IGCSE 0620

PAPER4 (MS)
Cambridge IGCSE™

CHEMISTRY 0620/41
Paper 4 Theory (Extended) 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 12 printed pages.

© UCLES 2023 [Turn over

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Generic Marking Principles

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.

© UCLES 2023 Page 2 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
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.

© UCLES 2023 Page 3 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
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.

© UCLES 2023 Page 4 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
6 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.

© UCLES 2023 Page 5 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

1(a) B 1

1(b) A 1

1(c) H 1

1(d) J 1

1(e) G 1

1(f) D 1

Question Answer Marks

2(a)(i) N 1

2(a)(ii) B 1

2(a)(iii) F 1

2(a)(iv) C 1

2(a)(v) Li 1

2(a)(vi) Ne 1

2(b)(i) M1 different atoms of the same element with the same number of protons(1) 2

M2 different numbers of neutrons(1)

© UCLES 2023 Page 6 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

2(b)(ii) M1 10  20 + 2
11 80
( = 1080)(1)

M2 (1080 ÷ 100 =) 10.8(1)

Question Answer Marks

3(a)(i) M1 Na with 2,8 all crosses(1) 3

M2 O with 2,8 outer shell with 6 dots and 2 crosses(1)

M3 + AND 2(1)

3(a)(ii) Na2O 1

3(b) M1 both bonds with 2 dots and 2 crosses(1) 2

M2 2 lone pairs
(all dots or all crosses) on both oxygen atoms completing all 3 octets(1)

3(c)(i) M1 positive ions and negative ions (1) 2

M2 strong attraction / strong bonds (1)

3(c)(ii) intermolecular forces 1

© UCLES 2023 Page 7 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

4(a) M1 increases the rate of reaction / 2

speeds up a reaction(1)

M2 unchanged at the end of the reaction(1)

4(b)(i) oxygen escapes from the flask or apparatus 1

4(b)(ii) concentration of hydrogen peroxide is highest at the start / particles of hydrogen peroxide are closest together at the start 1

OR

collision frequency is highest at the start

4(b)(iii) the hydrogen peroxide is used up / 1

ALL the hydrogen peroxide has reacted or decomposed

4(c) M1 kinetic energy of particles increases(1) 3

M2 frequency of collisions between particles increases(1)

M3 more or higher percentage or higher proportion or

higher fraction of particles have energy greater than / equal to activation energy

OR
more of the collisions or higher percentage or higher fraction of collisions have energy greater than or equal to activation
energy(1)

4(d) M1 (50.0  0.200 ÷ 1000 =) 0.01(1) 3

M2 0.005(1)

M3 0.16(0)(1)

4(e) no effect 1

© UCLES 2023 Page 8 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

4(f) 2HgO → 2Hg + O2 2

M1 all formulae correct(1)

M2 equation correct(1)

5(a)(i) M1 breakdown by (the passage of) electricity(1) 2

M2 of an ionic compound in molten or aqueous (state) (1)

Question Answer Marks

5(a)(ii) graphite is inert AND graphite conducts electricity 1

5(a)(iii) 2H+ + 2e– → H2 2

M1 H+ + e as only species on LHS(1)

M2 equation correct(1)

5(a)(iv) electrons 1

5(a)(v) ions 1

5(a)(vi) M1 oxygen(1) 2
M2 hydrogen(1)

5(b)(i) aluminium oxide 1

5(b)(ii) any two from: 2

 solvent
 lowers the operating temperature
 increases conductivity

5(b)(iii) carbon reacts with oxygen and forms carbon dioxide 1

© UCLES 2023 Page 9 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

5(c)(i) 2H2 + O2 → 2H2O 2

M1 all formulae(1) M2 equation correct(1)

5(c)(ii) no carbon dioxide evolved 1

OR
more efficient

Question Answer Marks

6(a)(i) 4FeS2 + 11O2 → 2Fe2O3 + 8SO2 1

6(a)(ii) iron(III) oxide 1

6(b)(i) yield of SO3 is less 1

6(b)(ii) yield of SO3 is less 1

OR

rate is less

6(c) 2NH3 + H2SO4 →(NH4)2SO4 2

M1 (NH4)2SO4 on the right (1)

M2 equation correct(1)

6(d)(i) lead(II) nitrate 1

© UCLES 2023 Page 10 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

6(d)(ii) Pb2+ (aq) +SO42-(aq) → PbSO4(s) 3

M1 PbSO4 on the right(1)

M2 only Pb2+ and SO42– on the left(1)

M3(aq) + (aq) → (s)(1)

6(d)(iii) M1 filter(1) 3

M2 wash (the residue or lead sulfate) with distilled or deionised water(1)

M3 description of drying(1)

Question Answer Marks

7(a)(i) needs or uses ultra violet light 1

7(a)(ii) M1 displayed formula of 1-chlorobutane(1) 2

M2 displayed formula of 2-chlorobutane(1)

7(b)(i) C4H6O3 1

7(b)(ii) M1 alkene(1) 3

M2 alcohol(1)

M3 carboxylic acid(1)

7(b)(iii) M1 turns colourless(1) 2

M2 bubbles / fizzing / effervescence(1)

© UCLES 2023 Page 11 of 12

0620/41 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

7(b)(iv) M1 only two carbon atoms joined by a single bond and two additional bonds on each(1) 2

M2

(1)

7(b)(v) polyester 1

© UCLES 2023 Page 12 of 12

Cambridge IGCSE™

CHEMISTRY 0620/42
Paper 4 Theory (Extended) 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.

