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Worksheets

Grade 8 Term3

Total questions: 141

Worksheet time: 2hrs 32mins

Name
Class
Date
1.

What is oxidation reaction?

a)

Reaction where oxygen is gain

b)

Reaction where oxygen is loss

c)

Combustion of carbon

d)

Reactions that involves both gain and loss of oxygen

2.

What is reduction reaction?

a)

Reaction where oxygen is gain

b)

Reaction where oxygen is loss

c)

Decomposition of hydrogen peroxide

d)

Reactions that involves both gain and loss of oxygen

3.

What is redox reaction?

a)

Reaction where oxygen is gain

b)

Reaction where oxygen is loss

c)

Displacement reaction

d)

Reactions that involves both gain and loss of oxygen

4.

The diagram show an example of redox reaction.

Which of the following chemical undergo oxidation?

a)

CuO

b)

H2

c)

Cu

d)

H2O

5.

How do we know hydrogen (H2) undergo oxidation?

a)

It have no oxygen

b)

After the reaction, it gain oxygen

c)

It have oxygen

d)

After the reaction, it lose oxygen

6.

Which of the following chemical undergo reduction?

a)

CuO

b)

H2

c)

Cu

d)

H2O

7.

Reduction is the ___________ of electrons.

a)

loss

b)

gain

c)

transfer

d)

share

8.

Which statement is true:

Mg → Mg2+ + 2e–

a)

Mg gains 2 electrons

b)

Mg2+ loses 2 electron

c)

Mg loses 1 electron

d)

Mg loses 2 electrons

9.

During the process of reduction, _________________

a)

protons are lost.

b)

protons are gained.

c)

electrons are lost.

d)

electrons are gained

e)

neutrons are lost.

10.

Identify the species reduced in the following reaction.


Fe(s) + 2 Ag+(aq) → Fe2+(aq) + 2 Ag(s)

a)

Fe

b)

Ag

c)

none of these

d)

None of the above

11.

The below reaction is an example of _________reaction.

F2 → 2 F- + 2 e-

a)

Oxidation

b)

Reduction

c)

Neutralization

d)

decomposition

e)

combustion

12.

Identify the substance that is reduced in the reaction between copper(II) ion and magnesium.

Cu2+ + Mg → Cu + Mg2+

a)

Cu2+

b)

Mg

c)

Cu

d)

Mg2+

13.
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+
14.

In a reaction, copper is reduced; its number of electrons has:

a)

Increased

b)

Decreased

c)

Remained Constant

d)

Varies Randomly

15.
If an atom loses electrons during a chemical reaction, the atom was:
a)
Oxidized
b)
Reduced
c)
Neutralized
d)
Precipitated
16.
What is the oxidation number of Fe in FeO?
a)
+1
b)
-1
c)
+2
d)
-2
17.
What is oxidation number of P in K3PO4?
a)
+1
b)
+5
c)
-2
d)
0
18.
What is the oxidation number of Ca in Ca3N2?
a)
+3
b)
+2
c)
-3
d)
-2
19.
What is the oxidation number of O in CO2?
a)
+2
b)
-1
c)
+4
d)
-2
20.

Which statement is true of a reducing agent?

a)

It is oxidised as it gains electrons.

b)

It is oxidised as it loses electrons.

c)

It is reduced as it gains electrons.

d)

It is reduced as it loses electrons.

21.

What is the substance that loses hydrogen in a redox reaction?

a)

oxidizing agent

b)

reducing agent

c)

is reduced

d)

decreases in oxidation number

22.

What is the substance that loses oxygen in a redox reaction?

a)

oxidizing agent

b)

reducing agent

c)

is oxidized

d)

increases in oxidation number

23.

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

a)

a combustible gas

b)

a reducing agent

c)

an inert gas

d)

an oxidising agent

24.

