NECO 2025/2026 Chemistry Objective and Essay Questions and Answers

NECO 2025/2026 Chemistry Objective and Essay Questions and Answers

NECO 2025/2026 Chemistry Objective and Essay Questions and Answers

SECTION A: Objective Questions (1–50)

Instructions: Choose the correct option A–D that best answers each question.

1. The smallest particle of an element that takes part in a chemical reaction is called —
   A. molecule
   B. ion
   C. atom
   D. electron
   Answer: C

2. The nucleus of an atom contains —
   A. electrons only
   B. neutrons only
   C. protons and neutrons
   D. protons and electrons
   Answer: C

3. The relative atomic mass of an element is the average mass of its —
   A. protons
   B. isotopes
   C. neutrons
   D. atoms
   Answer: B

4. An element with atomic number 8 has —
   A. 4 electrons
   B. 6 electrons
   C. 8 electrons
   D. 16 electrons
   Answer: C

5. The electronic configuration of sodium (Na) is —
   A. 2:6
   B. 2:8
   C. 2:8:1
   D. 2:8:8
   Answer: C

6. Which of the following is a compound?
   A. Air
   B. Water
   C. Hydrogen
   D. Iron
   Answer: B

7. Which of the following is used to test for the presence of carbon dioxide?
   A. Blue litmus paper
   B. Lime water
   C. Red litmus paper
   D. Iodine
   Answer: B

8. Which of the following elements is a halogen?
   A. Neon
   B. Fluorine
   C. Potassium
   D. Calcium
   Answer: B

9. The modern periodic table is arranged in order of increasing —
   A. atomic mass
   B. atomic number
   C. mass number
   D. reactivity
   Answer: B

10. The type of bonding in sodium chloride is —
    A. covalent
    B. ionic
    C. metallic
    D. hydrogen
    Answer: B

11. Which of these is a physical change?
    A. Rusting of iron
    B. Boiling of water
    C. Burning of wood
    D. Souring of milk
    Answer: B

12. A solution that resists change in pH is called —
    A. base
    B. acid
    C. buffer
    D. salt
    Answer: C

13. Which gas is evolved when metals react with dilute acids?
    A. Oxygen
    B. Hydrogen
    C. Nitrogen
    D. Carbon dioxide
    Answer: B

14. The pH of a neutral solution is —
    A. 14
    B. 7
    C. 0
    D. 4
    Answer: B

15. The chemical formula of calcium carbonate is —
    A. CaCO₃
    B. CaCl₂
    C. CaSO₄
    D. Ca(OH)₂
    Answer: A

16. The component of air that supports combustion is —
    A. carbon dioxide
    B. nitrogen
    C. oxygen
    D. argon
    Answer: C

17. The gas that turns limewater milky is —
    A. oxygen
    B. hydrogen
    C. nitrogen
    D. carbon dioxide
    Answer: D

18. The laboratory preparation of hydrogen involves the reaction between zinc and —
    A. water
    B. hydrochloric acid
    C. nitric acid
    D. sodium hydroxide
    Answer: B

19. A catalyst —
    A. slows down chemical reactions
    B. increases the amount of products
    C. speeds up chemical reactions
    D. becomes part of the products
    Answer: C

20. Electrolysis is the —
    A. movement of electrons
    B. splitting of a compound using electricity
    C. purification of metals
    D. mixing of gases
    Answer: B

21. A substance that can donate protons is —
    A. acid
    B. base
    C. salt
    D. water
    Answer: A

22. The process of converting an unsaturated hydrocarbon to a saturated one is —
    A. cracking
    B. hydrogenation
    C. polymerization
    D. halogenation
    Answer: B

23. Which of the following is not an alkane?
    A. Methane
    B. Ethane
    C. Propene
    D. Butane
    Answer: C

24. The molecular formula of ethanol is —
    A. CH₄
    B. C₂H₆O
    C. C₂H₄O₂
    D. C₄H₁₀
    Answer: B

25. Which of these is not an allotrope of carbon?
    A. Graphite
    B. Diamond
    C. Charcoal
    D. Ammonia
    Answer: D

26. Hard water can be softened by —
    A. heating
    B. adding more salts
    C. filtering
    D. adding soap
    Answer: A

27. A salt formed from a strong acid and a weak base is —
    A. neutral
    B. acidic
    C. basic
    D. amphoteric
    Answer: B