© UCLES 2023 [Turn over

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Check the page above Q1(a) and assuming no relevant work is there, place ‘SEEN’ on the page
For equations, allow multiples (including fractions); ignore state symbols except Q2(f)(ii)

Question Answer Marks

1(a) D 1

1(b) C 1

1(c) H 1

1(d) B 1

1(e) C 1

1(f) G 1

Question Answer Marks

2(a) halogen(s) 1

2(b) same number of outer shell electrons 1

2(c) 3
gas

M1 pale yellow-green gas

M2 red-brown

M3 both gases

2(d)(i) nucleon number / mass number 1

© UCLES 2023 Page 5 of 10

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

2(d)(ii) 79Br 81Br– 3

protons 35 35

neutrons 44 46

electrons 35 36

Each row ✔

2(d)(iii) M1 79  55(%) + 81  45(%) 2

M2 7990 / 100 = 79.9

2(e)(i) Cl2 + 2KBr  2KCl + Br2 2

M1 KCl as product
M2 correct equation

2(e)(ii) chlorine less reactive than fluorine 1

2(f)(i) white precipitate 1

2(f)(ii) Ag+(aq) + Cl –(aq)  AgCl(s) 3

M1 AgCl as only product
M2 Ag+ + Cl – as only reactants (in 1 : 1 ratio)
M3 state symbols

© UCLES 2023 Page 6 of 10

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

3(a) contact (process) 1

3(b(i) M1 burning sulfur (in air) 2

M2 Roasting sulfide ores (in air)

3(b)(ii) M1 the rate of forward reaction equals (the rate of the) reverse reaction 2
M2 concentrations of reactants and products are constant

3(b)(iii) 450 (oC) 3

200 (kPa)

vanadium(V) oxide

3(b)(iv) 4
increases

increases increase

no change

3(b)(v) M1 kinetic energy of particles decreases 3

M2 frequency of collisions between particles decreases

M3 lower percentage / proportion / fraction of collisions / particles have energy greater than / qual to activation energy
OR
fewer of the collisions / particles have energy greater than / equal to activation energy

3(c) M1 4  2 or 8 2
M2 S + (4  –2) = –2 ∴ S = + 6

© UCLES 2023 Page 7 of 10

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

4(a) proton acceptor 1

4(b) alkali 1

4(c) blue 1

4(d) M1 sodium chloride 3

M2 water
M3 ammonia

4(e)(i) amphoteric (oxides) 1

4(e)(ii) aluminium oxide 1

or
zinc oxide

4(f)(i) M1 all single bonding dot and cross pairs correct 3

M2 double C = O bond dot and cross pairs are correct
M3 complete diagram is correct

4(f)(ii) 3≤ pH < 7 1

4(f)(iii)i CH3COOH ⇌ CH3COO– + H+ 3

M1 H+
M2 CH3COO–
M3 use of ⇌

4(f)(iv) H+ + OH–  H2O 1

© UCLES 2023 Page 8 of 10

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

4(g) M1 mol KOH = 0.0800  25 / 1000 5

= 0.002(00) / 2(00)  10–3

M2 mol H2SO4 = M1 / 2 = 0.002 / 2

= 0.001(00) / 1(00  10–3

M3 = M2  1000 / 20 = 0.001  1000 / 20

= 0.05(00) / 5.(00)  10–2

M4 = 98

M5 = 98  M3 = 98  0.05(00) = 4.9(0) (g / dm3)

Question Answer Marks

5(a)(i) substitution 1

5(a)(ii) provide activation energy 1

5(a)(iii) photochemical 1

5(a)(iv) C3H8 + Cl2  C3H7Cl + HCl 2

M1 HCl M2 equation correct

5(b)(i) it has a carbon-carbon bond which is not a single bond 1

5(b)(ii) CH3CHClCH2Cl 1

© UCLES 2023 Page 9 of 10

0620/42 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

5(c) M1 displayed formula of propan-1-ol 4

M2 displayed formula of propan-2-ol

M3 propan-1-ol
(as either name)

M4 propan-2-ol (under displayed formula of propan-2-ol)

Question Answer Marks

6(a) ethyl butanoate 1

6(b) water 1

6(c) C3H6O 1

6(d)(i) 1 repeat unit circled 1

6(d)(ii) M1 displayed diol on correct box (unshaded) 2

M2 displayed dioic acid on correct box (shaded)

6(d)(iii) condensation 1

© UCLES 2023 Page 10 of 10

Cambridge IGCSE™

CHEMISTRY 0620/43
Paper 4 Theory (Extended) 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.

© UCLES 2023 [Turn over

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

1(a) J 1

1(b) D 1

1(c) B 1

1(d) G 1

1(e) F 1

1(f) C 1

Question Answer Marks

2(a)(i) Al 1

2(a)(ii) Ar 1

2(a)(iii) Cl 1

2(a)(iv) Al 1

2(a)(v) S 1

2(a)(vi) Cl 1

2(b)(i) 12C 1

2(b)(ii) M1 24  85(%) + 26  15(%) 2

M2 2430 / 100 = 24.3

2(c)(i) 27 1

2(c)(ii) Aluminium / Al 1

© UCLES 2023 Page 6 of 11

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

3(a)(i) M1 eight crosses in second shell of Mg 3

M2 7 dots and 1 cross in second shell of F

M3 ‘2+’ charge on Mg ion on correct answer line

and ‘–‘ charge on F ion on correct answer line

3(a)(ii) MgF2 1

3(a)(iii) melting 1

3(b) M1 4 dot and cross single bonds 2

M2 3 pairs of non-bonding e on each Cl and no non-bonding e on Si

3(c)(i) molecule(s) 1

3(c)(ii) M1 covalent bonds 2

M2 strong bonds

and

giant (covalent) structure

Question Answer Marks

4(a)(i) concentration (of sulfuric acid particles) decreases 1

OR

frequency of collisions between particles decreases

4(a)(ii) all the (sulfuric) acid has reacted 1

© UCLES 2023 Page 7 of 11

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

4(b) M1 greater surface area (of zinc) 2

M2 frequency of collisions between (zinc and acid) particles increases

4(c) M1 mol H2SO4 = 2.00 x 25.0/1000 = 0.05(00) 3

M2 mol H2 = M1 = 0.05(00)

