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Cambridge IGCSE™

*6863939729*

CHEMISTRY0620/33
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_33/2RP
© UCLES 2023

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

II

III IV

V

VI VII VIII

C

N

O

Li

F

Al
Ca

Cr

Fe

Cu

Ar
Br
I

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)is present in diamond
............................................................................................................................................... [1]
(b)forms an oxide that contributes to acid rain

............................................................................................................................................... [1]
(c) has an atom with five occupied electron shells
............................................................................................................................................... [1]
(d)forms an ion with a charge of 1+
............................................................................................................................................... [1]
(e)forms an ion that gives a red-brown precipitate on addition of aqueous ammonia
............................................................................................................................................... [1]
(f)is used in the manufacture of aircraft because of its low density.



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



[Total: 6]

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3
2

(a)Table 2.1 shows some properties of the halogens.
Table 2.1
density at room
temperature and
pressure in g / cm3

halogen

melting point
in °C

boiling point
in °C

fluorine

–220

–188

chlorine

–101

bromine

–7

+59

3.12

+114

+184

4.93

iodine

0.003

Use the information in Table 2.1 to predict:


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



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



(iii)the physical state of iodine at +100 °C. Give a reason for your answer.



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

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

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

(b)Aqueous chlorine reacts with aqueous sodium bromide.
(i)Complete the word equation for this reaction.

chlorine

+

sodium
bromide

→

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

+

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

[2]


(ii)State a test for sodium ions.

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


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[Total: 8]

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4
3(a)Polluted water can contain harmful substances such as metal compounds, nitrates and sewage.


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

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


(ii)State why sewage can cause disease.




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

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

ammonium

NH4+

1.2

calcium

Ca2+

2.2

chloride

Cl –

2.5

HCO3–

13.0

magnesium

Mg2+

1.0

nickel(II)

Ni2+

0.2

nitrate

NO3–

0.4

K+

6.3

silicate

SiO32–

8.0

sodium

Na+

12.2

SO42–

0.1

name of ion

hydrogencarbonate

potassium

Answer these questions using information from Table 3.1.


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




........................................................................................................................................ [1]
(ii)State the name of the ion SO42–.




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


© UCLES 2023

mass = .............................. mg [1]
0620/33/M/J/23


5


(c)Cobalt(II) chloride can be used to test for the presence of water.
CoCl 2(s) + 6H2O(l)





blue cobalt(II)
pink cobalt(II)
chloridechloride

(i)Describe how pink cobalt(II) chloride can be changed to blue cobalt(II) chloride.




CoCl 2•6H2O(s)

........................................................................................................................................ [1]
(ii)Choose a word from the list which best describes pink cobalt(II) chloride.

Draw a circle around your chosen answer.

anhydrous




hydrated

liquid

reduced[1]

(d)Iron reacts with steam to form Fe3O4 and a gas which pops with a lighted splint.

Complete the symbol equation for this reaction.


3Fe + ......H2O → Fe3O4 + 4......



© UCLES 2023

[2]
[Total: 10]

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


(a)Deduce the number of protons, neutrons and electrons in the bromide ion shown.
81
–
35Br



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



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


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


(b)Hydrogen bromide decomposes to hydrogen and bromine when heated.

Fig. 4.1 shows an incomplete reaction pathway diagram for this reaction.

energy

progress of reaction
Fig. 4.1

(i)Complete Fig. 4.1 by writing these formulae on the diagram:
● 2HBr
● H2 + Br2.[1]



(ii)Explain how Fig. 4.1 shows that the reaction is endothermic.



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



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



(iii)Complete this sentence about an endothermic reaction using a word from the list.
products

reactants

bromine

surroundings

An endothermic reaction transfers thermal energy from the ................................. .

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[1]


7


(c)Hydrobromic acid is formed when hydrogen bromide dissolves in water.
(i)Write the formula of the ion which is present in all acids.





........................................................................................................................................ [1]
(ii)Complete the word equation for the reaction of any acid with any carbonate.

acid

+

carbonate

→

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

+

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

+

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

[3]


(iii)A few drops of litmus indicator are added to a dilute acid.

State the colour of the solution.


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

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8

(d)Fig. 4.2 shows the apparatus used for the electrolysis of molten lead(II) bromide using graphite
electrodes.
– power +
supply

Fig. 4.2




(i)Label Fig. 4.2 to show:
● the cathode
● 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]


(iii)State one property of graphite that makes it useful as an electrode.



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



[Total: 18]

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9
5This question is about metals.


(a)Nickel is a transition element. Sodium is an element in Group I of the Periodic Table.

State two differences in the physical properties of nickel compared to sodium.
1 ..................................................................................................................................................
2 ..................................................................................................................................................
[2]


(b)Stainless steel is an alloy that is used to make cutlery.

Give one reason why stainless steel is used to make cutlery.



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

reaction with oxygen

gold

no reaction

lanthanum

forms a layer of oxide rapidly but does not burn

magnesium

burns rapidly to form an oxide

nickel

forms a layer of oxide slowly but does not burn

Put the four metals in order of their reactivity.

Put the least reactive metal first.
least reactive

most reactive

[2]


(d) Complete the diagram in Fig. 5.1 to show the electronic configuration of a magnesium atom.

