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100+ Free HKDSE Chemistry Practice Questions

Pass your Hong Kong Diploma of Secondary Education (HKDSE) Chemistry exam on the first try — instant access, no signup required.

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Question 1
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In a flame test, a lilac (pale purple) flame colour indicates the presence of which metal ion?

A
B
C
D
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2026 Statistics

Key Facts: HKDSE Chemistry Exam

HKDSE Chemistry is assessed by Paper 1 (compulsory, 60%, 2.5 hours, MCQ plus structured/essay), Paper 2 (electives, 20%, 1 hour) and SBA (20%), graded on a 7-level scale from 5** to 1 plus U.

Sample HKDSE Chemistry Practice Questions

Try these sample questions to test your HKDSE Chemistry exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which gas makes up approximately 78% by volume of dry air on Earth?
A.Oxygen
B.Argon
C.Carbon dioxide
D.Nitrogen
Explanation: Dry air is roughly 78% nitrogen and 21% oxygen by volume, with argon (~0.9%) and carbon dioxide (~0.04%) making up most of the remainder. Nitrogen is the most abundant component of the atmosphere.
2Sea water contains dissolved ions. Which ion is present in the highest concentration in sea water?
A.Sodium ion
B.Chloride ion
C.Magnesium ion
D.Sulfate ion
Explanation: Chloride ion (Cl-) is the most abundant ion in sea water by mass and concentration, followed by sodium ion (Na+). Together they form the dissolved sodium chloride that gives sea water its salinity.
3Limestone is a mineral mainly composed of which compound?
A.Calcium oxide
B.Calcium hydroxide
C.Calcium carbonate
D.Calcium sulfate
Explanation: Limestone consists mainly of calcium carbonate (CaCO3). On strong heating it decomposes to calcium oxide (quicklime) and carbon dioxide, a reaction important in industry.
4An atom of an element has 17 protons, 18 neutrons and 17 electrons. What is the mass number of this atom?
A.17
B.18
C.35
D.52
Explanation: Mass number equals the number of protons plus neutrons. Here 17 protons + 18 neutrons = 35. This atom is chlorine-35, the more abundant isotope of chlorine.
5What is the electronic arrangement of a magnesium atom (atomic number 12)?
A.2,8,2
B.2,8,8
C.2,2,8
D.8,2,2
Explanation: Magnesium has 12 electrons. Filling shells in order gives 2 in the first shell, 8 in the second, and 2 in the third: 2,8,2. The two outermost electrons explain why magnesium forms Mg2+ ions.
6Which type of bonding holds the ions together in solid sodium chloride?
A.Covalent bonding
B.Metallic bonding
C.Ionic bonding
D.Hydrogen bonding
Explanation: Sodium chloride is held together by ionic bonding, the electrostatic attraction between positive Na+ ions and negative Cl- ions arranged in a giant ionic lattice. This explains its high melting point and conductivity when molten.
7How many electrons are shared in total between the two oxygen atoms in an oxygen molecule (O2)?
A.Two
B.Eight
C.Six
D.Four
Explanation: An oxygen molecule contains a double covalent bond, which consists of two shared pairs of electrons, i.e. four electrons in total. Each oxygen atom contributes two electrons to the double bond.
8Which of the following best explains why diamond has an extremely high melting point?
A.It has weak van der Waals forces between molecules
B.It contains delocalised electrons that bind the lattice
C.It is a giant covalent structure with strong covalent bonds throughout
D.It is held together by ionic bonds
Explanation: Diamond is a giant covalent (macromolecular) structure in which every carbon atom is bonded to four others by strong covalent bonds. Melting requires breaking many strong covalent bonds, giving it a very high melting point.
9Graphite can conduct electricity because it has
A.mobile ions in the lattice
B.delocalised electrons between the layers
C.a giant ionic structure
D.weak covalent bonds that break easily
Explanation: In graphite each carbon forms three covalent bonds, leaving one delocalised electron per atom. These delocalised electrons move freely between the layers, allowing graphite to conduct electricity.
10Metallic bonding is best described as the attraction between
A.positive metal ions and a sea of delocalised electrons
B.positive and negative ions
C.shared pairs of electrons between atoms
D.permanent dipoles in molecules
Explanation: Metallic bonding is the electrostatic attraction between a regular lattice of positive metal ions and a 'sea' of delocalised valence electrons. These mobile electrons explain why metals conduct electricity and heat.

