Download key to sample questions test 2

CHEMISTRY 207
SAMPLE TEST QUESTIONS
KEY
1. Circle the correct answer.
a. Which one of the following does not have resonance structures?
b, Which one of the following has a square pyramid shape?
c. Which one of the following molecules has a net dipole moment. The shape of the molecule is
given below in parentheses.
CF4
CH4
BH3
SO2
(tetrahedral)
(tetrahedral)
(bent)
(trigonal planar)
d.
Which of the following is probably NOT a stable compound
PH3
MgO
MgF3
e. Which of the following molecules has the biggest dipole moment?
H2
BrCl
HF
Li2O
IBr
f. Which one of the following molecules does NOT have a net dipole moment. The shape of the
molecule is given below in parentheses.
SF4
BF2Br
NF3
CO2
(see-saw)
(trigonal planar)
linear
(trigonal pyramid)
g. Which one of the following has sp3 hybridization on the central atom?
h. Which of the following ions is most likely to be stable. (Hint: consider the Lewis structures)
NH
NH2
NH3
NH4
i. Which of the following molecules has a Lewis structure similar to that of N2?
H2
O2
CO
Cl2
j. What is the formal charge on the sulfur atom in the figure on the right?
+1
-1
0
-2
k. Which of the following bonds is least polar?
HF
ClBr
CF
1
OF
CHEMISTRY 207
SAMPLE TEST QUESTIONS
KEY
l. Including the one shown on the right, how many resonance
forms can be drawn for PO43-
O
O
P
O
O
2
m.
n.
o.
3
4
5
How many orbitals are there a set sp hybrid orbitals?
3
4
2
5
Which one of the following is linear?
Which of the following molecules has a net dipole moment
BF3
FCCF
CCl4
trigonal planar
linear
tetrahedral
ICl3
T shaped
p. Select the molecule in which the central atom violates the octet rule
NH3
CO2
BF3
PH3
q. Which of the following is a planar molecule
CH4
BH3
PCl5
NH3
r. A molecule with sp3d hybridization on the central atom
always has a trigonal bipyramid geometry
always has five pairs of electrons or bonded atoms around the central atom
always has five bonds on the central atom
always is a non planar molecule
s.
The angle between the H-N-H bonds in NH3 is closest to
90 o
120 o
109.5 o
180 o
t. Which of the following is the balanced net ionic equation for the precipitation of calcium
phosphate when aqueous solutions of sodium phosphate and calcium chloride are mixed .
2Na3PO4(aq) + 3 CaCl2(aq)  6 NaCl(aq) + Ca3(PO4)2(s)
2 PO4(aq) + 3 Ca(aq)  Ca3(PO4)2(s)
PO4(aq) + Ca(aq)  CaPO4(s)
6 Na(aq) + 2PO4(aq) + 3Ca(aq) +6 Cl(aq)  6 Na(aq) + 6 Cl(aq) + Ca3(PO4)2(s)
u. Which one of the following is an acid base reaction?
2 HCl + Mg  H2 + MgCl2
HCl + KOH  H2O + KCl
C(s) + O2(g)  CO2(g)
S8(s) + 4 Cl2 (g)  4 S2Cl2(l)
v. Which of the following salts is insoluble in water?
FeCl3
Na2CO3
2
Pb(NO3)2
Mn3(PO4)2
CHEMISTRY 207
SAMPLE TEST QUESTIONS
KEY
w. In which of the following molecules does Mn have an oxidation number of +6.
MnS
KMnO4
MnO2
K2MnO4
x. Which of the following reactions is NOT a redox reaction?
Cu(s) + F2(g)  CuF2(s)
K2SO4(aq) + BaCl2(aq)  BaSO4(s) + 2KCl(aq)
2HCl + Mg(s)  H2(g) + MgCl2(aq)
C(s) + O2(g)  CO2(g)
y. Which of the following is a fusion reaction?
7
4
3
2
n
  73 Li
0
1
He  11H  42 He  01
222
86
1
0
Be 
Rn 
235
92
U
218
84
Po  42 He
Te 
137
52
97
40
Zr  201 n
z. The reactions in nuclear reactors can be best characterized as
Fusion
Alpha decay
Fission
aa. In the reaction
alpha particle
27
13
Al  ? 
Gamma decay
Na  42 He , the missing particle must be a(an)
24
11
beta particle
neutron
positron
bb. 232Th undergoes alpha decay. The decay product undergoes a beta decay. What is the
product of the second decay?
228
232
228
228
Rn
Ac
Th
Ac
cc Which of the following types of materials is most dangerous if ingested
Beta emitters
Gamma emitters
Alpha emitters
x-ray emitters
dd What is the missing product for the fission reaction shown below
236
142
91
+
+
?

56 Ba
92 U
36 Kr
three protons
An alpha particle
three neutrons
A beta particle
ee. The half-life for decay of 3H is 11 yr. How many years must pass to reduce a 16.0 gram
sample to 2.0 g.
11 yrs
22 yrs
44 yrs
33 yrs
ff. If an isotope is above the belt of stability in the plot of number of neutrons vs. number of
protons then the isotope will most likely decay by
electron capture
positron emission
alpha emission
beta emission
gg. Which one of the following is a  ( antibonding) orbital?
3
CHEMISTRY 207
hh.
SAMPLE TEST QUESTIONS
KEY
Which one of the following statements is TRUE?
Bond length tends to decrease as bond strength increases
Bond length tends to increase as bond strength increases
Single bonds tend to be shorter than double bonds
Triple bonds tend to be longer than double bonds
__________________________________________________________________________
A
a.
b
c.
d
e.
f.
B
C
D
Which of the diagrams above corresponds to a molecule with a triple bond? __D____
Which of the diagrams above corresponds molecule with no net bonds? ___C_____
Which of the diagrams above could correspond to a N2 molecule? ____D____
Which of the diagrams above corresponds to a paramagnetic molecule? ____B____
Which of the diagrams above corresponds to a molecule with a double bond? __B____
Which of the diagrams above corresponds to a molecule with a single bond? __A____
2. Fill in the blank
a.
How many grams of Na are in 10g of NaOH?
 molNaOH  molNa  22.99gNa 


