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redox reactions

Total questions: 60

Worksheet time: 2hrs 34mins

Name
Class
Date
1.
What element is being Oxidized?
a)
N
b)
H
c)
O
d)
S
2.
What element is being Reduced?
a)
N
b)
H
c)
O
d)
S
3.
If in a reaction, copper is reduced; its number of electrons has:
a)
Increased
b)
Decreased
c)
Remained Constant
d)
Varies Randomly
4.
If an atom loses electrons during a chemical reaction, the atom was:
a)
Oxidized
b)
Reduced
c)
Neutralized
d)
Precipitated
5.
In the reaction
2Ca(s) + O2(g) --> 2CaO(s), calcium is __________
a)
Reduced
b)
Synthesized
c)
Oxidized
d)
None of the above
6.
     In the reaction Zn + H2O --> ZnO2 + H2
 which element, if any, is oxidized? 
a)
Zinc
b)
Hydrogen
c)
Oxygen
d)
None
7.
Another name for a "oxidation-reduction" reaction is
a)
chemical reaction
b)
neutralization reaction
c)
redox reaction
d)
nuclear reaction
8.

A redox reaction is NOT:

a)

all reactions

b)

a combustion reaction

c)

a reduction-oxidation reaction

d)

a reaction in which electrons are transferred from one atom to another

9.

Defined as the loss of electrons.

a)

oxidation

b)

reduction

c)

redox

d)

OIL RIG

10.

Defined as the gain of electrons.

a)

oxidation

b)

redox

c)

reduction

d)

LEO GER

11.

Cl2 + 2e- --> 2Cl - is an example of:

a)

a chemical reaction

b)

redox

c)

oxidation

d)

reduction

12.

An increase in oxidation number.

a)

more acidic

b)

reduction

c)

less basic

d)

oxidation

13.
Is calcium oxidized or reduced in the following reaction? 
2CaO--> 2Ca + O2
a)
Oxidized
b)
Reduced
14.
What substance is oxidized in the following reaction?
4Fe + 3O2 --> 2Fe2O3
a)
Iron
b)
Fluorine
c)
Oxygen
15.

Oxidation is the _________ of electrons.

a)

loss

b)

gain

c)

sharing

d)

transfer

16.

Reduction is the ___________ of electrons.

a)

loss

b)

gain

c)

sharing

d)

transfer

17.
What substance is oxidized in the following reaction?
4Fe + 3O2 --> 2Fe2O3
a)
Iron
b)
Fluorine
c)
Oxygen
18.
Which statement is true:
Mg → Mg2+ + 2e–
a)
Mg gains 2 electrons
b)
Mg2+ loses 2 electrons
c)
Mg loses 1 electron
d)
Mg loses 2 electrons
19.
Is calcium oxidized or reduced in the following reaction? 
2CaO--> 2Ca + O2
a)
Oxidized
b)
Reduced
20.
Which of the following half reactions correctly represents a reduction half reaction?
a)
Fe →Fe2+ + 2e-
b)
Pb4+ + 2e- →Pb2+
c)
2O-2 →O2 + 4e-
d)
Fe + 3e- →Fe3+
21.
If in a reaction, copper is reduced; its number of electrons has:
a)
Increased
b)
Decreased
c)
Remained Constant
d)
Varies Randomly
22.

Choose all the statements which contain correct definitions of reduction

a)

the removal of oxygen

b)

the removal of hydrogen

c)

the removal of electrons

d)

the decrease in oxidation state

23.

Which one of the following conversions is an example of reduction?

a)

Copper (II) oxide to copper (II) sulfate

b)

Copper (II) oxide to copper

c)

Hydrochloric acid to chlorine

d)

Lead (II) nitrate to lead (II) chloride

24.

Defined as the gain of electrons.

a)

oxidation

b)

redox

c)

reduction

d)

LEO GER

25.

Defined as the loss of electrons.

a)

oxidation

b)

reduction

c)

redox

d)

OIL RIG

26.

Which of the following represents oxidation?

a)

C → CH4

b)

Fe3+ → Fe2+

c)

Cl2 → 2Cl-

d)

Zn → ZnO

27.

Gaining hydrogen is an example of...

a)

oxidation

b)

reduction

28.

Gaining oxygen is an example of...

a)

oxidation

b)

reduction

29.
Which of the following represents reduction?
a)
C →  CO
b)
N2 →  NH3
c)
Zn  →   Zn2+ 
d)
H2 →  H2O
30.

In a redox reaction, spectator ions...

a)

become oxidised

b)

become reduced

c)

remain unchanged

31.

In the half equation:

Cu --> Cu2+ + 2e-

Copper undergoes...

a)

Spectatorship

b)

Reduction

c)

Deprotonation

d)

Oxidation

32.

