0620 · Cambridge IGCSE
0620/61
Alternative to Practical
Chemistry · June 2025 · Variant 1
Relative difficulty
Analysis source: Cambridge Assessment International Education
Analysis aligned to the official syllabus and assessment design.
3.8 / 5
80
75 min
Reversible reactions and equilibrium
Cohort performance
Session statistics from official examination reports
Total marks
80
Duration
75 min
Session difficulty
3.8 / 5
Key examiner messages
Top priorities from the principal examiner before you revise
High-scoring candidates excelled on the standard descriptive sections, such as Atomic Structure and Isotopes in Question 2, and identifying Group VII properties in Question 6.
However, substantial marks were lost in the application of Le Chatelier's Principle to the methanol synthesis equilibrium (Question 5) and the correct determination of the mathematical sign in the bond energy enthalpy calculation (Question 6), where a final value of −7 kJ/mol-7\text{ kJ/mol}−7 kJ/mol required meticulous tracking of energy absorbed vs.
Question difficulty map
How candidates performed on each question in this series
No data available in official reports
Assessment objectives
Skill and AO weighting from official examiner commentary
Skill weighting
Shows the skill mix this paper tested most heavily.
Knowledge witAO2
Weight: 4100%Handling Information
Weight: 375%InfoAO3
Weight: 250%Experimental
Weight: 125%
Method marks watchlist
Where working, steps, or method marks were commonly lost
No data available in official reports
Recurring mistakes across years
Themes examiners flag in multiple recent sessions for this subject
No data available in official reports
Question choice intelligence
Mean scores and popularity for optional questions (HKDSE electives)
No data available in official reports
Level exemplars
What candidate scripts at each grade level looked like
No data available in official reports
Grade & admission context
How marks relate to grade thresholds and entry standards
Report type
Cambridge Principal Examiner Report — component performance and international standards
Level A*
Approx. 86% of maximum mark
Level A
Approx. 72% of maximum mark
Level B
Approx. 58% of maximum mark
Level C
Approx. 44% of maximum mark
Level D
Approx. 38% of maximum mark
Level E
Approx. 33% of maximum mark
Deep insights
What top candidates did
Techniques and approaches examiners rewarded in this series
No data available in official reports
Command word playbook
How to match each command word to the expected response style
Match the expected response style for “State” questions.
Give reasons and link mechanism to outcome; each point needs a because/so chain.
State features in sequence or list observable properties — do not explain causes unless asked.
Show formula, substitution, and unit; method marks need visible working.
Match the expected response style for “Deduce” questions.
Match the expected response style for “Draw” questions.
Time traps
Sections where candidates spent disproportionate time relative to marks
No data available in official reports
Syllabus traceability
Topics linked to questions and mark weighting in this session
Reversible reactions and equilibrium
11 marks this session
Preparation of salts
6 marks this session
Group VII properties
6 marks this session
MCQ trap analytics
Commonly chosen wrong options from examiner commentary
No data available in official reports
Topic heatmap across years
Mark concentration by topic and exam year for this subject
Mark intensity
Reversible reactions and equilibrium
Electrolysis
Atomic structure and the Periodic Table
Rate of reaction
Preparation of salts
Group VII properties
Difficulty trend
How session difficulty has shifted across recent years
Paper comparison
Marks and duration breakdown across papers in this session
Paper 41 Theory (Extended):
Marks you can still earn
Where valid approaches outside the mark scheme may still gain credit
No data available in official reports
Practise what examiners flagged
Target weak topics from this report inside the Revui app
Reversible reactions and equilibrium
11 marks this session
Practise in RevuiPreparation of salts
6 marks this session
Practise in RevuiGroup VII properties
6 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
High-scoring candidates excelled on the standard descriptive sections, such as Atomic Structure and Isotopes in Question 2, and identifying Group VII properties in Question 6.
- 2Message
However, substantial marks were lost in the application of Le Chatelier's Principle to the methanol synthesis equilibrium (Question 5) and the correct determination of the mathematical sign in the bond energy enthalpy calculation (Question 6), where a final value of −7 kJ/mol-7\text{ kJ/mol}−7 kJ/mol required meticulous tracking of energy absorbed vs.
Teacher briefing pack
One-page session summary for tutors and classroom review
June 2025 2025
Chemistry
High-scoring candidates excelled on the standard descriptive sections, such as Atomic Structure and Isotopes in Question 2, and identifying Group VII properties in Question 6. However, substantial marks were lost in the application of Le Chatelier's Principle to the methanol synt
High-scoring candidates excelled on the standard descriptive sections, such as Atomic Structure and Isotopes in Question 2, and identifying Group VII properties in Question 6.
However, substantial marks were lost in the application of Le Chatelier's Principle to the methanol synthesis equilibrium (Question 5) and the correct determination of the mathematical sign in the bond energy enthalpy calculation (Question 6), where a final value of −7 kJ/mol-7\text{ kJ/mol}−7 kJ/mol required meticulous tracking of energy absorbed vs.
- Total marks
- 80
- Duration
- 75 min
- Session difficulty
- 3.8 / 5
Session analysis
High-scoring candidates excelled on the standard descriptive sections, such as Atomic Structure and Isotopes in Question 2, and identifying Group VII properties in Question 6. However, substantial marks were lost in the application of Le Chatelier's Principle to the methanol synthesis equilibrium (Question 5) and the correct determination of the mathematical sign in the bond energy enthalpy calculation (Question 6), where a final value of −7 kJ/mol-7\text{ kJ/mol}−7 kJ/mol required meticulous tracking of energy absorbed vs. released.
Updated Jun 13, 2026
Paper breakdown
Paper 41 Theory (Extended):
Top chapters
Exam structure insights
Marks by chapter
See where the marks were concentrated so revision time goes to the highest-value topics.
Mark accessibility
Estimate which marks were basic, mid-level, or high-difficulty.
83% within easy or medium reach
Command word frequency
Spot common command words so answers match the expected response style.
Question type mix
Compare the mark share of each paper section and question type.
Descriptive & Structured
36·28·45%
Chemical Equations & Mechanism
18·10·23%
Identification & Multiple-Choice Style
16·10·20%
Calculations
10·4·13%
Study ROI
Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.
Next-year prediction
Topics worth watching next year, with the reason shown directly below each bar.
Electrolysis and Electrochemistry
95%95%
Polymers (Condensation polyesters & polyamides)
90%90%
Acid-Base Titrations and Volumetric Analysis
85%85%
Examiner notes & key calculations
- Metallic Bonding Descriptions: Many candidates failed to mention the electrostatic attraction between the positive metal cations and the sea of delocalised electrons, focusing only on the presence of mobile electrons.
- Precipitation and Salt Prep: In describing the copper(II) sulfate crystallisation, candidates frequently forgot to specify heating to the point of crystallisation (saturated solution) rather than evaporating to dryness.
- Oxidation States: Assigning the correct sign to oxidation numbers (e.g., −3-3−3 for nitrogen in ammonia) remains a persistent hurdle.
Exam tips
Paper format
- Duration
- 1h
- Total marks
- 40
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.