AnswersTX-Chemistry B-Credit Recovery Summer SchoolUnit Test

Unit Test — Unit test Answers

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Which of the following is not an oxidation-reduction reaction?

A
XeF6(s) XeF4(s) + F2(g)
Option A
B
2Cs(s) + I2(g) 2CsI(s)
Option B
C
2H2SO4(aq) + 2Ba(OH)2(aq) 2BaSO4(s) + 4H2O(l)
Option C
D
Zn(s) + 2AgNO3(aq) Zn(NO3)2(aq) + Ag(s)
Option D
2
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Which rule for assigning oxidation numbers is correct?

A
Hydrogen is usually –1.
B
Oxygen is usually –2.
C
A pure group 1 element is +1.
D
A monatomic ion is 0.
3

What describes the change in oxidation states of the following reaction?

Question illustration
A
Cu2+ reduces to Cu, and Al oxidizes to AI3+.
B
Cu2+ oxidizes to Cu, and Al reduces to AI3+.
C
Cu2+ is the reducing agent, and Al is the oxidizing agent.
D
Cu is the reducing agent, and AI3+ is the oxidizing agent.
4

Consider the half reactions below for a chemical reaction.What is the overall equation for this chemical reaction?

Question illustration
A
Upper Z n (s) plus upper C u superscript 2 plus (a q) right arrow upper Z n superscript 2 plus (a q) plus upper C u (s).
Option A
B
Upper Z n (s) plus upper C u superscript 2 plus (a q) right arrow upper C u superscript 2 plus (a q) plus upper Z n (s).
Option B
C
Upper Z n superscript 2 plus (a q) plus upper C u (s) right arrow upper C u superscript 2 plus (a q) plus upper Z n (s).
Option C
D
Upper Z n superscript 2 plus (a q) plus 2 e superscript minus right arrow upper C u superscript 2 plus (a q) plus 2 e superscript plus.
Option D
5

The following equations are half reactions and reduction potentials. Li+ (aq) + e– Li(s) has a reduction potential of –3.04 V F2(g) + 2e– 2F–(aq) has a reduction potential of +2.87 VNow consider lithium (LI+) and fluoride (F2) as oxidizing agents. How do these compare as oxidizing agents?

Question illustration
A
Lithium is a stronger oxidizing agent than fluoride.
B
Fluoride is a stronger oxidizing agent than lithium.
C
Fluoride and lithium have the same oxidizing strength.
D
Reduction potential and oxidizing/reducing strength are unrelated.
6

The reaction below was carried out in an acidic solution.Which statement is true about this equation?

Question illustration
A
Although it is unbalanced, it can be balanced by using the half-reaction method.
B
It has been balanced by using the half-reaction method.
C
It has been balanced by directly using spectator ions.
D
Although it is unbalanced, it can be balanced by directly using spectator ions.
7

What is the oxidation number for N in the compound NH3? (Recall that H usually has an oxidation number of +1.)

A
–3
B
–1
C
0
D
+3
8

Which answer best describes what is happening in the following redox reaction?4Fe + 3O2 2Fe2O3

Question illustration
A
This is combustion.
B
This is neutralization.
C
Iron is oxidized to form rust.
D
Oxygen is oxidized to form rust.
9

Consider the reaction below.What is being reduced?

Question illustration
A
only K
B
only Br2
C
both K and Br2
D
neither K nor Br2
10

Consider the half reaction below.Which statement best describes what is taking place?

Question illustration
A
Chlorine is losing electrons and being oxidized.
B
Chlorine is losing electrons and being reduced.
C
Chlorine is gaining electrons and being oxidized.
D
Chlorine is gaining electrons and being reduced.
11

What must be true of a disproportionate substance?

A
It is composed of oxygen.
B
It is both a reactant and a product.
C
It has an oxidation number of 0.
D
It gains and loses electrons.
12

Read the table below.Reduction Half-ReactionStandard Reduction Potential (V)What is the overall reaction potential for the reaction below?Ag+(aq) + Cu(s) Ag(s) + Cu2+(aq)

Question illustration
A
0.46 V
Option A
B
+0.46 V
C
+0.57 V
D
+1.14 V
13

The information below describes a redox reaction.What is the final, balanced equation for this reaction?

Question illustration
A
2 upper C r superscript 3 plus (a q) plus 6 upper C l superscript minus (a q) right arrow 2 upper C r (s) plus 3 upper C l subscript 2 (g).
Option A
B
2 upper C r superscript 3 plus (a q) plus 2 upper C l superscript minus (a q) plus 6 e superscript minus right arrow upper C l subscript 2 (g) plus 2 upper C r (s).
Option B
C
Upper C r superscript 3 plus (a q) plus 6 upper C l superscript minus (a q) plus 3 e superscript minus right arrow 2 upper r (s) plus 3 upper C l subscript 2 (g).
Option C
D
Upper C r superscript 3 plus (a q) plus 2 upper C l superscript minus (a q) right arrow upper C r (s) plus upper C l subscript 2 (g).
Option D
14

Equations can be balanced by using the half-reaction method. Which step should be completed immediately after finding the oxidation states of atoms?

A
inserting the coefficients
B
balancing the half reactions
C
identifying the half reactions
D
inspecting the number of atoms
15

Which identifies an oxidation-reduction reaction?

A
a double replacement reaction
B
a neutralization reaction
C
a reaction in which oxidation numbers change
D
a reaction in which no electrons are transferred
16

Which is an important step in the alternate method for balancing equations in redox reactions?

A
indicating the types of bonds found in the molecules
B
determining the speed at which reactions take place
C
determining the half reactions of chemical equations
D
indicating the temperature at which the reaction occurs
17

Consider the redox reaction below.Which equation is a half reaction that describes the reduction that is taking place?

Question illustration
A
Upper F e superscript 2 plus (a q) plus 2 e superscript minus right arrow upper F e (s).
Option A
B
Upper M g (s) right arrow upper M g superscript 2 plus (a q) plus 2 e superscript minus.
Option B
C
Upper Fe superscript 2 plus (a q) right arrow upper F e (s) plus 2 e superscript minus.
Option C
D
Upper M g (s) plus 2 e superscript minus right arrow upper Mg superscript 2 plus (a q).
Option D
18

In the reaction equation BrO(aq) Br–(aq) + BrO(aq), how many oxidation states does the disproportionate substance have throughout the reaction?

Question illustration
A
0
B
1
C
2
D
3
19

Which half-reaction correctly describes an oxidation?

A
Upper C a (s) plus 2 e superscript minus right arrow upper C a superscript 2 plus (a q).
Option A
B
Upper B r subscript 2 plus 2 e superscript minus right arrow 2 upper B r superscript minus.
Option B
C
Upper N a superscript plus (a q) right arrow upper N a (s) plus e superscript minus.
Option C
D
Upper C r (s) right arrow upper C r superscript 3 plus (a q) plus 3 e superscript minus.
Option D
20

Consider the half reaction below.Which statement best describes what is taking place?

Question illustration
A
Copper is being oxidized.
B
Copper is being reduced.
C
Copper is losing electrons.
D
Copper is a reducing agent.

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