What is the colour change of acidified KMnO4(aq) solution as a test for reducing agents?

a)

From green to orange

b)

From orange to green

c)

From purple to colourless

d)

From colourless to purple

25.

What is the oxidizing agent of this reaction?


3Mg + N2 → Mg3N2

a)

Mg

b)

N2

c)

Mg3N2

d)

MgN

26.

What is the reducing agent of this reaction?

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

a)

H+

b)

Al3+

c)

Al

d)

H2

27.

For the following example, identify the reducing agent:

H2 + Cl2 --> 2HCl

a)

H2

b)

Cl2

c)

Both

28.

Which of these will conduct electricity

a)

tap water

b)

distilled water

29.

Conduction of electricity in liquids occurs through electrons.

a)

True

b)

False

30.

When a liquid conducts electricity, a process other than conduction also takes place. What process is this?

a)

electrolysis

b)

electrochemical reaction

c)

electroplating

d)

oxidation

31.

Sugar solution is a good conductor of electricity.

a)

True

b)

False

32.

Which one of the following solutions will not conduct electricity?

a)

lemon juice

b)

vinegar

c)

tap water

d)

vegetable oil

33.
What is electrolysis?
a)
breaking down of a compound using a current
b)
making a compound using a current
34.
Which statement correctly describes the 2 electrodes?
a)
The anode is negative and the cathode is positive
b)
The anode and cathode are both positive
c)
The anode is positive and the cathode is negative
d)
The anode and cathode are both negative.
35.
What is the name given to the solution that is being electrolysed?
a)
Salt solution
b)
Electric solution
c)
Mineral solution
d)
Electrolyte
36.
Explain why the electrolyte has to be a liquid.
a)
So the ions can move
b)
So the electrons can move
c)
So that it doesn't get too hot
d)
So the fish are ok
37.
What happens at the positive electrode?
a)
Positive non-metal ions are attracted
b)
Positive metal ions are attracted
c)
Negative non-metal ions are attracted
d)
Negative metal ions are attracted
38.
Positive ions (cations) will move towards the cathode (-) where they will discharge by....
a)
Breaking apart
b)
Losing electrons
c)
Clumping together.
d)
Gaining electrons
39.
When NaCl solution is electrolysed what has forms at the anode?
a)
Hydrogen
b)
Oxygen
c)
Chlorine
d)
Sodium
40.

___________ electrode is an inert electrode.

a)

Copper

b)

Iron

c)

Carbon

d)

Zinc

41.

Which equation shows what happen to chloride ions at the anode.

a)

Cl- --> Cl + e-

b)

2Cl- --> Cl2 + 2e-

c)

Cl2 - -> 2e- + 2Cl-

d)

Cl2 + 2e- --> 2Cl-

42.

Choose the half-equation that shows the discharge of aluminium ion.

a)

Al3+ - 3e- --> Al

b)

Al2+ + 3e- --> Al

c)

Al3+ + 3e- --> Al

d)

Al3+ --> Al + 3e-

43.

Ionic compounds do not conduct electricity when they are solid because,

a)

their electrons are not free to move

b)

their ions are free to move

c)

their ions are not free to move

d)

their electrons are free to move

44.

What are the ions present in molten Al2O3?

a)

Al2+ and O3-

b)

Al2- and O3+

c)

Al3+ and O2-

d)

Al3- and O2+

45.

Oxidation is loss of electron. Where does oxidation take place during electrolysis.

a)

At anode

b)

In the electrolyte

c)

At the circuit

d)

At cathode

46.

In electrolytic cell that uses aqueous copper(II) sulfate as electrolyte and copper plates as electrodes, what is the product at the anode?

a)

Oxygen gas and water

b)

Copper metal

c)

Copper(II) ions

d)

Hydrogen gas

47.

Anions get discharged by ________ electrons at the ___________

a)

gaining, cathode

b)

losing, anode

c)

gaining, anode

d)

losing, cathode

48.

