Houston Community College System
Chemistry 1405
PRACTICE EXAM # 2
1
HOUSTON COMMUNITY COLLEGE
CHEM 1405
Name: _____________________
Practice Exam # 2 (Chap. 4 - 7)
PART I – Multiple choice: (3 points each)
1) Which is the subatomic particle having a negligible mass and a negative charge?
A) electron
B) neutron
C) proton
D) quark
2) What is the electron configuration for an atom of fluorine?
A) 1s2 2s2 2p3
B) 1s2 2s2 2p5
3) How many neutrons are in the nucleus of an atom of
A) 50
C) 1s2 2s2 2p6 3s1
118
50
D) 1s2 2s2 2p6 3s2 3p5
Sn ?
B) 68
C) 118
D) 168
4) Given that the only naturally occurring isotope of sodium is 23Na, what is its isotopic mass?
A) 11.00 amu
B) 11.99 amu
C) 12.00 amu
D) 22.99 amu
5) What is the term for the minimum amount of energy to remove an electron from a neutral atom in the gaseous state?
A) atomic energy
B) electron energy
C) ionization energy
D) nuclear energy
C) Br
D) all of the above
6) Which of the following is a representative element?
A) B
B) Be
7) Which fourth period transition element has the highest atomic number?
A) Ca
B) Cd
C) Kr
D) Zn
C) Sb and Te
D) Po and At
C) Ca
D) none of the above
8) Which of the following elements are fourth period metalloids?
A) Si and Ge
B) Ge and As
9) Which of the following is an alkali metal?
A) Al
B) Fe
10) How many valence electrons does the representative element with the electron configuration
1s22s22p63s23p5 possess?
A) 5
B) 6
11) The compound Au2Se3 is classified as which of the following?
A) binary ionic
B) ternary ionic
C) 7
D) 2
C) binary molecular
D) binary acid
12) Which of the following formulas for an ionic compound is incorrect as written?
A) Ca(SO4)2
B) KOH
C) MgS
2
D) NH 4Cl
13) Which of the following names is paired with an incorrect formula?
A) Lithium bromide –LiBr
B) Iron (III) chloride - FeCl3
C) Copper (II) oxide - Cu2O
D) Cesium sulfide - Cs2S
C) Iron (II) sulfate
D) Iron (III) sulfide
14) The correct name for Fe2(SO4)3 is
A) Iron (III) sulfate
B) Iron (II) sulfide
15) Element X has two natural isotopes: X-6 (6.015 amu) and X-7 (7.016 amu). Calculate the atomic mass of element X
given the abundance of X-7 is 92.5%.
A) 6.09 amu
B) 6.50 amu
C) 6.52 amu
D) 6.94 amu
16) Which of the following is not isoelectronic with a noble gas?
A) Li
1+
B) Ba2+
C) S1-
D) F1-
17) What is the name of a reaction in which two cations in different compounds exchange anions?
A) combination
B) decomposition
C) double replacement
D) neutralization
18) Which of the following is evidence for a chemical reaction?
A) A gas is detected.
B) A precipitate is formed.
C) A flame is observed.
D) all of the above
19) Which of the statements below best describes the following reaction?
Na2CO3(s)  Na2O(s) + CO2(g)
A) Solid sodium carbonate is heated to give solid sodium oxide and carbon dioxide gas.
B) Sodium carbonate decomposes to sodium oxide and carbon dioxide.
C) Sodium carbonate decomposes to sodium oxide and carbon dioxide gas.
D) Sodium carbonate is heated to give sodium oxide and carbon dioxide.
20) What is the coefficient of oxygen gas after balancing the following equation?
A) 1
B) 2
___P(s) + ___O2 (g) → ___P2O3(s)
C) 3
3
D) 5
PART II – Show All Your Work: (8 points each)
1) What is the predicted product from the following reaction? Balance this equation. What kind of reaction is it?
Barium chloride (aq) + Sodium sulfate(aq) 
2) A) Which of the following metals does not react with aqueous Ni (NO3)2? Why?
Partial Activity Series: Mg > Al > Ni > (H) >Cu
B) Write the core electron configurations for the following:
1) O
2) Mg
3) What is the name of each compound?
A) Ca(OH)2
B) KCl
C) AlBr3
D) NaF
4) How many valence electrons do atoms with the following electron configurations have?
A) 1s22s22p63s23p64s23d104p4
B) 1s22s22p63s2
C) 1s22s22p63s23p64s1
D) 1s22s22p6
5) Fill in the chart below for each of the following isotopes.
Symbol
131
53I
_____
37
17Cl
_____
Atomic #
Mass #
______
_____
______
______
______
99
______
______
43
43
______
26
#Protons #Neutrons
_____
17
56
______
20
______
4
#Electrons
______
23
BONUS QUESTION – Show All Your Work: (10 points)
The hypothetical element supposium exists in four isotopic forms. The relative masses and percentage
isotopes are, respectively,
66.0 amu and 1.230%
67.0 amu and 9.800%
69.0 amu and 2.410%
70.0 amu and 86.56%
abundances for these four
Calculate the atomic mass of supposium.
Answer Key
Part I- Multiple Choice
1) A
8) B
15) D
2) B
9) D
16) C
3) B
10) C
17) C
4) D
11) A
18) D
5) C
12) A
19) A
6) D
13) C
20) C
Part II- Show Your Work
1) Bacl2 (aq) + Na2 SO4 (aq) --> 2 NaCl (aq) + BaSO4 (s)
Double-Replacement Reaction
2) A)Cu, because it is not as active as Ni
B) 1) [He] 2s2 2p4
2) [Ne] 3s2
3) A) Calcium Hydroxide
B) Potassium Chloride
C) Aluminum Bromide
D) Sodium Fluoride
4)
A) 6
131
5)
C) 1
D) 6
53
131
53
78
53
43Tc
43
99
43
56
43
37
17Cl
17
37
17
20
18
26
56
26
30
23
99
53I
B) 2
56
+3
26Fe
Bonus Question:
0.01230  66.0 amu 
0.812 amu
0.09800  67.0 amu 
6.57 amu
0.02410  69.0 amu 
1.66 amu
0.8656  70.0 amu 
60.59 amu
69.632 amu (calc)
69.63 amu (corr)
5
7) D
14) A