M3 vol H2 = M2  24 = 1.2(0)

4(d)(i) Zn + 2HCl → ZnCl2 + H2 2

M1 ZnCl2
M2 equation correct

4(d)(ii) lighted splint and (squeaky) pop 1

Question Answer Marks

5(a)(i) M1 ionic compound 2

M2 molten and / or aqueous

5(a)(ii) oxidation number (of copper) 1

5(a)(iii) fades / (becomes) colourless 1

5(a)(iv) Cu2+ + 2e → Cu 2

M1 Cu2+ and (any number of) e on left hand side

M2 equation correct

5(a)(v) OH– 1

5(b) anode dissolves 1

© UCLES 2023 Page 8 of 11

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

5(c)(i) M1 silver 3

M2 spoon

M3 (aqueous or solution) of silver nitrate

5(c)(ii) M1 prevent corrosion 2

M2 improve appearance

5(d)(i) M1 carbon dioxide: (increased) global warming 2

M2 carbon monoxide: toxic

5(d)(ii) needs high pressure to store hydrogen 1

Question Answer Marks

6(a)(i) air 1

6(a)(ii) methane 1

6(a)(iii) M1 450 (°C) 2

M2 200 (atm)

6(a)(iv) iron 1

6(a)(v) M1 (a substance which) increases the rate of a reaction 2

M2 remains unchanged at the end of the reaction

© UCLES 2023 Page 9 of 11

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

6(b)(i) temperature change: 2

M1 low(er) rate (of reaction)

pressure change:
M2 (position of) equilibrium shifts to the left hand side/ towards reactants

6(b)(ii) 4NO + 3O2 + 2H2O →.4HNO3 1

6(c)(i) CuCO3 + 2HNO3 → Cu(NO3)2 + CO2 + H2O 2

M1 Cu(NO3)2
M2 correct equation

6(c)(ii) M1 undissolved solid 2

M2 effervescence stops on addition of more copper(II) carbonate

6(d)(iii) copper(II) oxide or 1

copper(II) hydroxide

Question Answer Marks

7(a)(i) ultraviolet (light) 1

7(a)(ii) M1 displayed formula of 2

1–chloropropane

M2 displayed formula of 2–chloropropane

7(b)(i) any 2 from: 2

(same) general formula

(same / similar) chemical properties or reactions

(contain the same) functional group

© UCLES 2023 Page 10 of 11

0620/43 Cambridge IGCSE – Mark Scheme May/June 2023
PUBLISHED
Question Answer Marks

7(b)(ii) M1 single bond between the two C atoms (and nothing on continuation bonds) 2

M2 1 CH3 group and 1 H on first carbon and 1 CH3 group and 1 H on second carbon and whole structure correct

7(c)(i) M1 structural formula of 2

propan-1,3-dioic acid

M2 structural formula of
ethan-1,2-diol

7(c)(ii) polyester 1

7(c)(iii) M1 carboxylic acids 2

M2 alcohols

© UCLES 2023 Page 11 of 11

Cambridge IGCSE™

CHEMISTRY 0620/41
Paper 4 Theory (Extended) May/June 2024
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 2024 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.

© Cambridge University Press & Assessment 2024 [Turn over

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
If the candidate uses different terminology to the terminology on the Mark Scheme full credit must be given if the meaning is the same.

Any response that is worth more than 1 mark must be annotated by tick(s). The number of ticks should be the same as the number of
marks awarded. This applies even if other annotations such as BOD or ECF are used. Ticks should be placed as near as possible to the
place where the mark is awarded. Please see Practice scripts for examples.

Question Answer Marks

1(a) Contact process 1

1(b) distillation 1

1(c) electrolysis 1

1(d) fractional distillation 1

1(e) fermentation 1

1(f) cracking 1

1(g) chromatography 1

Question Answer Marks

2 M1 : Cl : 17 AND 20 (1) 5

M2 Cu+: 29 AND 28 (1)

M3 33(above) and 16(below) on left hand side of symbol (1)

M4 S (1)

M5 2– (1)

© Cambridge University Press & Assessment 2024 Page 5 of 11

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

3(a) 2Na + F2 → 2NaF(2) 2

M1 NaF(1)
Has to be the only product

M2 equation completely correct(1)

3(b)(i) electrons move 1

OR
electrons are mobile
OR
electrons flow

3(b)(ii) M1 one shared dot and cross(1) 2

M2 6 non–bonding electrons (either) dots or crosses on each fluorine atom to complete both octets (1)

3(b)(iii) M1 liquid(1) 2

M2 BOTH melting point is below –200 °C AND boiling point is above –200 °C(1)

OR

BOTH –200 oC is higher than –220 °C/ melting point AND lower than –188 °C/ boiling point(1)

OR
–200 °C is between melting point or –220 °C and boiling point or
–188 °C(1)

3(b)(iv) M1 ionic bonds in NaF(1) 3

M2 attraction between molecules or intermolecular forces in F2(1)

M3 weaker attraction (between particles) in F2 ORA (1)

© Cambridge University Press & Assessment 2024 Page 6 of 11

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

3(c)(i) M1 breakdown by (the passage of) electricity(1) 2

M2 of an ionic compound in molten or aqueous (state) (1)

3(c)(ii) 2H+ + 2e(–) → H2 2

M1 H+ + e(–) on left hand side(1)

M2 equation fully correct(1)

Question Answer Marks

4(a) M1 The rate of forward reaction equals the rate of the reverse reaction(1) 2

M2 concentrations of reactants and products are no longer changing(1)