What is the gas produced at the anode during the electrolysis of very dilute hydrochloric acid?

a)

water

b)

oxygen

c)

hydrogen

d)

chlorine

49.
What is the product formed at the anode during the electrolysis of concentrated copper(II) chloride?
a)
copper
b)
chlorine
c)
hydrogen
d)
oxygen
50.

What is the half-equation for the discharge of hydroxide ions?

a)

2O2- --> O2 + 4e-

b)

OH- --> OH + e

c)

4OH- --> 2H2O + O2 + 4e-

d)

2H2O + O2 + 4e- --> 4OH-

51.

When substance X is electrolysed, the amount of gases P and Q formed is shown.

What is substance X?

a)

concentrated aqueous sodium chloride

b)

concentrated hydrochloric acid

c)

dilute sulfuric acid

d)

molten lead(II) bromide

52.

What are the products at the electrodes when dilute sulfuric acid is electrolysed using inert electrodes?

a)

A

b)

B

c)

C

d)

D

53.

Electricity is passed separately through concentrated hydrochloric acid, concentrated aqueous

sodium chloride and dilute sulfuric acid.

In which rows are the electrolysis products correctly named?

a)

1, 2 and 3

b)

1 and 2 only

c)

1 and 3 only

d)

2 and 3 only

54.

Which row describes the electrolysis of molten potassium bromide?

a)

A

b)

B

c)

C

d)

D

55.

The diagram shows the electrolysis of concentrated hydrochloric acid and concentrated aqueous

sodium chloride using carbon electrodes.

At which electrode(s) is hydrogen produced?

a)

electrode 1 only

b)

electrodes 1 and 3

c)

electrode 2 only

d)

electrodes 2 and 4

56.

What are the electrode products when molten silver iodide is electrolysed between inert electrodes?

a)

A

b)

B

c)

C

d)

D

57.

Copper and hydrogen can each be formed by electrolysis.

At which electrodes are these elements formed?

a)

A

b)

B

c)

C

d)

D

58.

The diagram shows a failed attempt to copper-plate a pan.

Which action will plate the pan with copper?

a)

cooling the copper sulfate solution in an ice bath

b)

heating the copper sulfate solution to boiling point

c)

increasing the voltage from 3V to 6V

d)

making the pan the cathode and the copper the anode

59.

The diagram shows the electroplating of a steel object.

A student made the following statements.

1 The object turns a reddish-brown colour.

2 The copper sulfate solution changes to a paler blue colour.

3 The copper electrode becomes smaller.

Which statements are correct?

a)

1, 2 and 3

b)

1 and 2 only

c)

1 and 3 only

d)

2 and 3 only

60.

An object is electroplated with silver using an aqueous silver salt as the electrolyte.

Which set of conditions is used?ZA

a)

A

b)

B

c)

C

d)

D

61.

The diagram shows an electrolysis experiment.

During the electrolysis, sodium was formed at electrode P and chlorine at electrode Q.

Which choice correctly identifies P, Q and X?

a)

P = anode; Q = cathode; X = concentrated solution of sodium chloride in water

b)

P = anode; Q = cathode; X = molten sodium chloride

c)

P = cathode; Q = anode; X = concentrated solution of sodium chloride in water

d)

P = cathode; Q = anode; X = molten sodium chloride

62.

The diagram shows apparatus for plating a spoon with silver.

Which statement is not correct?

a)

Silver would stick to the spoon because it is a very reactive metal.

b)

The electrolyte would be a silver salt dissolved in water.

c)

The metal electrode would be made from silver..

d)

The spoon would be connected to the negative terminal of the power supply.

63.

Which metal could not be used for electroplating by using an aqueous solution?

a)

chromium

b)

copper

c)

silver

d)

sodium

64.

Which products are formed at the electrodes when a concentrated solution of sodium chloride is electrolysed?

a)

A

b)

B

c)

C

d)

D

65.

A student wishes to electroplate an object with copper.

