atom in a molecule or ion is an actual

atomic charge that can be experimentally determined.

2.

The formal charge of each individual atom is always the same for each

possible resonance form.

3.

The sum of the formal charges of each atom in a molecule or ion equal the

overall charge of the molecule or ion.

A)

1 only

B)

2 only

C)

3 only

D)

1 and 2

E)

none

111. In the Lewis formula that minimizes formal charge, what is the formal charge on the sulfur

atom in sulfur trioxide, SO3?

A)

+2

B)

+4

C)

+6

D)

–2

E)

0

112. Which of the following statements is true concerning the Lewis formula that minimizes

formal charge for H2SO4?

A)

The formal charge of S is +2, the formal charge of each O is 0, and the formal

charge H is 0.

B)

The formal charge of S is +2, the formal charge of O is either 0 or –2, and the

formal charge of H is +1.

C)

The formal charge of S is +2, the formal charge of O is either 0 or –2, and the

formal charge of H is 0.

D)

The formal charge of S is +2, the formal charge of O is 0, and the formal charge of

H is +1.

E)

The formal charge of S is 0, the formal charge of O is 0, and the formal charge of

H is 0.

113. In which of the following species is the octet rule violated by the central atom when the

central atom has a formal charge of zero?

A)

SOCl2

B)

CCl4

C)

H2S

D)

PF3

E)

N2F4

114. What is the correct Lewis dot formula for sulfuric acid, H2SO4, that minimizes formal

charge?

A)

B)

C)

D)

E)

115. What is the formal charge on the chlorine atom in the chlorate ion, ClO3–, in the Lewis dot

formula that minimizes formal charge?

A)

–2

B)

+1

C)

0

D)

–1

E)

+2

Test Bank General Chemistry, 10th edition 35

116. In the Lewis dot formula that minimizes formal charge, how many bonds are there in the

tetrathionate ion, S4O62– ?

A)

7

B)

9

C)

15

D)

11

E)

13

117. In the Lewis dot formula for the bromate ion (BrO3–) that minimizes formal charge, the

central atom is surrounded by

A)

two bonding pairs and two lone pairs of electrons.

B)

four bonding pairs and one lone pair of electrons.

C)

three bonding pairs and no lone pairs of electrons.

D)

five bonding pairs and one lone pair of electrons.

E)

three bonding pairs and one lone pair of electrons.

118. Which Lewis dot formula for pyrophosphate, P2O74–, minimizes formal charge?

A)

B)

C)

D)

E)

119. As the number of bonds between two carbon atoms increases, which of the following

decrease(s)?

A)

only the bond length

B)

only the bond energy

C)

only the number of electrons between the carbon atoms

D)

all of these

E)

none of these

120. Which of the following statements is true?

A)

The triple bond in N2 has a smaller bond order and a smaller bond length than the

single bond in F2.

B)

The triple bond in N2 has a larger bond order and a smaller bond length than the

single bond in F2.

C)

The triple bond in N2 has a smaller bond order and a larger bond length than the

single bond in F2.

D)

The triple bond in N2 has a larger bond order and a larger bond length than the

single bond in F2.

E)

The triple bond in N2 and the single bond in F2 have the same bond order and the

same bond length.

121. Which of the following species has the shortest bond distance?

A)

F2

B)

Cl2

C)

Br2

D)

I2

E)

H2

122. Which of the following diatomic species do you expect to have the longest bond length?

A)

O2+

B)

O22–

C)

O2

D)

O2−

E)

they are all identical

123. Which of the following diatomic molecules has the greatest bond energy?

A)

H2

B)

HCl

C)

Cl2

D)

CO

E)

HF

124. Consider the reaction

2HCl(g) → H2(g) + Cl2(g); H = 185 kJ

Which of the following statements is false?

A)

The reaction is endothermic.

B)

HCl(g) has a negative enthalpy of formation.

C)

The products have more enthalpy than the reactants.

D)

The HCl bond is longer than either the H2 bond or the Cl2 bond.

E)

The bond order of each of the products is one.

Test Bank General Chemistry, 10th edition 38

125. Using bond-energy data, what is H for the following reaction?

CH4(g) + 2Cl2(g) → CCl4(g) + 2H2(g)

Bond

Bond Energy (kJ/mol)

C-H

413

H-H

432

Cl–Cl

242

C-Cl

328

A)

–40 kJ

B)

–150 kJ

C)

40 kJ

D)

1415 kJ

E)

150 kJ

126. Using bond-energy data, what is H for the following reaction?

CH3OH(g) + H2S(g) → CH3SH(g) + H2O(g)

Bond

Bond Energy (kJ/mol)

C-H

413

C-O

358

O-H

463

C-S

259

S-H

339

A)

–25 kJ

B)

−124 kJ

C)

25 kJ

D)

–2763 kJ

E)

2738 kJ

127. Based on the following data, what is the Br-Br bond energy?

H2(g) + Br2(g) → HBr(g); H = –36.44 kJ

Bond

Bond Energy (kJ/mol)

H-H

435

H-Br

362

Test Bank General Chemistry, 10th edition 39

A)

399 kJ/mol

B)

216 kJ/mol

C)

–216 kJ/mol

D)

–289 kJ/mol

E)

289 kJ/mol

128. Based on the following data, what is the bond energy of the C=C bond in 1,1–

difluoroethylene, CF2CH2?

CH4(g) → C(g) + 4H(g); H = 1656 kJ

CF4(g) → C(g) + 4F(g); H = 1756 kJ

CF2CH2(g) → 2C(g) + 2H(g) + 2F(g); H = 2317 kJ

A)

611 kJ/mol

B)

845 kJ/mol

C)

820 kJ/mol

D)

1706 kJ/mol

E)

1910 kJ/mol

129. Which of the following covalent molecules does not have the proper Lewis dot formula?

A)

B)

C)

D)

E)

130. Use the bond energies provided to complete the following statement.

________ when all of the bonds in acetic acid (CH3COOH) are broken.

Bond

Bond Energy (kJ/mol)

C-H

413

C-O

358

O-H

463

C=O

745

C-C

348

C=C

614

A)

3153 kJ/mol of energy is consumed

B)

3153 kJ/mol of energy is released

C)

2805 kJ/mol of energy is released

D)

2805 kJ/mol of energy is consumed

E)

2766 kJ/mol of energy is consumed