About the HKDSE Chemistry Exam

HKDSE Chemistry is the senior-secondary chemistry examination taken by Hong Kong students at the end of Secondary 6, administered by the HKEAA. Public assessment comprises Paper 1 (Compulsory, 60%, 2 hours 30 minutes) with a multiple-choice Section A (18%) and a short/structured/essay Section B (42%), Paper 2 (Elective, 20%, 1 hour) of structured questions on 2 of 3 electives, and School-based Assessment (20%). The compulsory curriculum spans 12 topics from Planet Earth and Microscopic World through Metals, Acids and Bases, Fossil Fuels and Carbon Compounds, Redox/Electrochemistry, Energetics, Rate, Equilibrium and Patterns in the Chemical World. The three electives are Industrial Chemistry, Materials Chemistry and Analytical Chemistry, with green chemistry as a recurring theme. Results are reported on a 7-level scale from 5** down to 1, plus U, and the subject is used for local and overseas university admission.

Questions

100 scored questions

Time Limit

Paper 1: 2 hours 30 minutes; Paper 2: 1 hour

Passing Score

7-level grading: 5**, 5*, 5, 4, 3, 2, 1, U. Level 3 is the common benchmark for university and further-study eligibility.

Exam Fee

2026 subject fee: HK$519 (school candidate), HK$1,119 (private candidate with Permanent HKIC), HK$1,377 (private candidate without Permanent HKIC). (Hong Kong Examinations and Assessment Authority (HKEAA))

HKDSE Chemistry Exam Content Outline

30%

Planet Earth, Microscopic World and Metals

Atmosphere and sea water, minerals, atomic structure, ionic/covalent/metallic bonding, structures and properties, metal reactivity, extraction, corrosion and alloys.

25%

Acids, Bases and Carbon Compounds

pH, titration, salts, fossil fuels, homologous series, alkanes, alkenes, isomerism, alcohols, carboxylic acids, esters and polymers.

20%

Redox, Electrochemistry and Energetics

Oxidation numbers, redox reactions, chemical cells, electrolysis, enthalpy changes and Hess's law.

15%

Rate, Equilibrium and Patterns

Collision theory, catalysts, dynamic equilibrium, Le Chatelier's principle, periodic trends and the Haber and Contact processes.

10%

Electives (Industrial, Materials, Analytical Chemistry)

Industrial process design and green chemistry, polymers and composites, nanomaterials, chromatography, spectroscopy and qualitative analysis.

How to Pass the HKDSE Chemistry Exam

What You Need to Know

  • Passing score: 7-level grading: 5**, 5*, 5, 4, 3, 2, 1, U. Level 3 is the common benchmark for university and further-study eligibility.
  • Exam length: 100 questions
  • Time limit: Paper 1: 2 hours 30 minutes; Paper 2: 1 hour
  • Exam fee: 2026 subject fee: HK$519 (school candidate), HK$1,119 (private candidate with Permanent HKIC), HK$1,377 (private candidate without Permanent HKIC).

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

HKDSE Chemistry Study Tips from Top Performers

1Master mole calculations, balancing equations and titration arithmetic early; numerical questions appear across every topic.
2Practise Paper 1 Section A multiple-choice under timed conditions, allowing about 1 to 1.5 minutes per question.
3Learn the standard tests (gas tests, flame tests, halide and ion tests) and characteristic IR absorption ranges for the analytical elective.
4Use Le Chatelier's principle systematically to predict equilibrium shifts in the Haber and Contact processes.
5Build a one-page summary of functional groups and organic reaction types to revise carbon chemistry quickly.

Frequently Asked Questions

How is HKDSE Chemistry assessed?

Public assessment has three parts: Paper 1 (Compulsory, 60%, 2 hours 30 minutes) with multiple-choice Section A (18%) and short/structured/essay Section B (42%); Paper 2 (Elective, 20%, 1 hour) of structured questions on 2 of 3 electives; and School-based Assessment (20%).

How many compulsory topics are there?

There are 12 compulsory topics, from Planet Earth and Microscopic World through Metals, Acids and Bases, Fossil Fuels and Carbon Compounds, Redox/Electrochemistry, Energetics, Rate of Reaction, Chemical Equilibrium and Patterns in the Chemical World.

What are the elective options?

Candidates study 2 of 3 electives: Industrial Chemistry, Materials Chemistry and Analytical Chemistry. Green chemistry is introduced as a cross-cutting theme within the elective part.

How is HKDSE Chemistry graded?

Results are reported on a 7-level scale: 5** (highest), 5*, 5, 4, 3, 2 and 1, with U for unclassified. Level 3 is commonly treated as the benchmark for further study and university admission.

How much does it cost to sit HKDSE Chemistry in 2026?

The 2026 subject fee is HK$519 for school candidates, HK$1,119 for private candidates with a Permanent HKIC, and HK$1,377 for private candidates without a Permanent HKIC, with a HK$595 initial fee for private candidates.