Cambridge International AS & A Level
CHEMISTRY 9701/44
Paper 4 A Level Structured Questions May/June 2025
MARK SCHEME
Maximum Mark: 100
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 2025 series for most
Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level
components.
This document consists of 17 printed pages.
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9701/44 Cambridge International AS & A Level – Mark Scheme May/June 2025
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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 descriptions 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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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 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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Annotations guidance for centres
Examiners use a system of annotations as a shorthand for communicating their marking decisions to one another. Examiners are trained during the
standardisation process on how and when to use annotations. The purpose of annotations is to inform the standardisation and monitoring
processes and guide the supervising examiners when they are checking the work of examiners within their team. The meaning of annotations and
how they are used is specific to each component and is understood by all examiners who mark the component.
We publish annotations in our mark schemes to help centres understand the annotations they may see on copies of scripts. Note that there may
not be a direct correlation between the number of annotations on a script and the mark awarded. Similarly, the use of an annotation may not be an
indication of the quality of the response.
The annotations listed below were available to examiners marking this component in this series.
Annotations
Annotation Meaning
Correct point or mark awarded
Incorrect point or mark not awarded
Unclear
Information missing or insufficient for credit
Benefit of the doubt given
Contradiction in response otherwise markworthy, mark not given
Part of the correct answer has been seen. Full credit has not been awarded.
Error carried forward applied
Incorrect or insufficient point ignored while marking the rest of the response
Benefit of the doubt not applied in this instance
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Annotation Meaning
Rounding error
Repetition
Blank page or part of script seen
Error in number of significant figures
Transcription error
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Question Answer Marks
1(a)(i) M1: (thermal stability) increases (down the group or from Mg to Ba) 3
OR carbonates become more stable (down the group or from Mg to Ba)
M2: ion / cation size / radius increases OR charge density on ion / cation decreases
M3: less polarised CO3(2)– / anion / carbonate ion
OR weakens the C-O / C=O / covalent bonds less
OR weakens bonds in the anion less
OR lattice enthalpy of MO falls (less exothermic) faster than MCO3 (due to differing sizes of anions)
1(a)(ii) CuCO3 ⎯⎯→ CuO + CO2 1
1(b)(i) 1
[Ar] ↿⇂ ↿⇂ ↿⇂ ↿⇂ ↿
1(b)(ii) 1
1(b)(iii) the (3)d and (4)s are close / similar in energy 1
1(c)(i) M1: species with / has two lone pairs of electrons 2
M2: that form dative (covalent) / co-ordinate bond(s) to a (central) transition-element / metal AND atom / ion
OR donates electron pair(s) to a (central) transition-element / metal AND atom / ion
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Question Answer Marks
1(c)(ii) 3
each correct structure = [1]
1(c)(iii) optical AND geometrical / cis-trans 1
1(c)(iv) identification of either cis isomer AND dipoles / polar bonds / partial charges do not cancel 1
OR identification of either cis isomer AND it is asymmetric and has polar bonds
1(d)(i) 1
complex ion in Na3Al F6 Al F63–
ligand in Na3Al F6 F–
1(d)(ii) M1: charge passed = 1.5 30 60 OR 2700 (C) 4
M2: n(e–) = 2700 / 96500 OR 2.80 10–2 (mol)
M3: n(Al) = 2.80 10-2 ÷ 3 OR 9.33 10–3 (mol)
M4: mass (Al) = (27 9.33 10-3) = 0.25 (g)
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Question Answer Marks
2(a)(i) white / steamy fumes 1
2(a)(ii) number of (possible) arrangements of particles AND energy in a system 1
2(a)(iii) due to the large number increase in gas molecules formed (in the reaction) 1
OR there are much more gaseous molecules in the products
OR six gas moles are produced
2(a)(iv) M1: Hr = (–859) + (2 x –297) + (4 x –92) – (–1460) – (2 x –246) OR +131 kJ mol–1 3
M2: use of G = H – TS AND use of 298 (or 273+25) for T
M3: G = 131 – (298 x 0.768) = –97.9 (kJ mol–1)
2(b)(i) 2Ba2+(aq) + Cr2O72-(aq) + H2O(l) ⎯⎯→ 2BaCrO4(s) + 2H+(aq) 1
2(b)(ii) M1: d orbital(s) of two different energies / d-d splitting occurs 3
OR d orbital(s) / d (sub)-shell splits / d-d gap
OR (inferred from movement of an electron) from lower d to higher d orbital
M2: electron(s) promoted / excited
OR electron(s) moves to higher (d–) orbital
OR electron(s) jumps up (to d– orbital) / jumps to higher (d–orbital)
M3: wavelength / frequency / light / photon / h / hf absorbed
OR radiation / energy from visible (region) absorbed AND colour (seen) is complementary
OR wavelength / frequency / colour / light not absorbed is transmitted / reflected / seen
2(c) M1: Hlatt and Hhyd decrease / both become less exothermic / less negative 3
