GATEWAY-SCIENCE-CHEMISTRY-A-J248 · Cambridge OCR GCSE (9–1)
GATEWAY-SCIENCE-CHEMISTRY-A-J248/31
(Higher Tier) - Topics C1-C3 and C7
Gateway Science Chemistry A · June 2023 · Variant 1
Relative difficulty
Analysis source: OCR
Analysis aligned to the official syllabus and assessment design.
3.5 / 5
180
210 min
Alkanes, Alkenes, Combustion and Cracking
Cohort performance
Session statistics from official examination reports
Total marks
180
Duration
210 min
Session difficulty
3.5 / 5
Key examiner messages
Top priorities from the principal examiner before you revise
Many marks were readily accessible on core topics like atomic structure, state changes, and identification of simple separation apparatus.
However, higher-ability candidates were differentiated by complex stoichiometry.
Major mark drops occurred in Paper 3 Q22 (calculating the mass of oxygen and molecules of nitrogen dioxide from moles) and Paper 4 Q23 (determining acid concentration in g/dm3 g/dm^3 g/dm3 after a titration calculation).
Forgetting to apply the unit conversions between cm3 cm^3 cm3 and dm3 dm^3 dm3 proved fatal for otherwise solid working.
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.
Mathematical Conversion
Weight: 4100%Scientific Explanation
Weight: 375%Recall & knowledg
Weight: 250%Graphical Analysis
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
Examiner report — national grade boundaries and question-level commentary
Level 9
Approx. 82% of maximum mark
Level 8
Approx. 73% of maximum mark
Level 7
Approx. 64% of maximum mark
Level 6
Approx. 53% of maximum mark
Level 5
Approx. 43% of maximum mark
Level 4
Approx. 33% of maximum mark
Level 3
Approx. 28% 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
Show formula, substitution, and unit; method marks need visible working.
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.
Match the expected response style for “State” questions.
Match the expected response style for “Write” questions.
Match the expected response style for “Predict” questions.
Weigh arguments for and against with evidence; end with a supported judgement.
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
Organic chemistry
32 marks this session
Introducing chemical reactions
25 marks this session
Purity and separating mixtures
12 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
Introducing chemical reactions
Organic chemistry
Bonding
Predicting chemical reactions
Improving processes and products
Purity and separating mixtures
Difficulty trend
How session difficulty has shifted across recent years
Paper comparison
Marks and duration breakdown across papers in this session
J248/03 (Higher
Paper 3): J248/04 (Higher
Paper 4):
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
Organic chemistry
32 marks this session
Practise in RevuiIntroducing chemical reactions
25 marks this session
Practise in RevuiPurity and separating mixtures
12 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
Many marks were readily accessible on core topics like atomic structure, state changes, and identification of simple separation apparatus.
- 2Message
However, higher-ability candidates were differentiated by complex stoichiometry.
- 3Message
Major mark drops occurred in Paper 3 Q22 (calculating the mass of oxygen and molecules of nitrogen dioxide from moles) and Paper 4 Q23 (determining acid concentration in g/dm3 g/dm^3 g/dm3 after a titration calculation).
- 4Message
Forgetting to apply the unit conversions between cm3 cm^3 cm3 and dm3 dm^3 dm3 proved fatal for otherwise solid working.
Teacher briefing pack
One-page session summary for tutors and classroom review
June 2023 2023
Gateway Science Chemistry A
Many marks were readily accessible on core topics like atomic structure, state changes, and identification of simple separation apparatus. However, higher-ability candidates were differentiated by complex stoichiometry. Major mark drops occurred in Paper 3 Q22 (calculating the ma
Many marks were readily accessible on core topics like atomic structure, state changes, and identification of simple separation apparatus.
However, higher-ability candidates were differentiated by complex stoichiometry.
Major mark drops occurred in Paper 3 Q22 (calculating the mass of oxygen and molecules of nitrogen dioxide from moles) and Paper 4 Q23 (determining acid concentration in g/dm3 g/dm^3 g/dm3 after a titration calculation).
- Total marks
- 180
- Duration
- 210 min
- Session difficulty
- 3.5 / 5
Session analysis
Many marks were readily accessible on core topics like atomic structure, state changes, and identification of simple separation apparatus. However, higher-ability candidates were differentiated by complex stoichiometry. Major mark drops occurred in Paper 3 Q22 (calculating the mass of oxygen and molecules of nitrogen dioxide from moles) and Paper 4 Q23 (determining acid concentration in g/dm3 g/dm^3 g/dm3 after a titration calculation). Forgetting to apply the unit conversions between cm3 cm^3 cm3 and dm3 dm^3 dm3 proved fatal for otherwise solid working.
Updated Jun 14, 2026
Paper breakdown
J248/03 (Higher
Paper 3): J248/04 (Higher
Paper 4):
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.
78% 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.
Structured Short Answer
92·48·51%
Mathematical/Calculation
46·14·26%
Multiple Choice
(MCQ)
30·30·17%
Level of Response
(LOR)
12·2·7%
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.
Bond energy calculations
85%85%
Rusting prevention and barrier methods
75%75%
Examiner notes & key calculations
- Catalyst Misconceptions: In Paper 4 Q21(b), a significant number of candidates incorrectly stated that a catalyst shifts the position of equilibrium to the right rather than accelerating both rates equally.
- Graphite vs. Nanotubes: When comparing carbon allotropes, candidates often refer to "weak covalent bonds" instead of distinguishing between strong covalent bonds within sheets and weak intermolecular forces between layers.
- Aqueous Electrolysis Rules: Explaining which ion is discharged at the cathode in aqueous copper sulfate remains a key obstacle for many students.
Exam tips
Paper format
- Duration
- 1h 45min
- Total marks
- 90
- Weighting
- 50%
- Question types
- Multiple Choice, Structured / Mathematical Calculation, Structured / Descriptive Short-Answer, Extended Response (* - Level of Response)
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.