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Cambridge IGCSE™

*6609476142*

CHEMISTRY0620/32
May/June 2023

Paper 3 Theory (Core)

1 hour 15 minutes


You must answer on the question paper.
No additional materials are needed.

INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● You may use a calculator.
● You should show all your working and use appropriate units.

INFORMATION
● The total mark for this paper is 80.
● The number of marks for each question or part question is shown in brackets [ ].
● The Periodic Table is printed in the question paper.

This document has 20 pages. Any blank pages are indicated.

IB23 06_0620_32/3RP
© UCLES 2023

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2
1Fig. 1.1 shows part of the Periodic Table.
I

II

III IV

V

VI VII VIII
He

C

N

O

Ne
Cl

K Ca

Cr

Cu Zn

Br
I

Sr
Fig. 1.1
Answer the following questions using only the elements in Fig. 1.1.
Each symbol of the element may be used once, more than once or not at all.
Give the symbol of the element that:












(a)forms 21% by volume of clean, dry air
............................................................................................................................................... [1]
(b)has an atom with only three occupied electron shells
............................................................................................................................................... [1]
(c)has an atom with only one electron in its outer shell
............................................................................................................................................... [1]

(d)is a grey-black solid at room temperature
............................................................................................................................................... [1]
(e)forms an ion that gives a green precipitate on addition of aqueous ammonia
............................................................................................................................................... [1]
(f)is used in electrical wiring because of its good ductility.



............................................................................................................................................... [1]



[Total: 6]

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3
2

(a)Table 2.1 shows some properties of the halogens.
Table 2.1

halogen

melting point
in °C

boiling point
in °C

density at room
temperature and
pressure in g / cm3

chlorine

–101

–35

0.003

bromine

–7

+59

3.12

iodine

+114

astatine

+302

4.93
+337

Use the information in Table 2.1 to predict:


(i)the boiling point of iodine ���������������������������������������������������������������������������������������������� [1]



(ii)the density of astatine at room temperature and pressure ������������������������������������������� [1]



(iii)the physical state of bromine at +50 °C. Give a reason for your answer.



physical state .......................................................................................................................

reason ..................................................................................................................................

..............................................................................................................................................
[2]



(b)Aqueous bromine reacts with aqueous potassium iodide.
(i)Complete the word equation for this reaction.

bromine

+

potassium
iodide

→

........................

+

........................
........................

[2]


(ii)Explain why aqueous iodine does not react with aqueous potassium bromide.




........................................................................................................................................ [1]
(iii)Describe a test for iodide ions.

test .......................................................................................................................................
observations ........................................................................................................................

[2]


© UCLES 2023

[Total: 9]

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4
3(a)Water from natural sources can contain metal compounds and phosphates.


(i)Name two other substances found in water which are harmful to aquatic life.

1 ...........................................................................................................................................
2 ...........................................................................................................................................
[2]


(ii)State why phosphates are harmful to aquatic life.




........................................................................................................................................ [1]
(b)Table 3.1 shows the masses of ions, in mg, present in a 1000 cm3 sample of polluted water.

Table 3.1
formula
of ion

mass of ion present
in mg / 1000 cm3 of
polluted water

ammonium

NH4+

0.5

calcium

Ca2+

1.8

chloride

Cl –

2.0

copper(II)

Cu2+

0.3

HCO3–

8.0

Mg2+

1.6

NO3–

0.6

K+

8.3

silicate

SiO32–

5.0

sodium

Na+

5.2

sulfate

SO42–

0.2

name of ion

hydrogencarbonate
magnesium
potassium

Answer these questions using information from Table 3.1.


(i)Name the positive ion present in the highest concentration.




........................................................................................................................................ [1]
(ii)State the name of the NO3– ion.




........................................................................................................................................ [1]
(iii)Calculate the mass of magnesium ions present in 250 cm3 of polluted water.



© UCLES 2023

mass = .............................. mg [1]
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5


(c)Water is produced when blue copper(II) sulfate is heated.
CuSO4•5H2O(s)





+

5H2O(l)

blue copper(II)
white copper(II)
sulfatesulfate

(i)Describe how white copper(II) sulfate can be changed to blue copper(II) sulfate.




