Past Questions and Answers

2026 NECO Chemistry Objective and Essay Questions and Answers

Etima Harrison July 8, 2026

2,194 10 minutes read

CHEMISTRY

PAPER I – OBJECTIVE TEST (PART 1)

Time Allowed: 1 Hour 30 Minutes

Note: This is an original practice paper designed to reflect the current NECO Chemistry syllabus and examination style. It is not an official or leaked 2026 examination paper. The questions cover core syllabus areas such as atomic structure, stoichiometry, periodic chemistry, acids and bases, organic chemistry, and electrochemistry.

INSTRUCTIONS TO CANDIDATES

Answer Questions 1–30.
Each question is followed by four options (A–D).
Choose the most appropriate answer.
Each question carries 1 mark.

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QUESTIONS 1–60

1. The smallest particle of an element that retains its chemical properties is the
A. Molecule
B. Ion
C. Atom
D. Electron

Answer: C

2. The atomic number of an element is equal to the number of
A. Neutrons only
B. Electrons only
C. Protons
D. Nucleons

Answer: C

3. Isotopes of an element have the same
A. Mass number
B. Number of neutrons
C. Atomic number
D. Relative molecular mass

Answer: C

4. Which particle has no electrical charge?
A. Electron
B. Proton
C. Neutron
D. Positron

Answer: C

5. The maximum number of electrons in the second shell is
A. 2
B. 8
C. 18
D. 32

Answer: B

6. Sodium belongs to Group
A. I
B. II
C. VII
D. VIII

Answer: A

7. Chlorine belongs to
A. Noble gases
B. Halogens
C. Alkali metals
D. Transition metals

Answer: B

8. The most reactive non-metal is
A. Oxygen
B. Chlorine
C. Fluorine
D. Nitrogen

Answer: C

9. Electrovalent bonding involves
A. Sharing of electrons
B. Transfer of electrons
C. Sharing of protons
D. Transfer of neutrons

Answer: B

10. Methane (CH₄) contains
A. Ionic bonds only
B. Metallic bonds
C. Covalent bonds
D. Hydrogen bonds

Answer: C

11. Which compound is ionic?
A. H₂O
B. CO₂
C. NaCl
D. NH₃

Answer: C

12. Diamond is a giant
A. Ionic crystal
B. Metallic lattice
C. Covalent structure
D. Molecular crystal

Answer: C

2026 NECO Chemistry Objective and Essay Questions and Answers

13. One mole contains
A. 6.02 × 10²³ particles
B. 6.02 × 10²² particles
C. 3.01 × 10²³ particles
D. 1.00 × 10²³ particles

Answer: A

14. The relative molecular mass of H₂SO₄ is
A. 96
B. 98
C. 100
D. 102

Answer: B

15. Which law states that matter is neither created nor destroyed during a chemical reaction?
A. Boyle’s law
B. Charles’ law
C. Law of Conservation of Mass
D. Avogadro’s law

Answer: C

16. Diffusion is fastest in
A. Solids
B. Liquids
C. Gases
D. Plasma only

Answer: C

17. Increasing temperature generally causes gas molecules to
A. Move more slowly
B. Stop moving
C. Move faster
D. Become liquids