If the oxidation number of an element reduces in a redox reaction, then this corresponds to the process of...

a)

Reduction

b)

Oxidation

33.
Which are examples of reduction?
a)
I and II
b)
I and III
c)
II and III
d)
I, II and III
34.
Which change does nitrogen undergo oxidation?
a)
A
b)
B
c)
C
d)
D
35.
What happens to Cr3+ ion when it is converted to CrO42–
a)
Oxidation number decreases and it undergo reduction
b)
Oxidation number decreases and it undergo oxidation
c)
Oxidation number increases and it undergo reduction
d)
Oxidation number increases and it undergo oxidation
36.

What is the oxidation number of C in SrCO3?

a)

-4

b)

+2

c)

-6

d)

+4

37.

What is the oxidation number of Cr in Cr2O72- ?

a)

+14

b)

+6

c)

-6

d)

-14

38.
What is oxidation number of H in CaH2?
a)
+1
b)
-1
c)
0
d)
+2
39.

An increase in oxidation number.

a)

more acidic

b)

reduction

c)

less basic

d)

oxidation

40.

The sum of the oxidation numbers in SCN- is equivalent to

a)

0

b)

-1

c)

+1

d)

+3

41.

a compound having +2 oxidation state of O is

a)

H2O

b)

H2O2

c)

OF2

d)

O2F2

42.

When a gas changes iron (III) oxide to iron (II) oxide, it shows that the gas is

a)

a reducing agent

b)

an oxidizing agent

c)

a combustible gas

d)

a diffusible gas

43.

Choose all the statements which are correct for an oxidising agent.

a)

removes hydrogen

b)

gains oxygen

c)

is reduced at the end of the reaction

d)

accepts electrons

44.

In the reaction, Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

a)

carbon monoxide is reduced

b)

carbon monoxide is the oxidising agent

c)

iron(III) oxide is oxidised

d)

iron(III) oxide is the oxidising agent

45.

State the reducing agent in this reaction.

Cu + 4HNO3 -> Cu(NO3)2 + 2H2O + 2NO2

a)

Cu

b)

HNO3

c)

Cu(NO3)2

d)

NO2

46.

Check all the equations whereby the underlined substances has been oxidized.

a)

carbon dioxide + carbon -> carbon monoxide

b)

iron (II) oxide + aluminium -> aluminium oxide + iron

c)

copper (II) oxide + ammonia -> copper + nitrogen + water

d)

hydrogen + oxygen -> water

47.

An increase in oxidation number.

a)

more acidic

b)

reduction

c)

less basic

d)

oxidation

48.

A decrease in oxidation number.

a)

concentrated

b)

reduction

c)

oxidation

d)

dilute

49.

What is the reducing agent here: N2 + 3H2 --> 2NH3

a)

N2

b)

H2

c)

NH3

d)

2NH3

50.

In the reaction

2Ca(s) + O2(g) --> 2CaO(s), calcium is __________

a)

Reduced

b)

Synthesized

c)

Oxidized

d)

None of the above

51.

The sum of the oxidation numbers in Na2CO3 is equivalent to

a)

0

b)

-2

c)

+1

d)

-1

52.
Which statement is true:
Mg → Mg2+ + 2e–
a)
Mg gains 2 electrons
b)
Mg2+ loses 2 electrons
c)
Mg loses 1 electron
d)
Mg loses 2 electrons
53.

What is the oxidation number of chlorine in HClO?

a)

0

b)

-1

c)

+1

d)

+5

54.
What is the species that lose electrons in a redox reaction?
a)
oxidizing agent
b)
reducing agent
c)
is reduced
d)
decreases in oxidation number
55.
What is the species that gain electrons in a redox reaction?
a)
oxidizing agent
b)
reducing agent
c)
is oxidized
d)
increases in oxidation number
56.

What is the oxidizing agent of this reaction?

3Mg + N2−−−−> Mg3N2

a)

Mg

b)

N2

c)

Mg3N2

d)

MgN

57.
What is the reducing agent of this reaction?
3Mg + N2−−−−> Mg3N2
a)
Mg
b)
N2
c)
Mg3N2
d)
MgN
58.
What is the reducing agent of this reaction?
2Al(s) + 6H+(aq) −−−> 2Al3+ (aq) + 3H2(g)
a)
H+
b)
Al3+
c)
Al
d)
H2
59.
What is the oxidizing agent of this reaction?
2Al(s) + 6H+(aq) −−−> 2Al3+ (aq) + 3H2(g)
a)
H2
b)
Al3+
c)
Al
d)
H+
60.

What is the oxidation number of iodine in KIO3?

a)

0

b)

-1

c)

+5

d)

+1

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