NECO Chemistry Examination 2025: Questions and Answers

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NECO Chemistry Examination 2025: Full Breakdown and Preparation Guide with questions and answers

But before then quickly go through the breakdown of 2025 NECO exam below:

Get the full breakdown of the ongoing NECO Chemistry Examination 2025, including the timetable, exam structure, key syllabus topics, and preparation tips. Perfect guide for school candidates aiming for success.

Introduction

The National Examinations Council (NECO) Chemistry exam is one of the core science subjects for senior secondary school candidates. The exam tests a student’s understanding of theoretical principles and practical skills in chemistry. The ongoing 2025 NECO Chemistry examination is structured to assess students in three major components: Practical, Objective, and Essay.

This guide provides a complete breakdown of the NECO Chemistry exam, including the timetable, structure, key topics, and preparation strategies.

NECO Chemistry 2025 Timetable

As stated in the official NECO timetable for school candidates:

  • Paper I – Practical
    • Date: Monday, June 30, 2025
    • Time: 10:00 am – 12:00 pm
    • Duration: 2 hours
  • Papers III & II – Objective and Essay
    • Date: Wednesday, July 9, 2025
    • Time: 10:00 am – 1:00 pm
    • Duration: 3 hours

Examination Structure and Marking Scheme

The Chemistry examination is divided into three main papers:

Paper I – Practical (50 Marks, 2 Hours)

This paper tests students’ ability to carry out laboratory experiments, make accurate observations, and report results. It includes:

  • Volumetric analysis (titration)
  • Qualitative analysis (test for ions)
  • Simple physical chemistry experiments

Students are expected to identify unknown substances, observe chemical changes, record data, and interpret results.

Paper II – Essay (100 Marks, 2 Hours)

This paper consists of two sections:

  • Section A: Ten short structured questions (compulsory), covering a wide range of topics (25 marks)
  • Section B: Four essay questions out of which candidates must answer three (75 marks)

The questions in this section demand detailed explanations, calculations, definitions, and chemical equations.

Paper III – Objective (50 Marks, 1 Hour)

This paper contains 50 multiple-choice questions covering all areas of the syllabus, including:

  • Basic concepts of chemistry
  • Atomic structure
  • Chemical bonding
  • Periodic table
  • Organic chemistry
  • Environmental chemistry
  • Chemical reactions and stoichiometry

Key Areas to Study

The NECO Chemistry syllabus includes both theoretical and practical aspects. Below are essential topics to cover:

Theoretical Topics:

  • Atomic structure and periodicity
  • Chemical bonding and structure
  • States of matter and gas laws
  • Acids, bases, salts, and pH
  • Thermochemistry and chemical equilibrium
  • Electrolysis and electrochemical cells
  • Organic chemistry (hydrocarbons, alcohols, carboxylic acids)
  • Environmental chemistry (water and air pollution)

Practical Topics:

  • Titration (acid-base and redox)
  • Test for anions and cations
  • Simple experiments on rates of reaction
  • Identification of gases and unknown substances

Required Materials for Practical Paper

To perform well in the practical paper, students should be familiar with the following tools and chemicals:

  • Burette, pipette, and conical flask
  • Beakers, test tubes, and test tube rack
  • White tiles and filter paper
  • Indicators such as phenolphthalein and methyl orange
  • Common laboratory reagents (acids, bases, salts)
  • Distilled water and chemical wash bottles

Preparation Tips

  1. Practice Past Questions
    Solve both essay and objective past questions to understand the question pattern and common topics.
  2. Revise Key Topics Regularly
    Focus on high-weight areas such as titration, electrolysis, chemical bonding, and organic chemistry.
  3. Improve Laboratory Skills
    Get hands-on practice with volumetric and qualitative analysis. Know how to handle chemicals safely and accurately.
  4. Memorize Key Equations and Definitions
    Learn important chemical equations, definitions, and scientific laws for quick recall in the exam.
  5. Simulate Exam Conditions
    Time yourself while solving full past papers to build speed and confidence.
  6. Ask Questions and Clarify Doubts
    Discuss difficult topics with classmates or teachers before the exam.

READ ALSO

Few sample NECO Chemistry past questions and answers covering Objective, Essay, and Practical formats to help with your preparation:

A. Objective Questions (Multiple Choice)

Choose the correct option for each question.

  1. The number of protons in the nucleus of an atom is known as its:
    A. mass number
    B. nucleon number
    C. atomic number
    D. neutron number
    Answer: C. atomic number
  2. Which of the following gases is used in the manufacture of ammonia by the Haber process?
    A. Oxygen and hydrogen
    B. Nitrogen and hydrogen
    C. Nitrogen and oxygen
    D. Hydrogen and chlorine
    Answer: B. Nitrogen and hydrogen
  3. What is the oxidation number of sulfur in H₂SO₄?
    A. +2
    B. +4
    C. +6
    D. +8
    Answer: C. +6
  4. Which of the following is a saturated hydrocarbon?
    A. Ethene
    B. Ethyne
    C. Butane
    D. Benzene
    Answer: C. Butane
  5. Which of the following processes will result in a chemical change?
    A. Melting of ice
    B. Dissolving salt in water
    C. Burning of wood
    D. Breaking glass
    Answer: C. Burning of wood

B. Essay Questions (Theory)

  1. (a) Define an acid and a base according to the Bronsted-Lowry theory.
    (b) Write the balanced chemical equation for the reaction between:
    • Sodium hydroxide and hydrochloric acid
    • Ammonia and water
      Answer:
      (a) An acid is a substance that donates protons (H⁺ ions), and a base is a substance that accepts protons.
      (b)
      NaOH + HCl → NaCl + H₂O
      NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
  2. (a) State four differences between a chemical change and a physical change.
    (b) List three chemical properties of matter.
    Answer:
    (a)
    • Chemical change produces a new substance; physical change does not.
    • Chemical change is usually irreversible; physical change is reversible.
    • Chemical change involves energy release or absorption; physical change does not involve much energy change.
    • Chemical change changes the composition of the substance; physical change does not.
      (b)
    • Reactivity with water
    • Flammability
    • pH or acidity/basicity

C. Practical (Qualitative and Quantitative)

Titration Problem:
25.0 cm³ of NaOH solution was pipetted into a conical flask and titrated against 0.10 mol/dm³ HCl. The average volume of acid used was 20.0 cm³. Calculate the concentration of NaOH in mol/dm³.

Answer:
Balanced equation:
NaOH + HCl → NaCl + H₂O

Using:
C₁V₁ = C₂V₂
C₁ × 25 = 0.10 × 20
C₁ = (0.10 × 20) / 25 = 0.08 mol/dm³

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Conclusion

The NECO Chemistry exam is a major requirement for science students aspiring to study courses like Medicine, Pharmacy, Engineering, and Pure Sciences. Success in this subject requires a balance of theoretical knowledge and practical skill. With proper preparation, consistent practice, and attention to detail, students can perform excellently in the NECO Chemistry 2025 examination.

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