When the cations Na + , K + , Rb + , Cs + are combined with chloride ion in the gas phase to form ion pairs, which pair formation releases the greatest amount of energy? A) KCl B) All release the same...

When the cations Na⁺, K⁺, Rb⁺, Cs⁺ are combined with chloride ion in the gas phase to form ion pairs, which pair formation releases the greatest amount of energy?
A) KCl
B) All release the same amount of energy
C) RbCl
D) NaCl
E) CsCl
2.
Which of the following processes is not exothermic?
A) K⁺(g) + e^- ? K(g)
B) K⁺(g) + I^-(g) ? KI(s)
C) I(g) + e^- ? I^-(g)
D) K(g) ? K(s)
E) ½I₂(g) ? I(g)
3.
Which of the following compounds would be expected to have the lowest melting point?
A) AlF₃
B) RbF
C) NaF
D) MgF₂
E) CaF₂
4.
All of the following species have ground-state noble-gas electron configurations except
A) Ge⁴⁺
B) K⁺
C) Kr
D) I^-
E) P^3-
5.
In which of the following lists do the ions not appear in order of increasing ionic radius?
A) S^{2- - +}
B) Na^{+ - 2-}
C) Cl^{- - -}
D) Li^{+ + +}
E) Al^{3+ 2+ +}
6.
An atom of which of the following elements has the highest electronegativity?
A) K
B) As
C) Ba
D) Si
E) Br
7.
How many valence electrons are there in the trifluoroacetate ion, CF₃COO^-
A) 41
B) 42
C) 54
D) 56
E) 40
8.
The number of valence electrons in the nitrite ion is
A) 22
B) 16
C) 23
D) 18
E) 24
9.
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.
10.
In which of the following species is resonance most likely to take place?
A)
B)
C)
D)
E)
11.
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
12.
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
13.
Which of the following species has the shortest bond distance?
A) NO^-
B) O₂
C) CO
D) F₂
E) Cl₂
14.
The molecular geometry of the ammonium ion, NH₄⁺, is most similar to the molecular geometry of
A) NH₃
B) CH₄
C) N₂H₄
D) NH₂^-
E) CH₃⁺
15.
What is the molecular geometry of the thiosulfate ion, S₂O₃^2–?
A) tetrahedral
B) trigonal bipyramidal
C) pyramidal
D) bent
E) square planar
16.
What is the molecular geometry of the bromate ion, BrO₃^–?
A) square planar
B) trigonal planar
C) square pyramidal
D) tetrahedral
E) trigonal pyramidal
17.
When a carbon atom has sp³ hybridization, it has
A) one p bond and three s bonds
B) two p bonds and two s bonds
C) three p bonds and one s bond
D) four s bonds
E) four p bonds
18.
What is the bond order of He₂⁺?
A) ½
B) 1½
C) 1
D) 0
E) 2
19.
Which molecule or ion has the shortest bond length?
A) F₂^-
B) O₂
C) O₂^2-
D) N₂
E) F₂
20.
Which of the following electron distributions among the molecular orbitals best describes the NO molecule?

s2s

s2s*

p2py=p2px

s2pz

p2py*=p2px*

s2pz*

A) 2, 2, 4, 1, 3, 0
B) 2, 2, 4, 2, 4, 1
C) 2, 2, 4, 2, 1, 0
D) 2, 2, 4, 2, 2, 0
E) 2, 2, 4, 2, 4, 2