Answer: C

Acids, Bases and Salts

18. Which of the following is an acid?
A. NaOH
B. NH₄OH
C. HCl
D. KOH

Answer: C

19. Blue litmus turns red in
A. Alkalis
B. Acids
C. Salts
D. Water

Answer: B

20. The pH of a neutral solution is
A. 1
B. 5
C. 7
D. 14

Answer: C

21. Neutralization produces
A. Acid only
B. Alkali only
C. Salt and water
D. Hydrogen only

Answer: C

Organic Chemistry

22. The simplest hydrocarbon is
A. Ethane
B. Methane
C. Propane
D. Butane

Answer: B

23. Ethene belongs to the
A. Alkanes
B. Alkenes
C. Alkynes
D. Alcohols

Answer: B

24. Fermentation of sugar produces
A. Ethanol
B. Methane
C. Benzene
D. Ethanoic acid

Answer: A

2026 NECO Chemistry Objective and Essay Questions and Answers

25. Oxidation involves
A. Gain of electrons
B. Loss of electrons
C. Gain of neutrons
D. Loss of protons

Answer: B

26. Reduction is
A. Gain of electrons
B. Gain of oxygen
C. Loss of hydrogen
D. Increase in oxidation number

Answer: A

27. Electrolysis requires
A. Heat only
B. Electric current
C. Sunlight only
D. Pressure

Answer: B

28. The major constituent of natural gas is
A. Propane
B. Butane
C. Methane
D. Ethene

Answer: C

29. Acid rain is mainly caused by
A. Carbon dioxide and nitrogen
B. Sulfur dioxide and nitrogen oxides
C. Oxygen and hydrogen
D. Chlorine gas

Answer: B

30. A catalyst
A. Is consumed during a reaction
B. Slows every reaction
C. Increases the rate of reaction without being permanently changed
D. Changes the products formed

Answer: C

31. Boyle’s law states that for a fixed mass of gas at constant temperature, the pressure is
A. Directly proportional to the volume
B. Inversely proportional to the volume
C. Equal to the volume
D. Independent of the volume

Answer: B

32. Charles’ law states that the volume of a fixed mass of gas is directly proportional to its absolute temperature at constant
A. Mass
B. Pressure
C. Density
D. Humidity

Answer: B

33. Which instrument is commonly used to measure atmospheric pressure?
A. Hydrometer
B. Thermometer
C. Barometer
D. Hygrometer

Answer: C

2026 NECO Chemistry Objective and Essay Questions and Answers

34. Which of the following factors generally increases the rate of a chemical reaction?
A. Lower temperature
B. Smaller surface area
C. Presence of a catalyst
D. Lower concentration of reactants

Answer: C

35. A catalyst functions by
A. Increasing the activation energy
B. Decreasing the activation energy
C. Being completely used up during the reaction
D. Changing the products formed

Answer: B

36. An exothermic reaction
A. Absorbs heat from the surroundings
B. Releases heat to the surroundings
C. Occurs only in gases
D. Cannot be reversed

Answer: B

37. Which process is endothermic?
A. Freezing of water
B. Condensation
C. Melting of ice
D. Neutralization

Answer: C

38. Chemical equilibrium is established when
A. Reactants are completely consumed
B. Forward and reverse reactions occur at equal rates
C. The reaction stops completely
D. Products are removed continuously

Answer: B

39. Increasing the concentration of reactants generally shifts the equilibrium toward
A. Reactants
B. Products
C. Neither side
D. The catalyst

Answer: B

40. The solubility of most solid substances in water generally
A. Decreases with increasing temperature
B. Increases with increasing temperature
C. Remains constant
D. Becomes zero

Answer: B

2026 NECO Chemistry Objective and Essay Questions and Answers

41. Blue litmus paper turns red in the presence of
A. Alkalis
B. Acids
C. Salts
D. Neutral solutions

Answer: B

42. Which reagent is commonly used to test for chloride ions?
A. Sodium hydroxide solution
B. Silver nitrate solution
C. Dilute hydrochloric acid
D. Bromine water

Answer: B

43. A white precipitate with silver nitrate indicates the possible presence of
A. Sulfate ions
B. Chloride ions
C. Carbonate ions
D. Nitrate ions

Answer: B

44. Carbon dioxide gas turns ______ milky.
A. Limewater
B. Bromine water
C. Distilled water
D. Ethanol

Answer: A

45. During electrolysis, oxidation occurs at the
A. Cathode
B. Anode
C. Salt bridge
D. Electrolyte only

Answer: B

46. Reduction takes place at the
A. Anode
B. Cathode
C. Positive terminal only
D. Electrolyte

Answer: B

47. The extraction of aluminium is carried out mainly by
A. Distillation
B. Electrolysis
C. Filtration
D. Sublimation

Answer: B

48. Rusting of iron requires
A. Nitrogen only
B. Oxygen and water
C. Carbon dioxide only
D. Hydrogen only

Answer: B

49. The functional group present in alcohols is
A. –COOH
B. –OH
C. –CHO
D. –NH₂

Answer: B

50. Ethanoic acid belongs to the family of
A. Alcohols
B. Esters
C. Carboxylic acids
D. Ketones

Answer: C

51. Unsaturated hydrocarbons contain at least one
A. Ionic bond
B. Double or triple carbon-carbon bond
C. Metallic bond
D. Hydrogen bond

