Oxidation-Reduction Reactions
Practice Test
1.
When sodium reacts with sulfur to form sodium sulfide, each sulfur atom ________________.
a.
loses one electron
b.
gains one electron
c.
loses six electrons
d.
gains two electrons
2.
What is the oxidation number of iron in Fe
2
O
3
?
a.
1+
b.
2-
c.
3+
d.
2+
3.
Which of the following describes oxidation?
a.
loss of electrons
b.
gain of positive charge
c.
gain of electrons
d.
loss of positive charge
4.
What is the reducing agent in the reaction Cu(s) + 2AgNO
3
(aq)
2Ag(s) + Cu(NO
3
)
2
(aq)?
a.
Cu
b.
NO
3
1-
c.
Ag(s)
d.
Ag
1+
5.
What chemical species is oxidized in the reaction represented by the unbalanced equation H
2
O
2
(l) + Br
-
(aq)
Br
2
(aq) + H
2
O(l)?
a.
H
2
O
2
b.
H
2
O
2
c.
Br
-
d.
O
-
6.
What is the oxidation number of oxygen as a free element?
a.
0
b.
2-
c.
2+
d.
1-
7.
The fixer used in black-and-white photography contains ________________.
a.
barium ions
b.
chloride ions
c.
sulfur atoms
d.
thiosulfate ions
8.
What is the oxidizing agent in the reaction Cu(s) + 2AgNO
3
(aq)
2Ag(s) + Cu(NO
3
)
2
(aq)?
a.
Ag(s)
b.
NO
3
1-
c.
Ag
1+
d.
Cu
9.
When aluminum metals reacts with the tarnish on silver, products of the reaction include ____________.
a.
Ag
+
and Al
b.
Ag and Al
3+
c.
Al and OH
-
d.
Ag and H
+
10.
What is the oxidation number of chlorine in KClO
3
?
a.
1-
b.
1+
c.
3+
d.
5+
11.
_______ are reduced when black-and-white photographic film is exposed to light.
a.
Br
1-
ions
b.
Ag
1+
ions
c.
Ag atoms
d.
Br atoms
12.
As ethanol is oxidized in a breathalyzer, chromium in orange dichromate ions is reduced to ________________.
a.
black Cr atoms
b.
blue-green Cr
3+
ions
c.
colorless Cr
6+
ions
d.
yellow Cr
4+
ions
13.
A reaction in which _____________ are lost and gained is an oxidation-reduction reaction.
a.
protons
b.
neutrons
c.
electrons
d.
hydrogen ions
14.
Large deposits of solid, elemental __________ are formed in redox reactions near the vents of some volcanoes.
a.
hydrogen
b.
sulfur
c.
oxygen
d.
chlorine
15.
___________ reduces iron ore to iron in a blast furnace.
a.
oxygen
b.
calcium carbonate
c.
Carbon monoxide
d.
calcium
16.
________________ reactions release light energy at room temperature.
a.
Chemiluminescent redox
b.
Double-replacement
c.
All redox
d.
decomposition
17.
Most bleaches utilize reactions involving this chemical species.
a.
Cl
2
b.
ClO
3
1-
c.
ClO
1-
d.
NaOH
18.
What chemical species is reduced in the reaction described in question 23?
a.
Br
-
b.
H
2
O
2
c.
Br
2
d.
O
-
19.
The vitamin C in lemons is a/an ______________.
a.
corrosive compound
b.
carbohydrate
c.
good antioxidant
d.
oxidizing agent
20.
Bleach removes stain from clothing by ___________ colored molecules.
a.
reducing
b.
dissolving
c.
protecting
d.
oxidizing
21.
Which type of can takes the longest to degrade?
a.
tin
b.
aluminum
c.
steel
d.
iron
22.
Which element is oxidized in the reaction BaCl
2
(aq) + Na
2
SO
4
(aq)
2NaCl(aq) + BaSO
4
(s)?
a.
Na
b.
Ba
c.
none
d.
Cl
23.
Luminol is used in a preliminary test for _______________.
a.
saliva
b.
milk
c.
clay
d.
blood
24.
How does paint protect steel surfaces from corrosion?
a.
Paint acts as a sacrificial anode.
b.
Paint galvanizes steel.
c.
Paint prevents the oxidation-reduction reaction of corrosion from occurring.
d.
Paint corrodes leaving steel intact.
25.
Determine the net change in oxidation number of chlorine in the following reaction: ClO4- (aq) + Br- (aq) ® Cl- (aq) + Br2(g) (in acid solution)
a.
8
b.
-7
c.
-8
d.
7
26.
Sodium __________ when it reacts with sulfur to form sodium sulfide.
a.
is oxidized
b.
gains one electron
c.
is reduced
d.
gains two electrons
27.
What chemical species is the reducing agent in the reaction described in question 23?
a.
H
2
O
2
b.
Br
-
c.
O
-
d.
Br
2
28.
Some organisms use redox reactions to produce light in a process known as ______________.
a.
photolysis
b.
photosynhesis
c.
bioluminescence
d.
respiration