CuSO4(s)

........................................................................................................................................ [1]
(ii)Choose a word from the list which best describes white copper(II) sulfate.

Draw a circle around your chosen answer.
anhydrous




aqueous

hydrated

oxidised[1]

(d)Complete the symbol equation for the reaction of calcium with water.



Ca + ......H2O → Ca(OH)2 + ..............



© UCLES 2023

[2]
[Total: 10]

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6
4This question is about chlorine and compounds of chlorine.


(a)Chlorine has diatomic molecules.



Define the term diatomic.



............................................................................................................................................... [1]



(b)Deduce the number of protons, neutrons and electrons in the chloride ion shown.
37
–
17Cl



number of protons ......................................................................................................................

number of neutrons ....................................................................................................................


number of electrons ....................................................................................................................
[3]



(c)Chlorine reacts with hydrogen to produce hydrogen chloride. The reaction is exothermic.
(i)State the meaning of the term exothermic.



..............................................................................................................................................



........................................................................................................................................ [2]



(ii)Fig. 4.1 shows an incomplete reaction pathway diagram for the reaction of chlorine with
hydrogen.

energy

progress of reaction
Fig. 4.1
Complete Fig. 4.1 by writing these formulae on the diagram:

● Cl 2 + H2
● 2HCl.[1]


(iii)Explain how Fig. 4.1 shows that the reaction is exothermic.



..............................................................................................................................................



........................................................................................................................................ [1]

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7


(d)A few drops of methyl orange indicator are added to dilute hydrochloric acid.

State the colour of the solution.


............................................................................................................................................... [1]

(e)Dilute hydrochloric acid reacts with sodium hydroxide.



(i)Complete the word equation for this reaction.
hydrochloric
acid

+

sodium
hydroxide

→

........................

+

........................

........................

[2]


(ii)Sodium hydroxide is an alkali.

Write the formula of the ion present in all alkalis.

© UCLES 2023

........................................................................................................................................ [1]

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8


(f)Fig. 4.2 shows the apparatus used for the electrolysis of concentrated aqueous sodium chloride
using graphite electrodes.
+ power –
supply

Fig. 4.2




(i)Label Fig. 4.2 to show:
● the anode
● the electrolyte.

[2]

(ii)Name the products and state the observations at the positive and negative electrodes.

product at the positive electrode


..............................................................................................................................................

observations at the positive electrode


..............................................................................................................................................

product at the negative electrode


..............................................................................................................................................

observations at the negative electrode

..............................................................................................................................................
[4]


© UCLES 2023

[Total: 18]

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9
5

This question is about metals.



(a)Carbon is used to extract iron from iron ore in a blast furnace.



(i)Name the main ore of iron.




........................................................................................................................................ [1]
(ii)Iron(III) oxide in the iron ore is reduced by carbon monoxide.

Name the two substances which react in the blast furnace to produce carbon monoxide.



................................................................ and ��������������������������������������������������������������� [2]
(b)Iron rusts in the presence of oxygen and water.

State one method of preventing rusting.

............................................................................................................................................... [1]
(c)Table 5.1 shows some information about the reaction of four metals with steam.
Table 5.1
metal

reaction with steam when metal is cold

beryllium

reacts slowly

chromium

reacts slowly only when the metal is very hot

magnesium

reacts rapidly

silver

no reaction

Put the four metals in order of their reactivity.

Put the least reactive metal first.
least reactive

most reactive

[2]


© UCLES 2023

[Total: 6]

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10
6


(a) A
 student investigates the reaction of different-sized pieces of calcium carbonate with dilute
hydrochloric acid.
 he sizes of the pieces of calcium carbonate are:
T
● large
● medium
● small.

All other conditions stay the same.


Table 6.1 shows the time taken for each reaction to finish.
Table 6.1

size of pieces of
calcium carbonate

time taken for the
reaction to finish / s
160
50
450



(i) C
 omplete Table  6.1 by writing the sizes of the pieces of calcium  carbonate in the first
column.[1]



(ii) D
 escribe the effect on the time taken for small pieces of calcium carbonate to finish reacting
with dilute hydrochloric acid when the temperature is increased.

All other conditions stay the same.