4(b)(i) same number of gas moles on both sides of the equilibrium 1

OR

same number of gas molecules on both sides of the equilibrium

4(b)(ii) iodine particles or molecules (forced) closer together 1

OR

same number of iodine particles or molecules in a smaller volume

4(c) endothermic 1

4(d) M1 –1 (1) 2

M2 zero (1)

4(e)(i) copper 1

© Cambridge University Press & Assessment 2024 Page 7 of 11

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

4(e)(ii) no effect 1

4(e)(iii) (activation energy is) lower 1

Question Answer Marks

5(a)(i) M1 lead(II) nitrate(1) 2

M2 sodium bromide /
potassium bromide /
ammonium bromide(1)

5(a)(ii) M1 filter precipitate or lead(II) bromide or solid or residue(1) 2

M2 wash the residue with distilled water AND dry e.g. between filter papers(1)

5(a)(iii) Pb2+(aq) + 2Br–(aq) → PbBr2(s) 3

M1 PbBr2 as the only product (1)

M2 Pb2+ + 2Br– as the only reactants in a balanced equation(1)

M3 state symbols
(aq) + (aq) → (s)(1)

5(b) M1 acidified aqueous potassium manganate(VII) (1) 2

M2 purple to colourless (1)

5(c) M1 2CoO + 4NO2 (1) 2

M2 8H2O (1)

© Cambridge University Press & Assessment 2024 Page 8 of 11

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

5(d)(i) M1 heat again and weigh again 2

OR

repeat steps 2 and 3(1)

M2 until mass is constant (1)

5(d)(ii) M1 0.005 / 5 10–3 (1) 4

M2 0.63 (1)

M3 (0.63 / 18 =) 0.035 (1)

M4 (0.035 ÷ 0.005 =) 7 (1)

Question Answer Marks

6(a)(i) limestone 1
OR
calcium carbonate

6(a)(ii) (molten) iron 1

6(a)(iii) silicon(IV) oxide 1

OR
silicon dioxide

6(a)(iv) coke or carbon and oxygen 1

6(a)(v) Any two from: 2

 nitrogen
 carbon dioxide
 argon
© Cambridge University Press & Assessment 2024 Page 9 of 11
0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

6(b)(i) the temperature in the furnace is above or higher than the boiling point of zinc ORA 1

OR

the boiling point of zinc is below or less than the temperature of the furnace ORA

6(b)(ii) condensation / condensing 1

6(c)(i) galvanising 1

6(c)(ii) M1 zinc is more reactive than iron (1) 2

M2 zinc is oxidised /
zinc loses electrons /
zinc forms positive ions /
zinc forms zinc ions (1)

6(d)(i) amphoteric 1

6(d)(ii) Na2ZnO2 1

6(d)(iii) zinc sulfate 1

Question Answer Marks

7(a)(i) M1 C 82.76 / 12: H 17.24/1 (1) 3

OR evaluation i.e.
6.90:17.24

M2 fractions showing division of both by smaller ie 6.9 / 6.9 and 17.24 / 6.9

OR evaluation ie 1:2.5 OR 4:10

M3 C2H5 (1)

© Cambridge University Press & Assessment 2024 Page 10 of 11

0620/41 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

7(a)(ii) C5H10 1

7(b) M1 3

any C=C with both carbons having a valency of 4(1)

M2 correct displayed formula of (cis or trans) but–2–ene(1)

M3 but–2–ene

7(c) C8H16 1

7(d)(i) structural isomers 1

7(d)(ii) M1 ethanoic acid(1) 2

M2 methanol(1)

7(d)(iii) M1 Displayed formula of propanoic acid showing ALL atoms and bonds 2

(1)

M2 propanoic acid(1)

© Cambridge University Press & Assessment 2024 Page 11 of 11

Cambridge IGCSE™

CHEMISTRY 0620/42
Paper 4 Theory (Extended) May/June 2024
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 2024 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 9 printed pages.

© Cambridge University Press & Assessment 2024 [Turn over

0620/42 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

1(a)(i) methane 1

1(a)(ii) nitrogen dioxide 1

1(a)(iii) propene 1

1(a)(iv) helium 1

1(a)(v) carbon monoxide 1

1(b) 2NO2 + 4CO → N2 + 4CO2 2

M1 N2 + CO2 as only products
M2 correct equation

Question Answer Marks

2(a)(i) electron loss (from outer shell) 1

2(a)(ii) potassium 1

2(a)(iii) magnesium or potassium 1

2(a)(iv) iron 1

2(b) 3
M1 Colourless

M2 Blue M3 Colour given in

M2

2(c)(i) hydrogen 1

2(c)(ii) strontium hydroxide 1

© Cambridge University Press & Assessment 2024 Page 5 of 9

0620/42 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

2(c)(iii) M1 magnesium or Mg 2

M2 magnesium oxide

2(d) Fe3O4 + 8HCl → 2FeCl3 + FeCl2 + 4H2O 3

M1 FeCl2 or FeCl3 as product of equation
M2 FeCl2 and FeCl3 and H2O as only products of equation
M3 Correct equation

Question Answer Marks

3(a) Haber 1

3(b) enthalpy change (of reaction) 1

3(c) 450 and C 3

200 and atm or 20 000 and kPa

iron

3(d) M1 increase temperature 2

M2 increase pressure

3(e) M1 bond energy in breaking bonds 3

= [945 + (3  435)] = (+) 2250 (kJ / mol)

M2 = 2250 + 90 = 2340

M3 = 2340 / 6 = 390

3(f)(i) H2O 1

3(f)(ii) Ammonium chloride 1

© Cambridge University Press & Assessment 2024 Page 6 of 9

0620/42 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

3(f)(iii) M1 mol CaO = 1.12 / 56 = 0.02(00) 3

M2 mol NH3 = M1  2 = 0.02(00)  2 = 0.04(00)