M2: Hhyd changes more / dominant factor / changes faster
OR Hlatt changes less / becomes less exothermic by a smaller extent
M3: Hsol becomes less exothermic / less negative
OR Hsol becomes (more) endothermic / (more) positive
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Question Answer Marks
3(a)(i) M1: Ksp = [Ni2+][IO3–]2 2
M2: units: mol3 dm–9
3(a)(ii) [Ni2+] = 2.3 10–2; [IO3–] = 4.6 10–2 1
Ksp = (2.3 10–2) (4.6 10-2)2 = 4.87 10–5
3(b)(i) Eocell = 1.19 – (0.34) = (+)0.85 (V) AND (positive electrode is) right hand side / nickel electrode / platinum / iodate 1
3(b)(ii) (Ecell would be) less positive / more negative AND as [IO3–] is less than 1.0 mol dm–3 / has a lower / smaller concentration 1
3(b)(iii) M1: Ecell is less positive ticked 2
M2: [IO3–(aq)] is lowered due to the common ion effect
OR Ni(IO3)2 precipitating or shown by equation
OR solubility of Ni(IO3)2 decreasing
3(c)(i) [H+] = 10–pH = 10–0.47 = 0.34 / 0.339 (mol dm-3) min 2sf 1
3(c)(ii) [HIO3]eqm = 1.0 – 0.34 = 0.66 (mol dm–3) min 2sf 1
AND [H+]eqm = [IO3–]eqm = 0.34 (mol dm–3) min 2sf
3(c)(iii) Ka = (0.34)2 / 0.66 = 0.17– 0.18 (mol dm–3) min 2sf 1
3(d)(i) M1: opposes / resists change in pH / controls pH / pH kept within a small range 2
M2: when small amount of acid / H+ or alkali / base / OH– is added
3(d)(ii) M1: k = {2.1 10–2}/{0.5 (1 10–3)2 0.012} = 4.20 108 min 2sf 2
M2: mol–4 dm12 s–1
3(d)(iii) rate will be (0.03 / 0.01)2 = 9 times as fast, so rate = 9 2.1 10–2 1
= 0.19 (0.189) (mol dm–3 s–1) min 2sf
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Question Answer Marks
4(a) 4
polymer type of polymerisation structure of monomer
X condensation H2(CH2)5CO2H
OR NH2(CH2)5COCl
Y addition CH2=CHCO2CH3
Z condensation CH3CH(OH)CO2H
OR CH3CH(OH)COCl
Type of polymerisation (all three) = [1]
Structure of monomers = [1] for each structure
4(b) pH (where) the species is a zwitterion (is the dominant form) 1
OR pH (where) the species is (electrically) neutral
OR pH (where) the species has a (net overall) charge of zero
4(c)(i) Glu Lys 2
Gly
+ -
Start point
M1: Gly correct
M2: Glu and Lys correct
4(c)(ii) it would move towards the positive terminal / anode / side / end or to the left 1
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Question Answer Marks
5(a)(i) 1
5(a)(ii) the OH / NH groups / O atoms AND can hydrogen bond with water 1
5(a)(iii) C33H35N2O5F 1
5(a)(iv) 1
5(a)(v) different / better biological activity 1
5(b)(i) 16 / sixteen 1
5(b)(ii) M1: 4 / four 2
M2: proton exchange between NH / OH with D
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Question Answer Marks
5(c) groups reacting 2
• carboxylic acid
• amide
groups forming
• (primary) alcohol
• amine
Any two [1] all four [2]
Question Answer Marks
6(a) 4
test
I2(aq) warm with
sodium
Na2CO3(aq) 2,4-DNPH + Fehling’s Br2(aq)
metal
OH–(aq) solution
alcohol / carboxylic carbonyl / (methyl) aldehyde alkene
carboxylic acid ketone / ketone / (
acid aldehyde methyl)
alcohol
Any two [1] any three [2] any five [3] all six [4]
6(b)(i) (primary) alcohol 1
6(b)(ii) M1: A → B oxidation/dehydrogenation 3
M2: C → E reduction/(nucleophilic) addition
M3: E → F elimination/dehydration
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Question Answer Marks
6(b)(iii) 2
each correct structure [1]
6(b)(iv) 5
D F E C
A any one of the following
each correct structure [1]
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Question Answer Marks
7(a) M1: benzoic acid > phenol > ethanol 3
M2 / M3: any two [1] any three [2]
• correct link of acidity once AND weakens O—H / OH bond / hydroxyl bond / -O-H
OR H+ more easily lost / (carboxylate) anion stabilised u / c
• (benzoic acid) due to negative inductive effect / electron withdrawing effect AND of C=O / COOH / carboxyl
• (phenol) as lone pair / p-orbital (electrons) on oxygen (on phenol) / AND overlap / delocalised into the ring / π-system
• (ethanol) alkyl / ethyl / R group AND is electron donating / positive inductive effect
7(b) 2
Each correct structure = [1]
7(c)(i) ethyl propanoate 1
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Question Answer Marks
7(c)(ii) 4
M1 / M2: any two [1] all four [2]
• lone pair on O
• correct arrow from (lone pair) O to C (of C=O)
• dipole on C=O
• correct arrow on C=O
M3: correct intermediate
M4: arrow from lone pair or charge on O– to C-O bond AND arrow from C-Cl to Cl
7(c)(iii) (nucleophilic) addition – elimination 1
Question Answer Marks
8(a)(i) M1: energy change / released when 1 mole of a (ionic) solid / lattice / crystal / compound is formed 2
M2: from gas (phase) ions / gaseous ions (under standard conditions)
8(a)(ii) (enthalpy change when) 1 mole of a substance / solid / solute / molecule AND dissolves in water (to give a solution of infinite 1
dilution)
8(b) Hsol(NaCl) = Hhyd(Na+) + Hhyd(Cl –) – Hlatt(NaCl) 1
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Question Answer Marks
8(c) 3
M1 / M2: any two [1] all four [2]
M3: all state symbols for the formula are present and correct
8(d) M1: (more exothermic because) Cl– OR NO3– because its (ionic) radius / size is smaller 2
M2: (more exothermic because) (ion-dipole) attraction / bond between it and water is stronger
OR
M1: NO3– because it has lone pairs on O / more lone pairs
M2: which can form hydrogen bonds with water
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