........................................................................................................................................ [1]



(iii) D
 escribe the effect on the time taken for small pieces of calcium carbonate to finish reacting

with dilute hydrochloric acid when the concentration of hydrochloric acid is decreased.



All other conditions stay the same.



........................................................................................................................................ [1]



(b)Crystals of calcium chloride can be prepared by reacting excess calcium carbonate with dilute
hydrochloric acid.

Name the process used to separate the unreacted calcium carbonate from the rest of the
reaction mixture.


............................................................................................................................................... [1]

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11


(c)Calcium carbonate is insoluble in water.

Choose one other compound that is insoluble in water.
Tick (✓) one box.


ammonium sulfate



potassium nitrate



silver chloride


sodium hydroxide
[1]


© UCLES 2023

[Total: 5]

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12

7

(a)Fig. 7.1 shows the displayed formula of compound D.
O
H

O

C

H
O

C

H

C

H

C

O

H

O

H

C

Fig. 7.1


(i)On Fig. 7.1 draw a circle around the alcohol functional group.



(ii)Deduce the molecular formula of compound D.




........................................................................................................................................ [1]
(iii)Explain, by referring to the structure in Fig. 7.1, why compound D is unsaturated.





[1]

........................................................................................................................................ [1]
(b)Ethene is also an unsaturated compound.
(i)Draw the displayed formula of ethene.

[1]

(ii)Describe a test for unsaturated compounds.

test .......................................................................................................................................
observations ........................................................................................................................
[2]

© UCLES 2023

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13



(c)Ethene can be manufactured by cracking larger alkane molecules.
(i)State two conditions for cracking.

1 ...........................................................................................................................................
2 ...........................................................................................................................................
[2]


(ii)Complete the symbol equation for the cracking of decane, C10H22, to produce ethene and
one other hydrocarbon.

C10H22 → C2H4 + ................

[1]

(d)Ethanol can be manufactured by the reaction of ethene with steam.

Name one other method of manufacturing ethanol.



............................................................................................................................................... [1]
(e)Ethanol can be oxidised to ethanoic acid.

Ethanoic acid reacts with sodium.
Name the salt formed when ethanoic acid reacts with sodium.


............................................................................................................................................... [1]


(f)Ethanoic acid reacts with propanol.
The organic product has the molecular formula C5H10O2.
Complete Table 7.1 to calculate the relative molecular mass of C5H10O2.
Table 7.1
atom

number of atoms

relative
atomic mass

carbon

12

hydrogen

1

oxygen

2

16

2 × 16 = 32



relative molecular mass = .............................. [2]



[Total: 13]

© UCLES 2023

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14
8

This question is about non-metals and compounds of non-metals.



(a)Describe two physical properties which are typical of non-metals.

1 ..................................................................................................................................................
2 ..................................................................................................................................................
[2]



(b)Methane is a compound of carbon and hydrogen.
(i)Complete Fig. 8.1 to show the dot-and-cross diagram for a molecule of methane.

Show outer shell electrons only.

H

H

C

H

H

Fig. 8.1
[1]


(ii)Methane is an alkane.

Write the general formula for alkanes.



........................................................................................................................................ [1]
(iii)Methane is an air pollutant.

State one source of methane in the air.



........................................................................................................................................ [1]
(iv)State one adverse effect of methane in the air.



........................................................................................................................................ [1]



(v)Carbon particulates and water are two of the products of the incomplete combustion of
methane.

Name one other compound formed during the incomplete combustion of methane.

© UCLES 2023

........................................................................................................................................ [1]
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15



(c)Sulfur dioxide is an air pollutant which contributes to acid rain.
(i)Choose from the list the pH value that is acidic.

Draw a circle around your chosen answer.
pH 4




pH 7

pH 9

pH 13[1]

(ii)State two methods of reducing acid rain.

1 ...........................................................................................................................................
2 ...........................................................................................................................................

[2]


(iii) S
 ulfur  dioxide gas turns aqueous acidified potassium  manganate(VII) from purple to
colourless.

Fig. 8.2 shows a gas jar of sulfur dioxide separated from a gas jar of air by a glass plate.
A piece of filter paper soaked in aqueous acidified potassium manganate(VII) is glued to
the top of the gas jar of air.

air

filter paper soaked
in aqueous acidified
potassium manganate(VII)
glass plate

sulfur dioxide

glass plate present

a short time after the
glass plate is removed
Fig. 8.2

The glass plate is removed.