M3 vol NH3 = M2  24000 = 0.04  24000 = 960

Question Answer Marks

4(a) C2H4O 1

4(b) methyl propanoate 1

4(c) M1 displayed formula of propanoic acid 2

M2 propanoic acid

4(d) M1 structure of CH3OH 2

M2 methanol

4(e) M1 decreases 4
M2 decreases
M3 decreases
M4 no effect

4(f)(i) M1 7 2
M2 3 ⩾ pH  7

4(f)(ii) H+(aq) 1

4(f)(iii) universal indicator 1

© Cambridge University Press & Assessment 2024 Page 7 of 9

0620/42 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

5(a)(i) 32S 34S 2

protons 16 16

neutrons 16 18

5(a)(ii) same electronic configuration / structure 1

5(a)(iii) 34 and g 1

5(a)(iv) 1 mole 1

5(a)(v) M1 (32  95) + (34  5) = 3210 2

M2 3210 / 100 = 32.1

5(b)(i) M1 eight crosses in second shell of Mg 3

M2 6 dots and 2 cross in third shell of S
M3 ‘2+’ charge on Mg on correct answer line
and ‘2–’ charge on S on correct answer line

5(b)(ii) ionic bonds are strong 1

5(b)(iii) mobile ions 1

5(c)(i) H2SO3 1

5(c)(ii) SO32– 1

5(d)(i) the oxidation number of manganese / Mn is +7 1

5(d)(ii) M1 purple 2
to
M2 colourless

© Cambridge University Press & Assessment 2024 Page 8 of 9

0620/42 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

6(a)(i) photosynthesis 1

6(a)(ii) 6CO2 + 6H2O → C6H12O6 + 6O2 1

6(a)(iii) M1 energy from light 2

M2 presence of chlorophyll

6(b)(i) fermentation 1

6(b)(ii) carbon dioxide 1

6(c)(i) M1 300 C 3
M2 60 atm or 6000 kPa
M3 acid

6(c)(ii) only one product is formed 1

6(c)(iii) M1 C–C bond as dot and cross and C–O as ‘cross and dot’ 3

M2 all C–H bonds and O–H bond as dot and cross

M3 4 non-bonding dot electrons on O atom and no other non-bonding electrons on C or H

© Cambridge University Press & Assessment 2024 Page 9 of 9

Cambridge IGCSE™

CHEMISTRY 0620/43
Paper 4 Theory (Extended) May/June 2024
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 2024 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 12 printed pages.

© Cambridge University Press & Assessment 2024 [Turn over

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

1(a) Haber (process) 1

1(b) electrolysis 1

1(c) filtration 1

1(d) catalytic addition 1

1(e) chromatography 1

1(f) fractional distillation 1

1(g) titration 1

Question Answer Marks

2 M1 Cu: 29 and 34 5
M2 Cl– : 17 and 18
M3 6430 to left of symbol
M4 Zn
M5 2+

© Cambridge University Press & Assessment 2024 Page 5 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

3(a)(i) mobile electrons 1

3(a)(ii) M1 double bond of two dots and two crosses 2

M2 4 non-bonding electrons on each oxygen atom

3(a)(iii) M1 liquid 2

M2 melting point is below –195 °C and boiling point is above –195 °C

or

–195 °C is higher than –199 °C / melting point and lower than –191 °C / boiling point

or

–195 °C is in between melting point / –199 °C and boiling point / –191 °C

3(a)(iv) M1 graphite has a giant covalent structure 3

M2 attraction between molecules in carbon monoxide

M3 weaker attraction (between particles) in carbon monoxide ORA

3(b) 2K + Cl2 → 2KCl 2

M1 KCl as only product

M2 correct equation

3(c)(i) M1 breakdown by (the passage of) electricity 2

M2 of an ionic compound in molten or aqueous (state)

© Cambridge University Press & Assessment 2024 Page 6 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

3(c)(ii) 4OH– → 2H2O + O2 + 4e– 2

M1 any negatively charged OH species losing electrons

M2 correct ionic half-equation

Question Answer Marks

4(a) M1 (rates are) equal 2

M2 (concentrations are) no longer changing

4(b) more molecules of nitrogen dioxide per unit volume 1

OR
same number of nitrogen dioxide molecules in a smaller volume

4(c) (the forward reaction is) endothermic 1

4(d)(i) 4
M1 M3 no
increases change

M2 M4
increases increases

4(d)(ii) M1 (the oxidation number of sulfur in S) = zero 2

M2 (the oxidation number of sulfur in SO3) = +6

© Cambridge University Press & Assessment 2024 Page 7 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

5(a)(i) M1 named soluble barium salt e.g. barium chloride / barium nitrate 2

M2 named soluble sulfate salt

e.g. sodium sulfate / potassium sulfate / ammonium sulfate / sulfuric acid

5(a)(ii) M1 filter 2

M2 wash (residue) with water

and

dry (residue) between filter papers / in a warm place

5(a)(iii) Ba2+ (aq) + SO42– (aq) → BaSO4(s) 3

M1 BaSO4 as only product

M2 Ba2+ + SO42– as only reactants

M3 state symbols

5(b) M1 sulfuric (acid) 2

M2 copper(II) carbonate / copper(II) oxide / copper(II) hydroxide

5(c)(i) glowing splint and relights 1

5(c)(ii) M1 2CuO + 4NO2 2

M2 6H2O

5(d)(i) (To ensure that) all the water is given off 1

© Cambridge University Press & Assessment 2024 Page 8 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

5(d)(ii) M1 mol ZnSO4 4

(0.322 / 161 =) 0.002(00)

M2 mass H2O given off

(0.574 – 0.322 =) 0.252

M3 mol H2O given off

(0.252 ÷ 18 =) 0.014(0)

M4 value of x
(0.014 ÷ 0.002 =) 7

Question Answer Marks

6(a)(i) hematite 1

6(a)(ii) air 1

6(a)(iii) carbon monoxide 1

6(a)(iv) M1 limestone thermally decomposes (into calcium oxide and carbon dioxide) 3