Answer: B

52. The addition of hydrogen to an unsaturated compound is known as
A. Polymerization
B. Hydrogenation
C. Fermentation
D. Cracking

Answer: B

53. Which gas contributes most to the greenhouse effect?
A. Hydrogen
B. Carbon dioxide
C. Nitrogen
D. Helium

Answer: B

54. Ozone in the stratosphere is important because it
A. Produces rainfall
B. Absorbs harmful ultraviolet radiation
C. Causes acid rain
D. Increases air pollution

Answer: B

55. Water hardness caused by calcium hydrogen carbonate is known as
A. Permanent hardness
B. Temporary hardness
C. Saline hardness
D. Industrial hardness

Answer: B

56. Which method removes temporary hardness from water?
A. Boiling
B. Filtration
C. Distillation
D. Sedimentation

Answer: A

57. The relative molecular mass (Mr) of CO₂ is
A. 40
B. 42
C. 44
D. 46

Answer: C

58. One mole of oxygen molecules (O₂) contains
A. $6.02 \times 10^{23}$ molecules
B. $3.01 \times 10^{23}$ molecules
C. $1.00 \times 10^{23}$ molecules
D. $12.04 \times 10^{23}$ molecules

Answer: A

59. The oxidation number of oxygen in most compounds is
A. +2
B. –2
C. +1
D. 0

Answer: B

60. Which of the following is an example of a chemical change?
A. Melting of ice
B. Dissolving sugar in water
C. Burning of magnesium ribbon
D. Breaking a glass bottle

Answer: C

CHEMISTRY

PAPER II – ESSAY (PROPOSED PRACTICE PAPER)

Time Allowed: 2 Hours 30 Minutes
Maximum Marks: 100

Note: This is an original practice paper designed to reflect the NECO Chemistry syllabus and examination style. It is intended for revision and is not an official or leaked 2026 examination paper.

INSTRUCTIONS TO CANDIDATES

Answer Five (5) questions only.
Question 1 is compulsory.
All questions carry 20 marks.
Where necessary, write balanced chemical equations.
Show all calculations clearly.
Credit will be given for correct chemical symbols, units, and logical presentation.

QUESTION 1 (COMPULSORY)

(a) Define the following:

i. Atom

ii. Molecule

iii. Mole

iv. Ion

(b) State the differences between:

i. Physical change and Chemical change

ii. Element and Compound

(c) State four physical properties and four chemical properties of matter.

MODEL ANSWER

(a)

Atom
The smallest particle of an element that retains its chemical properties.

Molecule
The smallest particle of a substance capable of independent existence and consisting of two or more atoms chemically combined.

Mole
The amount of substance containing 6.02 × 10²³ particles (Avogadro’s constant).

Ion
An atom or group of atoms carrying a positive or negative electrical charge due to the loss or gain of electrons.

(b)

Physical Change

No new substance is formed.
Usually reversible.
Only physical properties change.

Chemical Change

New substances are formed.
Usually irreversible.
Chemical composition changes.

Element

A pure substance made up of only one type of atom.

Compound

A substance formed when two or more elements combine chemically in fixed proportions.

(c)

Physical Properties

Density
Melting point
Boiling point
Colour

Chemical Properties

Combustibility
Reactivity with acids
Oxidation
Corrosion

2026 NECO Chemistry Objective and Essay Questions and Answers

QUESTION 2

(a) Explain the Periodic Table.

(b) State five characteristics of Group I (Alkali Metals).

(c) State five characteristics of Group VII (Halogens).

MODEL ANSWER

Periodic Table

The Periodic Table is an arrangement of elements in order of increasing atomic number, showing recurring patterns in their chemical and physical properties.

Characteristics of Group I

One valence electron.
Very reactive metals.
Form positive ions (+1).
React vigorously with water.
Soft and have relatively low melting points.