At first, the filter paper remains purple.

After a short time, the filter paper turns colourless.
Explain these results in terms of the kinetic particle theory.


..............................................................................................................................................



..............................................................................................................................................



..............................................................................................................................................



..............................................................................................................................................



........................................................................................................................................ [3]



[Total: 13]

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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.
Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge
Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.

© UCLES 2023

0620/32/M/J/23


© UCLES 2023

12

V

Cr

Mn

Co

27

Ni

28

Cu

29

Zn

30

Fe

57–71

56

55

0620/32/M/J/23

104

88

–

90

89

232

thorium

actinium

–

Th

Ac

140

cerium

139

lanthanum

59

231

protactinium

Pa

91

141

praseodymium

Pr

–

58

Ce

–

Db

dubnium

Rf

rutherfordium

La

57

actinoids

105

181

tantalum

Ta

73

93

niobium

Nb

41

51

vanadium

238

uranium

U

92

144

neodymium

60

Nd

–

Sg
seaborgium

106

184

tungsten

W

74

96

molybdenum

Mo

42

52

chromium

–

neptunium

Np

93

–

promethium

61

Pm

–

Bh
bohrium

107

186

rhenium

Re

75

–

technetium

Tc

43

55

manganese

–

plutonium

Pu

94

150

samarium

62

Sm

–

Hs
hassium

108

190

osmium

Os

76

101

ruthenium

Ru

44

56

iron

–

americium

Am

95

152

europium

63

Eu

–

Mt
meitnerium

109

192

iridium

Ir

77

103

rhodium

Rh

45

59

cobalt

–

curium

Cm

96

157

gadolinium

64

Gd

–

Ds
darmstadtium

110

195

platinum

Pt

78

106

palladium

Pd

46

59

nickel

The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).

actinoids

lanthanoids

–

Ra

radium

Fr

francium

89–103

178

87

137

hafnium

133

barium

Hf

caesium

lanthanoids

Ba

72

91

zirconium

Zr

40

48

titanium

Cs

89

yttrium

88

strontium

85

rubidium

Y

39

45

Sr

38

40

Ca

Rb

37

39

K

scandium

–

berkelium

Bk

97

159

terbium

65

Tb

–

Rg
roentgenium

111

gold

197

Au

79

108

silver

Ag

47

64

copper

–

californium

Cf

98

163

dysprosium

66

Dy

–

Cn
copernicium

112

201

mercury

Hg

80

112

cadmium

Cd

48

65

zinc

calcium

Ti

26

potassium

Sc

25

31

24

–

einsteinium

Es

99

165

holmium

67

Ho

–

Nh
nihonium

113

204

thallium

Tl

81

115

indium

In

49

70

gallium

Ga

27

20

24

19

23

aluminium

Al

13

11

boron

magnesium

23

1

sodium

22

B

C

N

7

O

8

VI

F

9

VII

2

VIII

–

fermium

Fm

100

167

erbium

68

Er

–

Fl

flerovium

114

lead

207

Pb

82

tin

119

Sn

50

73

germanium

Ge

32

28

silicon

Si

14

12

carbon

–

mendelevium

Md

101

169

thulium

69

Tm

–

Mc
moscovium

115

209

bismuth

Bi

83

122

antimony

Sb

51

75

arsenic

As

33

31

phosphorus

P

15

14

nitrogen

–

nobelium

No

102

173

ytterbium

70

Yb

–

Lv
livermorium

116

–

polonium

Po

84

128

tellurium

Te

52

79

selenium

Se

34

32

sulfur

S

16

16

oxygen

–

Lr

lawrencium

103

175

lutetium

71

Lu

–

Ts
tennessine

117

–

astatine

At

85

127

iodine

I

53

80

bromine

Br

35

35.5

chlorine

Cl

17

19

fluorine

–

oganesson

Og

–

118

radon

86

Rn

131

xenon

54

Xe

84

krypton

36

Kr

40

argon

18

Ar

20

neon

Ne

10

4

helium

6

V

hydrogen

5

IV

He

Mg

21

relative atomic mass

name

atomic symbol

atomic number

Key

III

H

1

Na

9

11

7

Be

beryllium

Li

4

3

lithium

II

I

Group

The Periodic Table of Elements

20


Cambridge IGCSE™
CHEMISTRY

0620/32

Paper 3 Theory (Core)

May/June 2023

MARK SCHEME
Maximum Mark: 80

Published

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the May/June 2023 series for most

Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some
Cambridge O Level components.