M2 calcium oxide reacts with silicon(IV) oxide

M3 producing slag

6(b)(i) have low densities 1

or
have low melting point

6(b)(ii) act as catalysts 1

or
form coloured compounds

© Cambridge University Press & Assessment 2024 Page 9 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

6(b)(iii) form basic oxides 1

or
form positive ions

6(b)(iv) form acidic oxides 1

or
form negative ions

6(c)(i) M1 magnesium loses electrons more readily than / in preference to / instead of iron 2

M2 magnesium is more reactive than iron ORA

6(c)(ii) any metal below iron in the reactivity series e.g. copper / silver / gold 1

© Cambridge University Press & Assessment 2024 Page 10 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

7(a)(i) M1 C 83.33 / 12: H 16.67 / 1 3

or

6.94:16.67

M2 C 6.94 / 6.94: H 16.67 / 6.94

or 1:2.4

or 5:12

M3 C5H12

7(a)(ii) M1 Mr of C2H5 = 29 2

M2 58 / 29 = 2 and C4H10

7(b)(i) C=C 1

7(b)(ii) M1 3

C C

any C=C with both carbons having a valency of 4

M2 displayed formula of
but-1-ene

M3 but-1-ene

© Cambridge University Press & Assessment 2024 Page 11 of 12

0620/43 Cambridge IGCSE – Mark Scheme May/June 2024
PUBLISHED
Question Answer Marks

7(c) M1 2C2H4 2

M2 C8H18

7(d)(i) CnH2n + 1OH 1

7(d)(ii) M1 displayed formula of propan-1-ol or propan-2-ol 2

M2 propan-1-ol
or
propan-2-ol

© Cambridge University Press & Assessment 2024 Page 12 of 12

Cambridge IGCSE™

CHEMISTRY 0620/41
Paper 4 Theory (Extended) October/November 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 October/November 2023 series for most
Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level
components.

This document consists of 10 printed pages.

© UCLES 2023 [Turn over

0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

1(a) sulfur dioxide 1

1(b) ammonia 1

1(c) xenon 1

1(d) oxygen 1

1(e) ethene 1

1(f) ammonia 1

Question Answer Marks

2(a) M1 5p and 5e (1) 2

M2 6n (1)

2(b)(i) 20% 1

2(b)(ii) M1 0.540 / 10.8 = 0.05(0) mol (1) 2

M2 0.05  6.02  1023 = 3.01  1022 (1)

2(c)(i) bauxite 1

2(c)(ii) M1 cryolite (1) 2

M2 lowers operating temperature OR improves conductivity (1)

2(c)(iii) Al3+ + 3e– → Al 2

M1 Al3+ + 3e– on the left-hand side (1)

M2 equation correct (1)

© UCLES 2023 Page 5 of 10

0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

2(c)(iv) M1 (anodes of) carbon react with oxygen (formed at the anode) (1) 2

M2 (form) carbon dioxide (1)

2(d) M1 (good) conductor (of electricity) (1) 2

M2 low density (1)

2(e) M1 aluminium oxide layer (1) 2

M2 (oxide layer) is unreactive (1)

2(f)(i) 2Al + 3F2 → 2AlF3 2

M1 Al and F2 as reactants (1)

M2 equation correct (1)

2(f)(ii) M1 eight crosses in second shell of Al (1) 3

M2 7 dots and 1 cross in second shell of F (1)

M3 3+ charge on Al ion on correct answer line and – charge on F ion on correct answer line (1)

Question Answer Marks

3(a)(i) M1 Ag column all ✗ (1) 3

M2 ✗ in Pb AND 2 ✓ in Zn (1)

M3 Zn, Mn, Pb Ag (1)

3(a)(ii) (all) nitrates are soluble OR lead sulfate is insoluble 1

© UCLES 2023 Page 6 of 10

0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

3(a)(iii) Zn + 2AgNO3 → Zn(NO3)2 + 2Ag 2

M1 Zn(NO3)2 on the right hand side (1)

M2 correct equation (1)

3(b)(i) M1 colourless (1) 2

M2 orange (1)

3(b)(ii) Cl2(g) + 2Br–(aq) → Br2(aq) + 2Cl–(aq) 3

M1 Br2 + Cl– as products (1)

M2 correct equation (1)

M3 state symbols (1)

3(b)(iii) tenessine / Ts 1

Question Answer Marks

4(a) test: relights 1

AND
observations: a glowing splint

4(b)(i) lower gradient (at t2) 1

4(b)(ii) M1 concentration (of H2O2 particles) decreases (1) 2

M2 frequency of collisions between particles decreases (1)

© UCLES 2023 Page 7 of 10

0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

4(b)(iii) M1 steeper curve which does not cross original curve and levels off before the original curve (1) 2

M2 finishes at same volume (1)

4(c) M1 mol O2 = 72 / 24000 = 0.003(00) (1) 5

M2 mol H2O2 = M1  2 = 0.002  2 = 0.006(00) (1)

M3 conc H2O2 = M2  1000 / 20 = 0.006  1000 / 20 = 0.3(00) (1)

M4 Mr H2O2 = 34 (1)

M5 = M4  M3 = 34  0.3 = 10.2 (g / dm3) (1)

4(d) any transition metal oxide 1

Question Answer Marks

5(a) M1 the rate of forward reaction equals (the rate of the) reverse reaction (1) 2

M2 the concentrations of reactants and products are no longer changing (1)

5(b)(i) M1 concentration decreases (1) 2

M2 position of equilibrium shifts to left AND fewer moles of gas on left hand side (1)

5(b)(ii) M1 concentration increases (1) 2

M2 position of equilibrium shifts to the right AND forward reaction is endothermic (1)

5(b)(iii) M1 no change (1) 2

M2 catalysts do not affect position of equilibrium (1)

