As you prepare for the NECO Chemistry exam in 2025/2026, it’s important to know the most repeated topics, questions, and answers in NECO Chemistry. Focusing on these frequently tested areas can help you understand what to expect and improve your chances of getting a top grade.
In this post, I’ll be showing you the most repeated NECO Chemistry topics, questions, and answers for the 2025/2026 exam. If you've been asking yourself questions like:
What are the most common NECO Chemistry questions?, What are the key topics in NECO Chemistry every year?, How can I study effectively for NECO Chemistry?, What are the most repeated NECO Chemistry theory and objective questions?, What is the area of concentration for Chemistry in NECO?, Where can I find NECO Chemistry past questions with answers?, Which topics appear yearly in NECO Chemistry?, Are there repeated questions in NECO Chemistry exams?, Can I pass Chemistry by studying only past questions?, and What are the most likely NECO Chemistry questions in 2025/2026? — then this guide is for you.
Why Study the Most Repeated NECO Chemistry Topics and Questions?
NECO Chemistry tests both theory and calculation-based scientific concepts. The exam covers atomic structure, chemical reactions, equations, organic chemistry, practicals, and more.
NECO often repeats Chemistry questions — either exactly or with minor variations. By focusing on these frequently repeated questions, you will:
Cover the most important areas of the syllabus
Understand how Chemistry questions are framed
Practice and master problem-solving techniques
Gain confidence for both theory and objective papers
This is the smart way to study. It saves time, boosts accuracy, and increases your exam score.
Most Repeated NECO Chemistry Topics (2025/2026)
These are the 15 most repeated topics in NECO Chemistry. Make them your priority:
1. Structure of the Atom
Atomic number and mass number
Isotopes
Electronic configuration
2. Periodic Table
Periodic law
Groups and periods
Periodic trends (ionization energy, atomic radius, electronegativity)
3. Chemical Bonding
Ionic, covalent, and metallic bonds
Properties of compounds based on bonding
4. Separation Techniques
Filtration, distillation, sublimation
Chromatography and fractional distillation
5. Chemical Reactions and Equations
Types of reactions
Writing and balancing equations
6. Acids, Bases and Salts
Properties and examples
pH scale
Preparation of salts
7. States of Matter and Gas Laws
Boyle’s, Charles’, and Ideal gas law
Kinetic theory of gases
8. Mole Concept and Stoichiometry
Avogadro’s number
Calculating moles, mass, volume, and concentration
9. Electrolysis
Electrolytes and non-electrolytes
Faraday’s laws
Electrochemical cells
10. Energy Changes in Reactions
Exothermic and endothermic reactions
Enthalpy change
11. Organic Chemistry
Alkanes, alkenes, alkynes
Functional groups and isomerism
Naming organic compounds
12. Water and Air
Composition of air
Water purification methods
Hard and soft water
13. Rates of Reaction
Factors affecting reaction rate
Collision theory
14. Chemistry Laboratory and Practical Work
Apparatus and their uses
Safety procedures
Inference tables
15. Environmental Chemistry
Greenhouse gases
Acid rain
Effects of chemical pollution
Most Repeated NECO Chemistry Questions (2025/2026)
Here are examples of NECO Chemistry questions that appear often:
Define atomic number and mass number.
State three periodic trends and explain each.
Differentiate between ionic and covalent bonds with examples.
Name and describe three methods of separating mixtures.
Write and balance the chemical equation for the reaction between sodium and water.
Define acid and base according to Arrhenius theory.
State Charles’ Law and give its mathematical expression.
Calculate the number of moles in 44g of CO₂. (Molar mass = 44g/mol)
What is electrolysis? Mention two practical applications.
Distinguish between exothermic and endothermic reactions with examples.
Draw the structural formula of but-2-ene.
List two greenhouse gases and explain their effects.
Explain the difference between hard water and soft water.
State two factors that affect the rate of chemical reactions.
Mention three safety rules observed in a chemistry laboratory.
👉 Click here to access NECO Chemistry past questions and complete answers (PDF)
Study Tips to Use NECO Chemistry Questions and Topics Effectively
Use the study hacks below to master NECO Chemistry:
✅ Create a Chemistry Study Plan
Study at least one topic daily. Use the 15 repeated topics as your guide.
✅ Practice Calculations and Equations
Don’t skip calculation-based topics like mole concept and gas laws.
✅ Use Flashcards and Summary Notes
Write key definitions, formulas, and reactions on flashcards.
✅ Solve Past Questions Regularly
Use real NECO past questions to simulate exam conditions.
✅ Revise Organic Chemistry with Diagrams
Practice drawing structures of organic compounds and naming them.
✅ Focus on Laboratory Practical
Learn salt preparation, tests for gases, and observation-based questions.
✅ Test Yourself Often
Create quizzes or ask a friend to challenge you with past questions.
👉 Click here to download NECO Chemistry theory and objective answers in PDF
❓FAQ – Most Repeated NECO Chemistry Topics, Questions and Answers
1. Are NECO Chemistry questions repeated every year?
Yes. NECO frequently repeats theory and objective questions with little or no change.
2. Can I pass Chemistry by studying only past questions?
You can pass if you understand the concepts and know how to apply them.
3. What are the most repeated Chemistry topics in NECO?
Mole concept, organic chemistry, periodic table, bonding, and acids & bases are top topics.
4. Is NECO Chemistry hard?
It can be tricky, but it’s easy if you understand basic principles and practice calculations.
5. Where can I get NECO Chemistry past questions and answers?
👉 Click the link above to download the full PDF of past questions and solutions.
6. Are the questions the same in NECO GCE and SSCE?
Yes. The same Chemistry syllabus and pattern apply to both exams.
7. How do I prepare for Chemistry practical?
Study common tests for ions and gases, read lab procedures, and memorize inference tables.
8. How many questions are in NECO Chemistry theory and objective?
Usually:
Objective = 50 multiple-choice questions
Theory = 4 to 6 long-answer questions
Practical = Separate paper (Experiment-based)
9. What kind of objective questions come in Chemistry?
Definitions, reactions, laws, symbols, calculations, and applications.
10. When is the best time to start studying for NECO Chemistry?
Start 3–4 months before the exam. Practice makes perfect.
✅ Conclusion
NECO Chemistry becomes easier when you focus on the most repeated topics and past questions. Follow this guide, master the key areas, solve questions with understanding, and prepare to pass with confidence.