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Ikiodiete George
- 3 Min Read
Neco Chemistry Exam (2025/2026): Full List Of Most Repeated Topics & Past Questions
The NECO Chemistry exam is one of the most challenging science subjects—but with the right focus, you can pass it easily. One of the smartest ways to prepare is to study the most repeated topics and frequently asked past questions.
This guide breaks down:
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Most repeated theory, objective, and practical topics
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Sample past questions (OBJ & Essay)
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Important definitions and chemical laws
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NECO Chemistry exam tips to score A1
NECO Chemistry Exam Format
| Paper | Type | Description |
|---|---|---|
| Paper I | Objective (OBJ) | 50 multiple-choice questions |
| Paper II | Theory/Essay | 6–7 structured questions (answer any 4) |
| Paper III | Practical/Alt. to Practical | Based on laboratory experiments, tests, and inference tables |
Most Repeated NECO Chemistry Topics
| Topic | Description |
|---|---|
| Atomic Structure & Periodic Table | Structure of atom, electron configuration, periodic trends |
| Chemical Bonding | Ionic, covalent, hydrogen bonding, metallic bonds |
| Mole Concept & Stoichiometry | Mole calculations, molar mass, empirical formula |
| Acids, Bases & Salts | Properties, reactions, titration, pH scale |
| Chemical Reactions | Types: combination, decomposition, displacement, combustion |
| Organic Chemistry | Hydrocarbons, alcohols, alkanes, alkenes, functional groups |
| Gas Laws | Boyle’s law, Charles’ law, Ideal gas law |
| Electrolysis | Electrolytes, electrochemical cells, Faraday’s laws |
| Water and Air | Properties of water, purification, atmospheric gases |
| Periodic Classification | Groups, periods, periodicity of elements |
| Thermochemistry | Enthalpy change, endothermic/exothermic reactions |
| Separation Techniques | Filtration, distillation, chromatography |
Sample NECO Chemistry Objective Questions (Repeated Often)
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Which of these is a noble gas?
A. Oxygen
B. Nitrogen
C. Helium
D. Hydrogen
✅ Answer: C -
Which process involves gain of electrons?
A. Oxidation
B. Reduction
C. Combustion
D. Neutralization
✅ Answer: B -
Which law relates pressure and volume of gases?
A. Charles’ Law
B. Boyle’s Law
C. Avogadro’s Law
D. Graham’s Law
✅ Answer: B
Sample NECO Chemistry Essay Questions (Frequently Repeated)
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Define mole and calculate the number of molecules in 11g of carbon dioxide (CO₂).
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Describe the laboratory preparation of oxygen and list its properties.
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Write chemical equations to show the reactions of acids with:
a) metals
b) bases
c) carbonates -
With examples, explain three types of chemical bonding.
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State and explain Boyle’s law, and solve a gas law calculation question.
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Compare and contrast alkanes and alkenes with examples.
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Describe the electrolysis of acidified water, showing the reactions at both electrodes.
Practical Chemistry (Paper III) – Common Specimens & Tasks
| Topic Area | Practical Task/Observation |
|---|---|
| Titration | Acid-base titration using phenolphthalein/methyl orange |
| Qualitative Analysis | Test for cations/anions using NaOH or HCl |
| Solubility | Heat solubility test of salts in water |
| Flame Test | Identify metal ions using colour of flame |
| Preparation of Salts | Mixing reagents to produce and crystallize a salt |
| Water Hardness | Comparison of lather formation, soap test |
Year-by-Year Topic Trends in NECO Chemistry
| Year | Most Repeated Topics |
|---|---|
| 2024 | Titration, chemical bonding, gas laws, electrolysis |
| 2023 | Organic chemistry, water treatment, mole concept |
| 2022 | Electrolysis, periodic table trends, acids & bases |
| 2021 | Separation techniques, oxidation/reduction, stoichiometry |
Key Chemistry Definitions You Must Know
| Term | Definition |
|---|---|
| Mole | The amount of substance containing the same number of entities as in 12g of C-12 |
| Ionization Energy | The energy required to remove one electron from a neutral atom |
| Isotopes | Atoms of the same element with different mass numbers |
| Electrolysis | The chemical decomposition of a substance using electric current |
| Empirical Formula | The simplest ratio of elements in a compound |
Tips to Pass NECO Chemistry With A1
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Practice titration calculations and ionic equations
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Focus on organic chemistry, bonding, and gas laws
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Memorize and practice chemical tests for salts and gases
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Study past NECO questions from at least the last 5 years
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Label diagrams neatly and avoid skipping calculations
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Use flashcards for formulas, laws, and element symbols
NECO Chemistry FAQs
Q: Does NECO repeat Chemistry questions?
Yes. Many theory and objective questions appear every 2–3 years.
Q: How can I improve in NECO Chemistry Practical?
Practice titration setups, salt tests, and know reagent colours. Use past practical papers for practice.
Q: Is organic chemistry compulsory in NECO?
Yes. It's often tested in both OBJ and theory sections. Focus on alkanes, alkenes, alcohols and their reactions.
Q: What’s the most difficult topic in NECO Chemistry?
Most students struggle with calculations and stoichiometry, but consistent practice solves that.
Final Thoughts
NECO Chemistry may seem tough, but with smart preparation, you can pass it with confidence. Focus your energy on mole concepts, bonding, titration, gas laws, and organic chemistry. Always review past questions and understand practical procedures.
“Chemistry is not magic—it’s logic and consistency. Master it step by step!”
