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Practice Oxidation Number & Oxidizing/Reducing Agents

Total questions: 41

Worksheet time: 22mins

Name
Class
Date
1.

In redox reactions, what happens to the reducing agent?

a)

It is oxidised

b)

It does not participate in the reaction and remains unchanged

c)

It is reduced

2.

Of the following, which would most likely be an oxidizing agent?

(The most likely to be reduced.)

a)

K

b)

Ag+

c)

Cl-

3.

For the following example, identify the reducing agent:

(The reactant that is oxidized.)

H2 + Cl2 --> 2HCl

a)

H2

b)

Cl2

c)

Both

4.

What is the oxidizing agent of this reaction?

(The reactant that is reduced.)

3Mg + N2−−−−> Mg3N2

a)

Mg

b)

N2

c)

Mg3N2

d)

MgN

5.

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

6.

What is the reducing agent of this reaction?

(The reactant that is oxidized.)

2Al(s) + 6H+(aq) −−−> 2Al3+ (aq) + 3H2(g)

a)

H+

b)

Al3+

c)

Al

d)

H2

7.

Reduction is the ___________ of electrons.

a)

loss

b)

gain

c)

transfer

d)

share

8.

What is the oxidation number of iodine in KIO3?

a)

5

b)

1

c)

0

d)

-1

9.

Determine the oxidation number of chromium in CrO42-.

a)

5

b)

6

c)

4

d)

2

10.

A decrease in oxidation number.

a)

oxidation

b)

combination

c)

reduction

11.

Substance that oxidizes another substance by accepting its electrons.

a)

oxidizing agent

b)

reducing agent

c)

combustion

12.

In a redox reaction, the species reduced

a)

gains electrons and is the oxidizing agent

b)

loses electrons and is the oxidizing agent

c)

gains electrons and is the reducing agen

d)

loses electrons and is the reducing agent

13.

What is the oxidation number assigned to manganese in KMnO4?

a)

7

b)

5

c)

4

d)

0

14.

In which substance does sulfur have a negative oxidation number?

a)

Na2S

b)

SO2

c)

S

15.

The oxidation number of Hydrogen in KH potassium hydride equals:

a)

-1

b)

+1

c)

0

d)

2

16.

What is the oxidation number of chlorine in ClO3- ?

a)

5

b)

1

c)

0

d)

2

17.

An aqueous solution of potassium iodide turns from colourless to brown due to the formation of the iodine molecule. What happens to the iodide ions?

a)

Iodide ions are oxidised due to gain of electrons.

b)

Iodide ions are oxidised due to loss of electrons.

c)

Iodide ions are reduced due to loss of electrons.

d)

Iodide ions are reduced due to gain of electrons.

18.
What is the oxidation number of Fe in FeO?
a)
+1
b)
-1
c)
+2
d)
-2
19.
What is the oxidation number of O in CO2?
a)
+2
b)
-1
c)
+4
d)
-2
20.
The sum of all oxidation numbers in a neutral compound is ___.
a)
0
b)
1
c)
-1
d)
depends on the compound
21.
What is oxidation number of Mn in MnO2 ?
a)
0
b)
+2
c)
-2
d)
+4
22.
What is the oxidation number of Ca in Ca3N2?
a)
+3
b)
+2
c)
-3
d)
-2
23.
What is the oxidation number of S in SO4 2-  ?
a)
-2
b)
+2
c)
+6
d)
-4
24.
What is oxidation number of Cr in
Cr2O72-?
a)
-2
b)
+2
c)
+6
d)
+12
25.

What is the oxidation state of Cl in ClO- ?

a)

0

b)

+1

c)

-1

d)

+2

26.

What is the oxidation state of Cu in Cu2+?

a)

-1

b)

-2

c)

+2

d)

0

27.

What is the oxidation state of H in H2?

a)

+2

b)

+1

c)

0

d)

None of the above

28.

S in HSO4- ?

a)

+5

b)

-6

c)

+6

d)

+2

29.
What is oxidation number of H in H2O?
a)
0
b)
-2
c)
-1
d)
+1
30.

Which substance is oxidized in the following reaction?

H2O + H3AsO3 + I2 ---> H3AsO4 + 2HI

a)

H3AsO3

b)

I2

c)

H2O

d)

HI

31.

Which substance is reduced in the following equation?

16HNO3 + 2KTcO4 + 3Sn(NO3)2 ---> 2Tc(NO3)4 + 3Sn(NO3)4 + 8H2O + 2KNO3

a)

KTcO4

b)

Sn(NO3)2

c)

HNO3

d)

KNO3

32.

Which substance is the oxidizing agent (i.e., the reactant that is reduced)?

8HNO3 + H3AsO4 + 4Zn ---> AsH3 + 4Zn(NO3)2 + 4H2O

a)

Zn

b)

H3AsO4

c)

HNO3

d)

H2O

33.

Which substance is reduced in the following reaction?

KCl + 5HCl + K2Cr2O7 + 3SO2 ---> 2CrCl3 + 3KHSO4 + H2O

a)

SO2

b)

K2Cr2O7

c)

HCl

d)

KCl

34.

Which of the following is the oxidizing agent for this reaction?

24H2S + 16HNO3 ---> 3S8 + 16NO + 32H2O

a)

H2S

b)

HNO3

c)

S8

d)

H2O

35.
What is the oxidation number of N in NO21- ?
a)
-3
b)
+4
c)
-2
d)
+3
36.
What is oxidation number of P in K3PO4?
a)
+1
b)
+5
c)
-2
d)
0
37.

Give the oxidation number of Nitrogen and Oxygen in N2O molecule.

a)

Nitrogen +1, Oxygen -2

b)

Nitrogen -1, Oxygen -2

c)

Nitrogen +2, Oxygen -2

d)

Nitrogen -3, Oxygen -2

38.

Give the oxidation number of all elements in sulfur dioxide, SO2 molecule.

a)

S-2 and O-2

b)

S+4 and O-2

c)

S-4 and O-2

d)

S-2 and O-1

39.

Give the oxidation number for the underlined atoms below.

a)

+4

b)

-3

c)

-4

d)

0

40.

Give the oxidation number for antimony in the ION pictured. (NOTE: the charge on the ion!)

a)

+6

b)

+5

c)

+4

d)

+3

41.

Determine the oxidation number of the NITROGEN atom.

a)

+2

b)

-3

c)

+4

d)

-5

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