2023 NECO Chemistry (OBJ, Theory & Essay) Answers [24th July]

Free Live 2023 NECO June/July Chemistry (CHEM) OBJ & Essay Questions and Answers!

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NECO 2023 Chemistry Questions (Video)

Second educational chemistry questions






(i) KAl(SO₄)₂. 12H₂O
(ii) Na₂SO₄

Number of moles of sodium reacted = reacting mass/molar mass
= 3.6/23
= 0.1565moles
Number of moles of oxygen reacted = (1/4) x Number of sodium
= 1/4 x (3.6/23)
= 0.03913
Reacting mass of oxygen = Number of moles x molar mass
= 0.03913 x (16×2)
= 1.252grams

Air in gaseous form is first passed through caustic soda to remove CO₂. It is compressed and cooled until ut becomes a liquid at -200°C. It is then led to a fractionating column. On distillation, Nitrogen which has a lowest boiling point of -196°C is evolved first leaving behind Oxygen in liquid form. Further heating converts the liquid to a gas at -183°C.

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(i) It is used for combustion
(ii) It is used for artificial respiration

This is because room temperature is warmer

(i) Methyl orange
(ii) Phenolphthalein

An ion is an atom or molecule which has a net electric charge due to the loss or gain of one or more electrons.

HCl gas doesn’t contain ions

(i) Noble gases: Neon, Helium
(ii) Halogens: Iodine, Fluorine
(iii) Alkaline earth metals: Calcium, Magnesium

Halogens attain stable octet configuration by accepting an electron from donors Group I elements.

A sol is a colloid where solid particles are dispersed in liquid medium.


(i) Acid-base titrations are used to determine the percentage purity of a substance
(ii) Acid-base titrations are important to determine the number of water molecules in a hydrate.


(i) High melting and boiling points
(ii) Exist mainly as solids at room temperature

(i) Ammonia, NH₃
(ii) Hydrogen chloride gas, HCl

(i) Potassium hexacyanoferrate(II)
(ii) It is a complex salt

(i) Wrought iron
(ii) Cast iron

2H₂ + O₂ →2H₂O
2 : 1 : 2
Reacting volumes;
40cm³ : 20cm³ : 40cm³
Residual volumes;
(50 – 40) (20 – 20)
= 10cm³ = 0cm³ = 40cm³
Total residual volume = 10 + 40
= 50cm³

(ii) Hydrofluorocarbon

I – C₂H₂OH + H₂SO₄ —>C₂H₅HSO₄ + H₂O
II – C₂H₅HSO₄ —> C₂H₄ +H₂SO₄

(i) They incompletely filled d-orbitals
(ii) They exhibit variable oxidation state

(i) It is used in making aeroplane parts due to its tensile strength
(ii) It is used in making window frames because it cannot be easily oxidised

A white precipitate is formed with evolution of brown gas

(i) Hydrogen bond
(ii) Covalent bond

(i) Oxidation
(ii) Electrolysis


H₂SO₄ + 2NaOH —> Na₂SO₄ +2H₂O
CaVa/CbVb = Na/NB
Va = CbVbna/Can
Va = 0.1×25×1/0.5×2
Va = 2.5cm³

Rate of a chemical reaction is defined as the number of moles of reactant converted or product formed per unit time.

Mass of CaCO3 = 3g
Molar mass of CaCO3= 100g/mol
No. of moles = 3/100 = 0.03
Time = 2×60 = 120s
Rate of reaction = No. of moles/Time
= 0.03/120 = 2.5 × 10-⁴

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(i) They are more resistant to corrosion
(ii) They are more durable
(iii) They have lower melting point

2Pb(NO₃)₂ —> 2PbO + 4NO₂ +O₂

I =Hard water=
(i)It has better taste than soft water
(ii) It can be supplied in lead pipes as it does not dissolve lead

II =Soft water=
(i) It does not deposit scale in boilers and fur in kettles
(ii) It does not waste soap

I – CO
II – SO₂

I – Hardness
II – Lustre appearance
III – Conductivity
IV – Ability to absorb

4.3/2.12 = 142+18x/142
2.12(142+18x)/2.12 = 4.3*142/2.12
142+18x = 288
18x = 288-142
x = 146/18
x = 8


Are you getting ready for the NECO Chemistry exam? You’ve come to the right place! This comprehensive guide will offer valuable information and insights into the NECO Chemistry Objective & Essay 2023 questions and answers. Whether you’re a student, teacher, or parent, this article will be your ultimate resource to achieve success in the upcoming examination.

Understanding the NECO Chemistry Exam

The NECO Chemistry exam holds significant importance for Senior Secondary School students in Nigeria, as it serves as a vital assessment of their knowledge and comprehension of various chemistry concepts and principles. This examination is divided into two sections: the Objective section and the Essay section. Let’s explore each section to gain a comprehensive understanding.

Best way to Prepare for the NECO Chemistry Exam

Preparing for the NECO Chemistry exam requires a systematic and focused approach. Here are some effective strategies to help you excel in the exam:

1. Understand the Syllabus: Start by thoroughly reviewing the NECO Chemistry syllabus. Understand the topics and sub-topics that are covered in the exam. This will give you a clear roadmap of what to study.

2. Create a Study Schedule: Plan your study time effectively by creating a study schedule. Allocate specific time slots for each topic, giving more time to areas that you find challenging.

3. Study Regularly: Consistency is key to success. Study regularly and avoid last-minute cramming. Understanding and retaining the concepts is more effective than rote memorization.

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4. Use Quality Study Resources: Gather quality study materials, including textbooks, reference books, past question papers, and online resources. Utilize these resources to enhance your understanding of the subject.

5. Practice with Past Papers: Solve previous years’ question papers to get familiar with the exam pattern and types of questions asked. It will also help you manage your time during the actual exam.

6. Seek Help and Clarifications: If you encounter difficulties in certain topics, don’t hesitate to seek help from teachers, peers, or online platforms. Clarifying your doubts will strengthen your knowledge.

7. Form Study Groups: Consider forming study groups with classmates. Collaborative learning can be beneficial as you can discuss and share ideas and concepts.

8. Take Mock Tests: Attempt mock tests or practice exams under exam-like conditions. It will help you gauge your preparation level and identify areas that need improvement.

9. Focus on Concepts and Applications: Instead of memorizing formulas and facts, focus on understanding the underlying concepts and their applications. This approach will enable you to tackle different question formats.

10. Stay Healthy and Manage Stress: Take care of your physical and mental health during the preparation phase. Get enough rest, eat well, and manage stress to maintain focus and concentration.


In conclusion, preparing for the NECO Chemistry exam requires dedication, organization, and a well-planned study approach. Understanding the syllabus, creating a study schedule, and using quality study resources are crucial steps to success. Regular practice with past papers and mock tests helps familiarize oneself with the exam pattern and boosts confidence. Seeking help and clarifying doubts, along with collaborative learning, further enhances preparation. Emphasizing conceptual understanding over memorization and managing physical and mental well-being contribute to optimal performance. By adopting these effective strategies, students can confidently tackle the NECO Chemistry exam and achieve their academic goals. Best wishes for a successful examination!

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