Which row is correct?

a)

A

b)

B

c)

C

d)

D

66.

Answer the question above

a)

A

b)

B

c)

C

d)

D

67.

Answer the question above

a)

D

b)

A

c)

B

d)

C

68.

Answer the question above

a)

D

b)

A

c)

B

d)

C

69.

Answer the question above

a)

C

b)

D

c)

B

d)

A

70.

Answer the question above

a)

A

b)

B

c)

C

d)

D

71.

Answer the question above

a)

D

b)

C

c)

B

d)

A

72.

The electrode that contains the item to be electroplated

a)

Anode

b)

Cathode

73.

The electrode that contains the plating metal

a)

Anode

b)

Cathode

74.

If you were plating with copper, which electrolyte could be used

a)

Copper sulfate

b)

Nickel sulfate

c)

Hydrochloric acid

d)

Sulfuric acid

75.

If the fork is to be electroplated with silver metal, what electrolyte should be used?

a)

Molten calcium chloride

b)

Aqueous silver nitrate

c)

Sodium chloride solution

d)

Copper(II) sulphate solution

76.

During electrorefining of copper, the impure copper will be

a)

anode

b)

cathode

77.
Which has a bitter taste?
a)
Base
b)
Acid
c)
flagella
d)
cila
78.
Turns litmus red
a)
Acids
b)
Bases
c)
All
79.

Which of the following is not a weak acid

a)

Acetic acid

b)

Oxalic acid

c)

Hydrochloric acid

d)

Formic acid

80.

The bases which are soluble in water is called

a)

Alkali

b)

Strong base

c)

Weak base

d)

Neutral base

81.

When a Universal Indicator is added to sulphuric acid, the solution turns red.

a)

True

b)

False

82.

Indicators are used to test if a solution is ________________

a)

Sweet or Sour

b)

Acidic or Basic

c)

Fresh or Bitter

d)

Sour or Bitter

83.

Acid-Base indicators can tell the difference between an acid or base based on the change in ___________

a)

Smell

b)

Colour

c)

Taste

d)

Feel

84.

Litmus paper changes colour to ___________ in an acid.

a)

Blue

b)

Green

c)

Yellow

d)

Red

85.

Litmus paper changes colour to ___________ in an alkaline.

a)

Blue

b)

Green

c)

Yellow

d)

Red

86.

Phenolphthalein changes colour to ___________ in an acid.

a)

Colourless

b)

Blue

c)

Pink

d)

Yellow

87.

Phenolphthalein changes colour to ___________ in an alkaline.

a)

Colourless

b)

Blue

c)

Pink

d)

Yellow

88.

Methyl Orange changes colour to ___________ in an acid.

a)

Green

b)

Blue

c)

Red

d)

Yellow

89.

Methyl Orange changes colour to ___________ in an alkaline.

a)

Green

b)

Blue

c)

Red

d)

Yellow

90.

Which of the indicators below can tell how acidic or basic a solution is?

a)

Phenolphthalein

b)

Methyl Orange

c)

Universal Indicator

d)

Litmus Paper

91.
The pH scale is a range from:
a)
1-7
b)
0-14
c)
1-14
d)
1-20
92.
A(n) ______ is a substance with a pH less than 7
a)
Acid
b)
Alkaline
c)
Base
d)
Buffer
93.
A(n) _______ is a substance with a pH greater than 7.
a)
Base
b)
Acid
c)
Buffer
d)
Water
94.
What is the only substance with a neutral pH of 7?
a)
Milk
b)
Orange Juice
c)
Water
d)
Blood
95.
Which solution releases H+ in solution?
a)
Base
b)
Acid
c)
Buffer
d)
Water
96.
This substance releases OH- into solution
a)
Acid
b)
Base
c)
Neutral
97.
According to the pH range which substance is more acidic than lemon juice
a)
Hydrochloric acid
b)
cabbage
c)
milk
98.

