CHM 10425 Exam Practice
Exam 3 CH: 5.5, 6, & 8
Practice Exam Version 2
Name___________________________________
Instructions: The exam contains 22 multiple choice questions several short answer questions. The exam time allows for
approximately 2.2 minutes per question . Note: Questions are from textbook -based study guides. To mimic exam
conditions:
Set a timer for 50 minutes
Put away all notes
Turn off phone, laptop/tablet/computer
Complete the exam using only periodic table with constants, scratch paper, pencil, and scientific calculator
Record answers and show work on a separate clean piece of paper
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
Which of the following molecules is polar?
A) BF3
B) PCl3
C) BeCl2
D) CS2
2) Which image(s) in the figure represents a compound that contains covalent bonds?
A)
I only
B) II only
C) II and III
D) II, III, and V
E) V only
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E) CH4
CHM 1025 Exam Practice
Exam 3 CH 5.5, 6, & 8
Practice Exam Version 2
3) Predict the molecular shape and give the approximate bond angles in the PCl3 molecule.
A) trigonal pyramidal, 109.5º
B) trigonal
planar, 120º
C) bent, 120º
D) tetrahedral, 109.5º
E) linear, 180º
4) The Lewis model predicts that the formula for a compound between barium and sulfur is:
A) BaS
B) BaS3
C) Ba2 S
D) BaS2
E) none of the above
5) What is the theoretical yield of a reaction if 25.0 grams of product were actually produced from a reaction that has
a 88% yield?
A) 3.52
B) 28.4
C) 22.0
D) 352
E) none of the above
6) Which Lewis structure below correctly represents the compound formed between magnesium and sulfur?
..
A) Mg 2 [: S :] 2
··
..
..
B) [: S :] Mg 2 [: S :]
··
··
..
C) Mg [: S :] 2 Mg
··
..
D) Mg [: S :]
··
E) none of the above
7) When ethanol, C2 H 5 OH, a component in some gasoline mixtures, is burned in air, one molecule of
ethanol combines with three oxygen molecules to form two CO2 molecules and three H2O molecules.
Select the statement below that is incorrect in regard to this reaction.
A) If 12 H2 O molecules are formed, then 9 O2 molecules must have reacted.
B) If 4 ethanol molecules react, 8 CO2 molecules should form.
2CO2 + 3H2O.
C) The balanced equation for the reaction is C2 H 5 OH + 3O2
D) If 12 CO2 molecules are formed, then 18 H2 O molecules should also form.
E) If 15 ethanol molecules react, then 45 oxygen molecules must also react.
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CHM 1025 Exam Practice
Practice Exam Version 2
Exam 3 CH 5.5, 6, & 8
8) Consider the reaction between sodium metal and chlorine gas to form sodium chloride:
2Na(s) + Cl2 (g)
A) mass
C) atoms
9)
2NaCl(s) Which of the following is not conserved in this reaction?
B) moles of molecules
D) moles of atoms
Which of the following substances has both ionic and covalent bonding?
A) Cl2
B) MgO
C) NaCl
D) MgCO3
E) None of these
10) Identify the main-group element X that could form the compound with the following Lewis structure:
A)
Br
B) S
C)
N
11) Considering the following precipitation reaction:
Pb(NO3 )2 (aq) + 2KI(aq)
PbI2 (s) + 2KNO3 (aq)
Which ion(s) would NOT be present in the net ionic equation?
A) K+ , I-
B) K+, Pb2+
C) Pb2+ , NO3 -
D) K+ , NO3 -
E) All the above ions are in the net ionic equation.
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D)
Si
E) Na
CHM 1025 Exam Practice
Exam 3 CH 5.5, 6, & 8
Practice Exam Version 2
12) Which of the following is the best (simplest) balanced equation to represent the chemical reaction
shown in the figure on any scale?
A) A 2 + B2
AB2
4AB2
B) 2A2 + 4B2
2AB2
C) A 2 + 2B2
4A2 B
D) 2A2 + 4B2
12AB
E) 4A + 8B
13) The total number of electrons to be counted for the Lewis structure of the PO4 3- polyatomic ion is:
A) 32.
B) 26.
C) 29.
D) 8.
E) none of the above
14) How many moles of aluminum are needed to make 9 moles of molecular hydrogen?
Given the reaction: 2 Al + 6 HCl 2 AlCl3 + 3H2
A) 2 moles
B) 4 moles
C) 6 moles
D) 3 moles
E) none of the above
15) How many grams of water are made from the reaction of 16.0 grams of oxygen gas?
Given the reaction: 2H2 + O2 2H2 O
A) 16
B) 9
C) 18
D) 36
E) not enough information
16) Which
of the following molecules or ions should exhibit resonance?
A) C 2 H 2
B) Br2
C) CO
D) CO3
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E) SiH4
CHM 1025 Exam Practice
Exam 3 CH 5.5, 6, & 8
Practice Exam Version 2
17) When writing an ionic equation, how would Mg(NO3 )2 (aq) be represented?
A) Mg(aq) + N2 (aq) + 3O2 (aq)
B) Mg2+(aq) + NO3 – (aq)
C)
Mg2+(aq) + 2N3–(aq) + 6O2–(aq)
D) Mg2+(aq) + 2NO3 – (aq)
E) Mg2+(aq) + (NO3 )2 – (aq)
18) When the equation __Ca3 N2 + __H2 O
A) 6
B) 2
C) 3
D) 12
E) none of the above
__Ca(OH)2 + __NH3 is balanced, the coefficient of H2 O is:
19) How
many single bonds are typically formed by the element I?
A) 1
B) 3
C) 5
D)
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20) How many moles of lithium nitrate are theoretically produced if we start with 3.4 moles of Ca(NO3 )2 and 2.4
moles of Li3 PO4 ?
Reaction: 3Ca(NO3 )2 + 2Li3 PO4
A) 7.2
B) 1.1
C) 6.8
D) 1.2
E) not enough information
6LiNO3 + Ca3 (PO4 )2
21) Which ingredient is the limiting reactant if you have 6 cups of flour, 9 eggs and 2 tbs of oil?
Given: 2 cups flour + 3 eggs + 1 tbs oil 4 waffles
A) waffles
B) eggs
C) oil
D) flour
E) not enough information
.. ..
..
22) The Lewis structure, [: O - N = O ] best represents:
··
··
A) NO2
B) NO2 C) NO2 +
D) both NO2 + and NO2 E) answers A, B, and C
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Answer Key
Testname: CHM1025_EXAM_3PRACTICE_EXAM_V2
1) B
2) D
3) A
4) A
5) B
6) A
7) A
8) B
9) D
10) D
11) D
12) C
13) A
14) C
15) C
16) D
17) D
18) A
19) A
20) C
21) C
22) B
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