5(c)(i) carbon dioxide 1

© UCLES 2023 Page 8 of 10
0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

5(c)(ii) M1 greenhouse gases absorb thermal energy (from the Earth) (1) 3

M2 and M3 one mark each for any two of:

• energy (from the sun) absorbed by Earth’s surface
• Earth emits or reflects thermal energy
• (greenhouse gases) reduces or stops thermal energy loss (into space)
• increasing in amount of greenhouse gas results in a higher atmospheric temperature

Question Answer Marks

6(a) M1 yeast (1) 2

M2 absence of air (1)

6(b)(i) M1 300 (1) 2

M2 6000 (1)

6(b)(ii) ethene 1

6(b)(iii) only one product 1

6(c)(i) proton donor 1

6(c)(ii) partial dissociation 1

6(c)(iii) M1 4  –2 or –8 (1) 2

M2 P + (4  –2) = –3 ∴ P = +5 (1)

6(d) M1 uses renewable resources (1) 2

M2 high rate of reaction (1)

6(e)(i) potassium manganate(VII) 1

© UCLES 2023 Page 9 of 10
0620/41 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

6(e)(ii) reducing agent 1

6(f)(i) calcium ethanoate 1

6(f)(ii) (CH3COO)2Ca 1

6(f)(iii) hydrogen 1

© UCLES 2023 Page 10 of 10

Cambridge IGCSE™

CHEMISTRY 0620/42
Paper 4 Theory (Extended) October/November 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 October/November 2023 series for most
Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level
components.

This document consists of 10 printed pages.

© UCLES 2023 [Turn over

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

1(a) B 1

1(b) F 1

1(c) D 1

1(d) A AND E 1

1(e) G 1

1(f) C 1

1(g) B 1

1(h) F 1

Question Answer Marks

2(a)(i) 59 65 3
Co Cu2+

protons 27 29

neutrons 32 36

electrons 27 27

one mark for each correct row

2(a)(ii) M1 (63  70) + (65  30) = 6360 (1) 2

M2 6360 / 100 = 63.6 (1)

© UCLES 2023 Page 5 of 10

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

2(b) M1 (high) density (1) 2

M2 (high) melting point (1)

2(c)(i) M1 water molecules (1) 2

M2 (the water present) in hydrated crystals (1)

2(c)(ii) M1 pink (1) 2

M2 CoCl2∙6H2O (1)

2(c)(iii) M1 white (1) 2

M2 blue (1)

2(c)(iv) heating (the hydrated copper(II) sulfate) 1

Question Answer Marks

3(a) (hot) air 1

3(b)(i) hematite 1

3(b)(ii) Fe2O3 + 3CO → 3CO2 + 2Fe 1

3(b)(iii) M1 from +3 (1) 2

M2 to 0 (1)

3(b)(iv) decrease (in oxidation number) 1

© UCLES 2023 Page 6 of 10

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

3(c) M1 CaCO3 → CaO + CO2 (1) 4

M2 thermal decomposition (1)

M3 SiO2 + CaO → CaSiO3 (1)

M4 acid-base reaction (1)

3(d)(i) alloy 1

3(d)(ii) nickel / chromium 1

3(e) hydrated iron(III) oxide 1

3(f)(i) galvanising 1

3(f)(ii) painting / greasing / coating with plastic 1

3(f)(iii) M1 zinc more reactive (than iron) (1) 2

M2 zinc corrodes / oxidises / reacts in preference to / instead of iron (1)

Question Answer Marks

4(a)(i) M1 lead nitrate (1) 2

M2 soluble chloride e.g. sodium chloride (1)

4(a)(ii) Pb2+(aq) + 2Cl–(aq) → PbCl2(s) 3

M1 PbCl2 as only product (1)

M2 Pb2+ + 2Cl– as only reactants (1)

M3 state symbols (1)

© UCLES 2023 Page 7 of 10

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

4(a)(iii) M1 filter (1) 3

M2 wash (the residue) using water (1)

M3 dry the residue between filter papers / in a warm place (1)

4(b)(i) mobile ions 1

4(b)(ii) 2Cl– → Cl2 + 2e– 2

M1 any negative Cl species losing electron(s) (1)

M2 correct ionic half equation (1)

4(b)(iii) M1 (damp) litmus (paper) (1) 2

M2 is bleached / goes white (1)

4biv (shiny) grey AND solid 1

Question Answer Marks

5(a) enthalpy change (of reaction) 1

5(b)(i) M1 rate of reaction increases (1) 3

M2 more (CCl4) particles per unit volume (1)

M3 frequency of collisions between (CCl4 and H2O) particles increases (1)

5(b)(ii) M1 (position of) equilibrium moves to left hand side (1) 2

M2 more (gaseous) moles / molecules on right hand side (1)

© UCLES 2023 Page 8 of 10

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

5(b)(iii) M1 Labels mark 3

CCl4(g) + 2H2O(g) on reactant line
AND
CO2(g) + 4HCl(g) on product line

M2 Activation E mark
upward arrow labelled Ea from energy level of reactants to top of ‘hump’

M3 Energy change mark

one downward arrow labelled H
AND
energy change starting from E level of reactants and finishing at E level of products

5(b)(iv) M1 minimum energy (1) 2

M2 that colliding particles must have to react (1)

5(b)(v) (decreased by adding) catalyst 1

5(c) energy needed to break bonds in reactants 4

M1 [(4  340) + (4  460) = 3200 (kJ / mol) (1)

energy released when bond in carbon dioxide form

M2 2  805 = 1610 (kJ / mol) (1)

calculate H–Cl bond energy

M3 3200 – (1610 + E(4H–Cl)) = – 130
E(4H–Cl) = 3330 – 1610 = 1720 (kJ / mol) (1)

M4 1720 / 4 = 430 (kJ / mol) (1)

© UCLES 2023 Page 9 of 10

0620/42 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

6(a) M1 (same) general formula (1) 2

M2 (contain the same) functional group (1)

6(b) -CH2- unit 1

M1 alkenes (1) 3
6(c)(i)
M2 alkanes (1)

M3 carboxylic acids (1)

6(c)(ii) M1 propanoic acid (1) 2

M2 displayed formula of propanoic acid (1)

6(d)(i) M1 working to give the mass of atoms shown in Fig 6.1 2

103 – 14 – (2  12) – (2  16) – (4  1)
(= 29)

M2 ‘R’ = C2H5

6(d)(ii) proteins 1

© UCLES 2023 Page 10 of 10

Cambridge IGCSE™

CHEMISTRY 0620/43
Paper 4 Theory (Extended) October/November 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 October/November 2023 series for most
Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level
components.