In a test of pH levels, a baking soda has a pH of 9 and bleach has a pH of 12. What is true about there relationship?

a)

Both of the solution are Bases

b)

Both of the solution are Acids

c)

The Baking soda is an acid and the Bleach is a base

d)

The baking soda is a base and the Bleach is an Acid.

99.

A base is a substance

a)

That releases OH- ions when dissolved in water

b)

That releases H+ ions when dissolved in water

c)

Does not release any ions when dissolved in water

d)

None of the above

100.

Which indicator is colourless in acid and pink in alkali?

a)

Litmus

b)

Phenolphthalein

c)

Universal Indicator

d)

Methyl Orange

101.

What are the products formed when magnesium hydroxide and hydrochloric acid react?

a)

magnesium chloride and hydrogen gas

b)

magnesium chloride and water

c)

hydroxide acid and water

d)

magnesium hydrogenchloride and water

102.

What are the products formed when aluminium hydroxide ad hydrochloric acid react?

a)

magnesium hydroxide and water

b)

aluminium sulphate and water

c)

aluminium chloride and water

d)

aluminium chloride and carbon dioxide gas

103.

What are the products formed when an acid and an alkali react?

a)

salt and water

b)

salt and hydrogen gas

c)

salt and butter

d)

base and water

104.

What is an acid-alkali reaction commonly called?

a)

A disturbing reaction

b)

An explosive reaction

c)

A neutralisation reaction

d)

A simple reaction

105.

What are the products formed when copper hydroxide and hydrochloric acid react?

a)

copper nitrate and water

b)

copper chloride and water

c)

copper chlorine and carbon dioxide gas

d)

copper sulphate and water

106.

What are the products formed when lead hydroxide and sulphuric acid react?

a)

sulphate hydroxide and water

b)

lead nitrate and water

c)

magnesium sulphate and water

d)

lead sulphate and water

107.
An acid reacts with metal to produce 
a)
Carbon dioxide 
b)
Hydrogen gas
c)
Hydrogen gas and water 
d)
Salt and hydrogen gas 
108.
An acid reacts with a metal carbonate to produce 
a)
Salt, water and hydrogen gas
b)
Salt, water and carbon dioxide
c)
Limewater
d)
Salt and water 
109.

When carbonates react with acids, which gas is produced?

a)

Hydrogen

b)

Carbon dioxide

c)

Oxygen

d)

Nitrogen

110.
Complete the following reaction:
Sulphuric acid + sodium carbonate
--> 
a)
Carbon dioxide + water 
b)
calcium carbonate + water + carbon dioxide 
c)
Sodium sulphate + water + carbon dioxide 
d)
Sodium chloride + water + carbon dioxide 
111.

Which of the following is a strong base?

a)

A. Cacium hydroxide

b)

B. Sodium hydroxide

c)

C. Sodium carbonate

d)

D. Ammonium hydroxide

112.

Which word matches this definition "a molecule or other species which can donate a proton (H+) or accept an electron pair in reactions"?

a)

Base

b)

Alkali

c)

Acid

d)

Amphoteric

113.

Which word matches this definition "a molecule or other species which can accept a proton or donate an electron pair in reactions"?

a)

Base

b)

Alkali

c)

Acid

d)

Amphoteric

114.

H+ (aq) + OH- (aq) --> H2O (l)


This ionic equation represents what process/reaction?

a)

Combustiion - Acid and an Alkali

b)

Neutralisation - Acid and an Alkali

c)

Neutralisation - Acid and a solid base

d)

Neutralisation - Base and an Alkali

115.

What type of oxide is:

Copper (II) Oxide

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

116.

What type of oxide is:

Carbon monoxide

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

117.

What type of oxide is:

Carbon Dioxide

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

118.

Amphoteric oxides are substances that

a)

Reacts with acids only

b)

Reacts with bases only

c)

Reacts with acids and bases

d)

Do not react with acids or bases

119.