  5.75g
10gNaOH 
40
g
mol
mol
NaOH 
NaOH 
Na


b.
How many moles of NaCl are in 100 mL of 2 M NaCl (0.100L)(2 mol L-1) = 0.2 mol
c.
The molecule HCN contains _2  bonds and 2_  bonds.
d.
How many moles of hydrogen atoms are in ten moles of Ca(OH)2 ___10x2 = 20
e.
How many S atoms are in two moles of S2Cl2 __2x2x6.02x1023__________
f.
Give the approximate values of the angles shown in the
figure on the right _109.5___,  __120___
4
CHEMISTRY 207
SAMPLE TEST QUESTIONS
KEY
h.
10 mL of a 2.5 M NaCl solution contains __0.025________ moles of NaCl
i.
For CrO4 the oxidation numbers are _+6_ for Cr and __-2___ for O
What is the missing isotope in the following reaction
236
92 U

+
141
56 Ba
?
+
92
36
Kr
3 01n
Balance the following equations
C6H14(l) + 19/2 O2(g)  6 CO2(g) + 7 H2O(l)
2 CH3NH2 (l) + 9/2 O2(g)  2 CO2(g) + 5 H2O(l) + N2(g)
_______________________________________________________________________________
Consider the reaction
S8(s) + 4 Cl2 (g)  4 S2Cl2(l)
If 10.00 g of S8 reacts as completely as possible with 8.00 g of Cl2, how many grams of
S2Cl2(l) will be formed. Show all calculations and report the answer to the correct number of
significant figures.

 4 molS2Cl2  135.03 gS2Cl2 


  21.06 gS Cl
S8
2 2





mol
mol
S8 
S8
S2Cl2



 molCl2  4 molS2Cl2  135.03 gS2Cl2 


  15.2 gS Cl
8.00 gCl2 
2 2
 70.90 gCl  4 molCl  molS Cl

2 
2
2 2



mol
10.00 g  256.5
g

S8

15.2 g will be formed
_______________________________________________________________________________
A compound 69.58% Ba, 6.090% C and 24.32% O. What is its empirical formula?
69.58 gBa 
molBa 
  0.507 molBa
1
37.34
g
Ba 

6.090 gC 
molC 
  0.507 molC
1
2.01
g
C 

24.32 gO 
molO 
  1.52 molO
 16.00 gO 
5
CHEMISTRY 207
Ba
O
C
SAMPLE TEST QUESTIONS
KEY
0.507
 1.0
0.507
1.52
 3.0
0.507
0.507
 1.0
0.507
BaCO3
___________________________________________________________________________
How many grams of C are in 50.0 g. of Na2CO3
FW Na2CO3 = 2x22.99 + 12.01 + 3x16.00 = 105.99 g/mol

 molC  12.01 gC 


  5.67 gC



mol
Na2CO3 
Na2CO3  mol C


_______________________________________________________________________________
50.0 g
Na2CO3
mol
 105.99
g
Na2CO3
What is the molarity of Na2CO3 solution that is made by dissolving 2.0 g of Na2CO3 in 250.00 mL
of water.
2.0 g

Na2CO3

  0.0189 molNa CO
2
3


mol
 105.99
g
Na2CO3
Na2CO3

 0.0189 molNa2CO3  1000 mL 
2


  7.55  10 M
250 mL
L



_______________________________________________________________________________
What is the molarity of the solution made by diluting 25.0 mL of 2.0 M hydrochloric acid to a final
volume of 1.500 L.
M1V1 = M2V2
V
L
 25.0 mL 

M2  M1 1  2.0 M

  0.033 M
V2
 1.500 L  1000 mL 
_______________________________________________________________________________
Write balanced net ionic equations for the following reactions.
K2CO3(aq) and CuCl2(aq) 
Cu2+ + CO32  CuCO3(s)
BaCl2(aq) + AgNO3(aq) 
Ag+ + Cl  AgCl(s)
Write a balanced nuclear equation for each of the following
positron emission by 11C
11
6
C  01  115B
6
CHEMISTRY 207
SAMPLE TEST QUESTIONS
KEY
alpha decay of 218Pb
218
82
Pb  42   214
80 Hg
Draw Lewis structures for the following compounds. Show formal charges and resonance
structures if appropriate.
CH3F
ClO3
HCN
O
O Cl
O
+ two other resonance
structures
ELECTRONEGATIVITIES
H
Li
Na
K
Rb
Cs
2.1
1.0
0.9
0.8
0.8
0.7
Be
Mg
Ca
Sr
Ba
1.5
1.2
1.0
0.9
0.9
B
Al
Ga
In
Tl
2.0
1.5
1.8
1.7
1.8
C
Si
Ge
Sn
Pb
2.5
1.8
1.8
1.8
1.9
N
P
As
Sb
Bi
7
3.0
2.1
2.0
1.9
1.9
O
S
Se
Te
Po
3.5
2.5
2.4
2.1
2.0
F
Cl
Br
I
At
4.0
3.0
2.8
2.5
2.2