Characteristics of Group VII

Seven valence electrons.
Highly reactive non-metals.
Form negative ions (–1).
Exist as diatomic molecules.
React with metals to form salts.

QUESTION 3

(a) State Boyle’s Law.

(b) State Charles’ Law.

(c) A gas occupies 240 cm³ at 300 K. Calculate its volume at 450 K if the pressure remains constant.

MODEL ANSWER

Boyle’s Law

For a fixed mass of gas at constant temperature, the pressure is inversely proportional to its volume.

Charles’ Law

For a fixed mass of gas at constant pressure, the volume is directly proportional to its absolute temperature.

Calculation

Given:

V₁ = 240 cm³
T₁ = 300 K
T₂ = 450 K

Using Charles’ Law:

$V1T1=V2T2\frac{V_1}{T_1}=\frac{V_2}{T_2}$ $V2=240×450300V_2=\frac{240\times450}{300}$ $cm3V_2=360\ \text{cm}^3$

Answer: 360 cm³

QUESTION 4

(a) Explain Electrolysis.

(b) Differentiate between:

i. Electrolyte

ii. Electrode

iii. Electrolytic Cell

(c) State four applications of electrolysis.

MODEL ANSWER

Electrolysis

Electrolysis is the chemical decomposition of an electrolyte by passing an electric current through its molten or aqueous solution.

Differences

Electrolyte
A substance that conducts electricity when molten or dissolved in water because it contains mobile ions.

Electrode
A conductor through which electric current enters or leaves the electrolyte.

Electrolytic Cell
The apparatus in which electrolysis takes place.

Applications

Electroplating.
Purification of copper.
Extraction of aluminium.
Manufacture of chlorine and sodium hydroxide.

QUESTION 5

(a) Explain the following terms:

i. Acid

ii. Base

iii. Alkali

iv. Salt

(b) Describe three laboratory methods of preparing salts.

MODEL ANSWER

Definitions

Acid
A substance that produces hydrogen ions (H⁺) in aqueous solution.

Base
A substance that reacts with an acid to form salt and water.

Alkali
A soluble base that produces hydroxide ions (OH⁻) in water.

Salt
An ionic compound formed when the hydrogen ion of an acid is replaced by a metal or ammonium ion.

Preparation of Salts

1. Neutralization
Acid + Alkali → Salt + Water

Example:
HCl + NaOH → NaCl + H₂O

2. Reaction of Acid with Metal

Zn + H₂SO₄ → ZnSO₄ + H₂

3. Reaction of Acid with Carbonate

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

QUESTION 6

(a) Explain the following:

i. Hydrocarbons

ii. Homologous Series

iii. Functional Group

(b) Differentiate between Alkanes and Alkenes.

(c) State three uses each of Ethanol and Ethanoic Acid.

2026 NECO Chemistry Objective and Essay Questions and Answers

MODEL ANSWER

Definitions

Hydrocarbons
Compounds containing only carbon and hydrogen atoms.

Homologous Series
A family of organic compounds with the same functional group and general formula, where successive members differ by a –CH₂– unit.

Functional Group
The atom or group of atoms responsible for the characteristic chemical reactions of an organic compound.

Differences

Alkanes	Alkenes
Saturated hydrocarbons	Unsaturated hydrocarbons
Only single C–C bonds	At least one C=C double bond
General formula: CₙH₂ₙ₊₂	General formula: CₙH₂ₙ

Uses of Ethanol

Solvent in laboratories and industries.
Fuel or fuel additive (bioethanol).
Ingredient in pharmaceuticals and sanitizers.

Uses of Ethanoic Acid

Manufacture of vinegar.
Food preservation.
Production of chemicals such as esters and plastics.

QUESTION 7

(a) Explain corrosion.

(b) State five methods of preventing rusting.

(c) Explain the effects of environmental pollution caused by chemical substances.

MODEL ANSWER

Corrosion

Corrosion is the gradual deterioration of metals due to chemical or electrochemical reactions with their environment. Rusting is the corrosion of iron in the presence of oxygen and moisture.