ZnO is an oxide that can react with acids and bases, as shown in the following equations:

ZnO + HSO --> ZnSO + H2O

ZnO +2NaOH -->Na2ZnO2 +H2O


What name is given to an oxide that reacts with both acids and bases?

a)

neutral

b)

acidic

c)

precipitate

d)

amphoteric

e)

displacement

120.

Which of the following oxides is most likely to be an basic oxide?

a)

Al2O3

b)

H2O

c)

MgO

d)

CO2

121.

What type of oxide is:

Water

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

122.

What type of oxide is:

Potassium oxide

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

123.

What type of oxide is:

Nitrogen Dioxide

a)

Amphoteric Oxide

b)

Basic Oxide

c)

Neutral Oxide

d)

Acidic Oxide

124.

What does the word insoluble mean?

a)

Does dissolve

b)

Doesn't dissolve

c)

Is part of a solid

125.

Complete the following word equation:

Metalcarbonate + acid -->

a)

Salt + Hydrogen

b)

Salt + Water + Carbon Dioxide

c)

Salt + Water

126.

What are the products formed when magnesium hydroxide and hydrochloric acid react?

a)

magnesium chloride and hydrogen gas

b)

magnesium chloride and water

c)

hydroxide acid and water

d)

magnesium hydrogenchloride and water

127.

How do you remove the water to leave solid copper sulfate crystals?

a)

Filter

b)

Evaporate

c)

Distill

128.

Filtration is used to separate a ______ from a liquid.

a)

undissolved solid

b)

dissolved solid

c)

dissolved gas

d)

undissolved gas

129.

Complete the following word equation:

Metal + Acid -->

a)

salt + water

b)

salt + hydrogen

c)

salt + Water + Carbon dioxide

d)

salt + water + hydrogen

130.

Which of the following is a hydrated salt?

a)

Baking soda

b)

Washing soda

c)

Bleaching powder

d)

Caustic soda

131.

What is the colour of anhydrous copper sulphate?

a)

Blue

b)

Green

c)

White

d)

bluish green

132.

What type of reaction produced an insoluble salt?

a)

Neutralisation reaction

b)

Precipitation reaction

c)

Titration reaction

d)

Insoluble reaction

133.

When a soluble salt is formed from an acid and an insoluble base, how do you know when an excess of a base has been added?

a)

When bubbles of gas appear

b)

When the reactant all dissolves

c)

When some of the reactant is left unreacted/undissolved

d)

When a colour change happens

134.

Why do you add excess of the insoluble reactant when making a soluble salt?

a)

To make sure all the acid is used up

b)

To separate the solid from the solution

c)

To make sure a reaction occurs

d)

To have the reaction happen faster

135.

How do you separate an excess insoluble reactant from a solution?

a)

Filtration

b)

Precipitation

c)

Crystalisation

d)

Evaporation

136.

When producing a soluble salt in a reaction between an acid and an alkali, how can you prepare dry solid crystals from the solution?

a)

Filtration

b)

Neutralisation

c)

Condensation

d)

Evaporation/crystallisation

137.

What is the purpose of a titration when making pure salts?

a)

To test if reactants react.

b)

To determine the exact quantities needed for neutralisation

c)

To calculate the concentration of the salt

d)

To test quality of reactants.

138.
Salts that are made with hydrochloric acid are called ______________.
a)
chlorides
b)
sulfates
c)
nitrates
d)
carbonates
139.
Salts that are made with nitric acid are called ______________.
a)
chlorides
b)
sulfates
c)
nitrates
d)
carbonates
140.
What salt is produced if you react sodium hydroxide with hydrochloric acid?
a)
sodium hydroxide
b)
sodium sulfate
c)
sodium nitrate
d)
sodium chloride
141.

pH is the measure of the concentration of ______.

a)

Acids

b)

H+ ion

c)

OH- ion

d)

Bases

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