This document consists of 11 printed pages.

© UCLES 2023 [Turn over

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED

Question Answer Marks

1(a) potassium iodide 1

1(b) sodium bromide 1

1(c) sulfur dioxide 1

1(d) propene 1

1(e) carbon monoxide 1

1(f) anhydrous copper(II) sulfate 1

Question Answer Marks

2(a)(i) A, B, F 1

2(a)(ii) D 1

2(a)(iii) C 1

2(b) 5 1

2(c) 33 1

2(d) 2,8,8 1

2(e) 5 1

2(f) 2 1

© UCLES 2023 Page 5 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

3(a)(i) 78 1

3(a)(ii) natural gas 1

3(a)(iii) M1 three single bonding pairs containing one dot and one cross (1) 2

M2 two dots or two crosses on N (and no additional electrons on Hs) to complete the outer shell on N and all 3 Hs (1)

3(a)(iv) M1 N2 + 3H2 → 2NH3 (1) 5

M2 ⇌ (1)

M3 450 °C (1)

M4 200 atmospheres / 20 000 kPa (1)

M5 iron (1)

3(b)(i) platinum 1

3(b)(ii) M1 –3 (1) 2

M2 +2 (1)

3(b)(iii) oxidation AND oxidation number increases 1

3(b)(iv) 4
M1 increase (1) M4 decrease (1)

M2 increase (1)

M3 no change (1)

© UCLES 2023 Page 6 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

3(b)(v) M1 kinetic energy of particles is lower (1) 3

M2 frequency of collisions between particles is lower (1)

M3 fewer / lower percentage / lower proportion / lower fraction of particles have energy greater than / equal to activation
energy
OR
fewer / lower percentage / lower fraction of collisions have energy greater than / equal to activation energy (1)

3(c) 4NO + 3O2 + 2H2O → 4HNO3 1

Question Answer Marks

4(a)(i) dilute sulfuric acid 1

4(a)(ii) M1 solid remains / solid undissolved (1) 2

M2 bubbling / effervescence / fizzing stops (1)

4(a)(iii) aqueous zinc sulfate 1

4(a)(iv) any two 2

• zinc oxide
• zinc carbonate
• zinc hydroxide

4(b)(i) M1 (a solution containing the) maximum amount of solute dissolved / no more solute can dissolve (1) 2

M2 at a given temperature (1)

4(b)(ii) solubility decreases as temperature decreases 1

4(c)(i) hydrated 1

4(c)(ii) to ensure all the water of crystallisation is removed 1

© UCLES 2023 Page 7 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

4(c)(iii) M1 2  10-3 / 0.002 (1) 4

M2 0.144 (g) (1)

M3 (0.144  18 = ) 8  10-3 / 0.008 (1)

M4 (0.008  0.002 = ) 4 (1)

Question Answer Marks

5(a)(i) M1 positive ions / cations (1) 3

M2 sea of electrons / mobile electrons / delocalised electrons (1)

M3 attraction between positive ions and electrons (1)

5(a)(ii) electrons move / electrons mobile / electrons flow 1

5(b)(i) any two 2

• (coke) releases heat
• (coke) reduces iron(III) oxide
• (coke) reacts with carbon dioxide to form carbon monoxide

5(b)(ii) M1 limestone decomposes to calcium oxide (1) 2

M2 calcium oxide reacts with / neutralises silicon(IV) oxide to produce slag / calcium silicate (1)

© UCLES 2023 Page 8 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

5(b)(iii) Fe2O3 + 3C → 2Fe + 3CO 2

OR

Fe2O3 + 3CO → 2Fe + 3CO2

OR

2Fe2O3 + 3C → 4Fe + 3CO2

M1 all formulae (1)

M2 equation correct (1)

5(b)(iv) temperature in the furnace is above the melting point of iron 1

5(c) M1 atoms have different sizes (1) 2

M2 layers cannot slide over or past each other (1)

5(d)(i) oxygen AND water 1

5(d)(ii) galvanising 1

5(d)(iii) acts as a barrier which prevents oxygen and water reaching the iron 1

5(d)(iv) M1 zinc is more reactive than iron (1) 2

M2 zinc is oxidised / zinc loses electrons / zinc forms positive ions / forms zinc ions (1)

© UCLES 2023 Page 9 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

6(a) any two 2

• general formula
• functional group
• chemical properties

6(b) ethyl propanoate 1

6(c)(i) M1 propan-1-ol (1) 2

M2 methanoic acid (1)

6(c)(ii) C4H8O2 1

6(d) C2H4O 1

6(e)(i) condensation 1

© UCLES 2023 Page 10 of 11

0620/43 Cambridge IGCSE – Mark Scheme October/November 2023
PUBLISHED
Question Answer Marks

6(e)(ii) 2

M1
2 –COOH groups fully displayed (1)

M2

2 –NH2 groups fully displayed (1)

6(f)(i) proteins 1

6(f)(ii) amino acids 1

© UCLES 2023 Page 11 of 11