CHEMISTRY · HKDSE
CHEMISTRY/21
(Elective Part)
Chemistry · 2021 · Variant 1
Relative difficulty
Analysis source: Hong Kong Examinations and Assessment Authority (HKEAA)
Analysis aligned to the official syllabus and assessment design.
3.8 / 5
160
210 min
Electrolysis and Electrochemistry
Cohort performance
Session statistics from official examination reports
Total marks
160
Duration
210 min
Session difficulty
3.8 / 5
Level 5**
~92% of max
Level 5*
~85% of max
Level 5
~78% of max
Key examiner messages
Top priorities from the principal examiner before you revise
The 2021 HKDSE Chemistry exam was highly comprehensive, with an emphasis on experimental design, precise observational terminology in electrochemistry, and structured multi-step calculations in thermodynamics and volumetric analysis.
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.
Conceptual Explanation
Weight: 7100%Quantitative
Weight: 571%Experimental
Weight: 457%Organic
Weight: 343%Structura
Weight: 229%Analysis & G
Weight: 114%
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
Reporting source
HKEAA Subject Examination Report — comments on candidates’ performance with marking schemes
Level 5**
Outstanding — competitive JUPAS programmes (medicine, law, top faculties)
Level 5*
Excellent — strong JUPAS profile for selective programmes
Level 5
Good — meets most university entrance requirements
Level 4
Satisfactory — foundation programmes or less selective routes
Level 3
Pass threshold for many sub-degree and vocational pathways
Admission context
Levels feed JUPAS and non-JUPAS university applications; 5** and 5* are most selective
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
Give reasons and link mechanism to outcome; each point needs a because/so chain.
Show formula, substitution, and unit; method marks need visible working.
Match the expected response style for “State” questions.
Apply knowledge to an unfamiliar context; concise, practical points score best.
Match the expected response style for “Draw” questions.
Match the expected response style for “Deduce” questions.
Match the expected response style for “Write” questions.
Time traps
Sections where candidates spent disproportionate time relative to marks
Min per mark: 1.5
Min per mark: 1.5
Min per mark: 1.3
Min per mark: 1.3
Syllabus traceability
Topics linked to questions and mark weighting in this session
Redox Reactions, Chemical Cells & Electrolysis
19 marks this session
Homologous series; naming; addition polymerisation
14 marks this session
Reactivity series, displacement, extraction methods
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
Enthalpy changes; Hess’s Law; energy cycles
Redox Reactions, Chemical Cells & Electrolysis
Reactions of Carbon Compounds (Inter-conversions)
Isomerism & Chemistry of Carbon Compounds
Homologous series; naming; addition polymerisation
Metals (Reactivity, displacement, extraction)
Reactions and Inter-conversions of Carbon Compounds
Instrumental analytical methods (Analytical Chemistry)
Difficulty trend
How session difficulty has shifted across recent years
Paper comparison
Marks and duration breakdown across papers in this session
Paper 1 (Section A & B):
Paper 2 (Section A Industrial & Section C Analytical):
Marks you can still earn
Where valid approaches outside the mark scheme may still gain credit
- Believing that adding a catalyst decreases the overall activation energy of the primary pathway, rather than providing an alternative reaction pathway of lower activation energy.
Practise what examiners flagged
Target weak topics from this report inside the Revui app
Redox Reactions, Chemical Cells & Electrolysis
19 marks this session
Practise in RevuiHomologous series; naming; addition polymerisation
14 marks this session
Practise in RevuiReactivity series, displacement, extraction methods
12 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
The 2021 HKDSE Chemistry exam was highly comprehensive, with an emphasis on experimental design, precise observational terminology in electrochemistry, and structured multi-step calculations in thermodynamics and volumetric analysis.
Teacher briefing pack
One-page session summary for tutors and classroom review
2021 2021
Chemistry
The 2021 HKDSE Chemistry exam was highly comprehensive, with an emphasis on experimental design, precise observational terminology in electrochemistry, and structured multi-step calculations in thermodynamics and volumetric analysis.
The 2021 HKDSE Chemistry exam was highly comprehensive, with an emphasis on experimental design, precise observational terminology in electrochemistry, and structured multi-step calculations in thermodynamics and volumetric analysis.
- Total marks
- 160
- Duration
- 210 min
- Session difficulty
- 3.8 / 5
- Level 5**
- ~92% of max
- Level 5*
- ~85% of max
- Level 5
- ~78% of max
Session analysis
The 2021 HKDSE Chemistry exam was highly comprehensive, with an emphasis on experimental design, precise observational terminology in electrochemistry, and structured multi-step calculations in thermodynamics and volumetric analysis.
Updated Jun 11, 2026
Paper breakdown
Paper 1 (Section A & B):
Paper 2 (Section A Industrial & Section C Analytical):
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.
Paper 1B)
84·13·53%
Paper 2)
40·2·25%
160marksMultiple Choice
(MC)
36·36·23%
Study ROI
Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.
Time vs marks
Compare marks with suggested time allocation to plan exam pacing.
Paper 1 Section A (…
0.80 m/minPaper 1 Section B P…
0.80 m/minPaper 1 Section B P…
0.67 m/minPaper 2 Section A (…
0.67 m/minTotal marks
124
Total time
165 min
Avg pace
0.75
Next-year prediction
Topics worth watching next year, with the reason shown directly below each bar.
Green Chemistry & Atom Economy in Industrial Processes
88%88%
Transition Metals as Catalysts & Ligand Complexation
85%85%
Structure and Properties of Soaps vs Detergents
82%82%
Enthalpy Changes & Calorimeter Heat Loss Corrections
80%80%
Exam tips
Paper format
- Duration
- 1h
- Total marks
- 40
- Weighting
- 20%
- Question types
- Structured/Calculation Questions
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.