Mg

Fig. 5.1
[1]

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[Total: 6]
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10
6

(a) A
 student investigates the reaction of magnesium with dilute hydrochloric acid at three different
temperatures.

The temperatures are:
● 20  °C
● 30  °C
● 40  °C.
All other conditions stay the same.


Table 6.1 shows the time taken for each reaction to finish.
Table 6.1
temperature
/ °C

time taken for the
reaction to finish / s
45
210
95



(i) Complete Table 6.1 by writing the temperatures in the first column.

(ii) D
 escribe the effect on the time taken for the magnesium to finish reacting with dilute
hydrochloric acid when the surface area of the magnesium is increased.

[1]

All other conditions stay the same.


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



(iii) D
 escribe the effect on the time taken for the magnesium to finish reacting with dilute
hydrochloric acid when the concentration of acid is decreased.

All other conditions stay the same.


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



(b)
Describe how crystals of magnesium chloride can be prepared after reacting excess
magnesium with dilute hydrochloric acid.

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



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



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

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11


(c)Magnesium chloride is soluble in water.

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


ammonium sulfate



calcium carbonate

iron(II) hydroxide

silver chloride
[1]


© UCLES 2023

[Total: 6]

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12
7

(a)Fig. 7.1 shows the displayed formula of compound E.
H
C

H
H

C

H

C
H

C
H

H
O

H

Fig. 7.1


(i)On Fig. 7.1 draw a circle around the functional group that makes compound E unsaturated.
[1]



(ii)Deduce the molecular formula of compound E.



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



(iii)Describe a chemical test to distinguish between a saturated and an unsaturated compound.

test .......................................................................................................................................

observations with saturated compound ...............................................................................



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



observations with unsaturated compound ...........................................................................


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



(b)Alcohols have an –OH functional group.
(i)Write the general formula for the alcohol homologous series.



© UCLES 2023

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

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13


(ii)Ethanol is an alcohol with two carbon atoms in each molecule.

Draw the displayed formula of ethanol.

[1]


(c)Ethanol reacts to form a compound with the formula C6H12O2.

Complete Table 7.1 to calculate the relative molecular mass of C6H12O2.
Table 7.1
atom

number of atoms

relative
atomic mass

carbon

6

12

hydrogen

1

oxygen

16





6 × 12 = 72

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

(d) Ethanol can be manufactured by the fermentation of aqueous glucose.

State two conditions for fermentation.
1 ..................................................................................................................................................
2 ..................................................................................................................................................
[2]

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14

(e)Ethanol can be oxidised to ethanoic acid.

Complete the word equation for the reaction of ethanoic acid with sodium.
ethanoic
acid

+

sodium

→

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

+

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

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

[2]


© UCLES 2023

[Total: 13]

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15
8This question is about non-metals.


(a)Non-metals are poor thermal conductors.

Describe two other physical properties which are typical of non-metals.
1 ..................................................................................................................................................
2 ..................................................................................................................................................
[2]


(b)Carbon dioxide contributes to increased global warming which leads to climate change.

State two strategies which help to reduce climate change caused by carbon dioxide.
1 ..................................................................................................................................................
2 ..................................................................................................................................................
[2]



(c)Water is a simple molecular compound.
(i)Complete Fig. 8.1 to show the dot-and-cross diagram for a molecule of water.

Show outer shell electrons only.

O
H

H

Fig. 8.1
[2]


(ii)State two properties of simple molecular compounds.

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


(iii)Water is a good solvent.

State the meaning of the term solvent.


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

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16


(iv)Pure water has a neutral pH value.

Choose from the list, the pH value that is neutral.
Draw a circle around your chosen answer.
pH 1




pH 3

pH 7

pH 14[1]

(v)A crystal of blue copper(II) sulfate is placed at the bottom of a beaker of water as shown
in Fig. 8.2.

water

crystal of
copper(II) sulfate
at first

after one day
Fig. 8.2

After one day, the blue colour has spread throughout the water in the beaker.
Explain these results in terms of the kinetic particle theory.

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



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



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



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



[Total: 13]

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18
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© UCLES 2023

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19
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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

0620/33/M/J/23


© UCLES 2023

12

V

Cr

Mn

Co

27

Ni

28

Cu

29

Zn

30

Fe

57–71

56

55

0620/33/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

0620/33

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 10 printed pages.
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0620/33

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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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.

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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6

Cambridge IGCSE – Mark Scheme
PUBLISHED

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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Cambridge IGCSE – Mark Scheme
PUBLISHED

Question

Answer

May/June 2023
Marks

1(a)

C

1

1(b)

N

1

1(c)

I

1

1(d)

Li

1

1(e)

Fe

1

1(f)

Al

1

Question

Answer

Marks

2(a)(i)

values between –100 °C and +10 °C (inclusive of these values)

1

2(a)(ii)

values lower than 0.003

1

2(a)(iii)

solid (1)

2

100 °C is lower than the melting point / the melting point is above 100 °C (1)
2(b)(i)

bromine (1)

2

sodium chloride (1)
2(b)(ii)

flame test / put sodium (compound) in (non-luminous) flame (1)
(flame colour) yellow (1)

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