This document consists of 11 printed pages.
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0620/32

Cambridge IGCSE – Mark Scheme
PUBLISHED
Generic Marking Principles

May/June 2023

These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the
specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these
marking principles.
GENERIC MARKING PRINCIPLE 1:
Marks must be awarded in line with:




the specific content of the mark scheme or the generic level descriptors for the question
the specific skills defined in the mark scheme or in the generic level descriptors for the question
the standard of response required by a candidate as exemplified by the standardisation scripts.

GENERIC MARKING PRINCIPLE 2:
Marks awarded are always whole marks (not half marks, or other fractions).
GENERIC MARKING PRINCIPLE 3:
Marks must be awarded positively:






marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond
the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate
marks are awarded when candidates clearly demonstrate what they know and can do
marks are not deducted for errors
marks are not deducted for omissions
answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the
question as indicated by the mark scheme. The meaning, however, should be unambiguous.

GENERIC MARKING PRINCIPLE 4:
Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level
descriptors.

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0620/32

Cambridge IGCSE – Mark Scheme

PUBLISHED

May/June 2023

GENERIC MARKING PRINCIPLE 5:
Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may
be limited according to the quality of the candidate responses seen).
GENERIC MARKING PRINCIPLE 6:
Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or
grade descriptors in mind.

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0620/32

Cambridge IGCSE – Mark Scheme
PUBLISHED

May/June 2023

Science-Specific Marking Principles
1

Examiners should consider the context and scientific use of any keywords when awarding marks. Although keywords may be present, marks
should not be awarded if the keywords are used incorrectly.

2

The examiner should not choose between contradictory statements given in the same question part, and credit should not be awarded for
any correct statement that is contradicted within the same question part. Wrong science that is irrelevant to the question should be ignored.

3

Although spellings do not have to be correct, spellings of syllabus terms must allow for clear and unambiguous separation from other
syllabus terms with which they may be confused (e.g. ethane / ethene, glucagon / glycogen, refraction / reflection).

4

The error carried forward (ecf) principle should be applied, where appropriate. If an incorrect answer is subsequently used in a scientifically
correct way, the candidate should be awarded these subsequent marking points. Further guidance will be included in the mark scheme
where necessary and any exceptions to this general principle will be noted.

5

‘List rule’ guidance
For questions that require n responses (e.g. State two reasons …):






The response should be read as continuous prose, even when numbered answer spaces are provided.
Any response marked ignore in the mark scheme should not count towards n.
Incorrect responses should not be awarded credit but will still count towards n.
Read the entire response to check for any responses that contradict those that would otherwise be credited. Credit should not be
awarded for any responses that are contradicted within the rest of the response. Where two responses contradict one another, this

should be treated as a single incorrect response.
Non-contradictory responses after the first n responses may be ignored even if they include incorrect science.

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0620/32
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Cambridge IGCSE – Mark Scheme
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May/June 2023

Calculation specific guidance
Correct answers to calculations should be given full credit even if there is no working or incorrect working, unless the question states ‘show
your working’.
For questions in which the number of significant figures required is not stated, credit should be awarded for correct answers when rounded
by the examiner to the number of significant figures given in the mark scheme. This may not apply to measured values.
For answers given in standard form (e.g. a  10n) in which the convention of restricting the value of the coefficient (a) to a value between 1
and 10 is not followed, credit may still be awarded if the answer can be converted to the answer given in the mark scheme.
Unless a separate mark is given for a unit, a missing or incorrect unit will normally mean that the final calculation mark is not awarded.
Exceptions to this general principle will be noted in the mark scheme.

7

Guidance for chemical equations
Multiples / fractions of coefficients used in chemical equations are acceptable unless stated otherwise in the mark scheme.

State symbols given in an equation should be ignored unless asked for in the question or stated otherwise in the mark scheme.

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