28. Which of the following is used as fuel?
    A. Helium
    B. Hydrogen
    C. Nitrogen
    D. Oxygen
    Answer: B

29. When acid reacts with base, the product is —
    A. salt only
    B. water only
    C. salt and water
    D. base
    Answer: C

30. Which of the following is used as a drying agent?
    A. CaCl₂
    B. HCl
    C. NaCl
    D. NH₃
    Answer: A

31. The gas that bleaches litmus paper is —
    A. hydrogen
    B. oxygen
    C. ammonia
    D. chlorine
    Answer: D

32. Which of the following is not a pollutant?
    A. Carbon monoxide
    B. Nitrogen
    C. Lead
    D. Sulphur dioxide
    Answer: B

33. The process of obtaining pure crystals from a solution is —
    A. distillation
    B. evaporation
    C. filtration
    D. crystallization
    Answer: D

34. Which of these processes involves chemical change?
    A. Freezing
    B. Melting
    C. Burning
    D. Evaporating
    Answer: C

35. Which of the following is used to purify water?
    A. Sulphuric acid
    B. Sodium chloride
    C. Alum
    D. Potassium nitrate
    Answer: C

36. Which of the following is a base?
    A. HCl
    B. NaOH
    C. HNO₃
    D. CH₃COOH
    Answer: B

37. The number of protons in an element is called its —
    A. atomic mass
    B. mass number
    C. atomic number
    D. neutron number
    Answer: C

38. Which element has atomic number 1?
    A. Helium
    B. Hydrogen
    C. Oxygen
    D. Lithium
    Answer: B

39. Which of the following is not a method of separating mixtures?
    A. Distillation
    B. Filtration
    C. Electrolysis
    D. Chromatography
    Answer: C

40. The measure of randomness in a system is —
    A. enthalpy
    B. entropy
    C. energy
    D. temperature
    Answer: B

41. What is the molar volume of an ideal gas at STP?
    A. 22.4 dm³
    B. 20.0 dm³
    C. 1.0 dm³
    D. 11.2 dm³
    Answer: A

42. The general formula for alkanes is —
    A. CnH2n+1
    B. CnH2n
    C. CnH2n+2
    D. CnHn
    Answer: C

43. The reaction between ethene and hydrogen is an example of —
    A. cracking
    B. addition
    C. substitution
    D. combustion
    Answer: B

44. The laboratory apparatus used to measure temperature is —
    A. barometer
    B. thermometer
    C. voltmeter
    D. manometer
    Answer: B

45. The functional group in alcohols is —
    A. -OH
    B. -COOH
    C. -NH₂
    D. -CHO
    Answer: A

46. The major constituent of biogas is —
    A. methane
    B. carbon dioxide
    C. hydrogen
    D. ammonia
    Answer: A

47. The periodic table is divided into periods and —
    A. isotopes
    B. rows
    C. groups
    D. shells
    Answer: C

48. An example of a noble gas is —
    A. argon
    B. oxygen
    C. chlorine
    D. nitrogen
    Answer: A

49. Which acid is found in car batteries?
    A. Hydrochloric acid
    B. Nitric acid
    C. Sulphuric acid
    D. Ethanoic acid
    Answer: C

50. Which of the following is a greenhouse gas?
    A. Helium
    B. Carbon dioxide
    C. Neon
    D. Nitrogen
    Answer: B

NECO 2025/2026 Chemistry Objective and Essay Questions and Answers

SECTION B: Essay Questions

Answer any four (4) questions. All questions carry equal marks.

Question 1:
(a) Define the following:
(i) Atom
(ii) Isotope
(b) Give two examples of isotopes and state one use of isotopes.

Question 2:
(a) Define electrolysis.
(b) Explain the electrolysis of acidified water using labelled diagrams.
(c) State three uses of electrolysis.

Question 3:
(a) State two differences between metals and non-metals.
(b) Write short notes on any two of the following:
(i) Acid
(ii) Base
(iii) Salt

Question 4:
(a) What is a chemical equation?
(b) Balance the following equation:
__Fe + __Cl₂ → __FeCl₃
(c) Explain the law of conservation of mass.

Question 5:
(a) Describe the laboratory preparation of hydrogen gas.
(b) List two physical and two chemical properties of hydrogen.

Question 6:
(a) Define organic chemistry.
(b) Give the IUPAC names and molecular formulae of the first four alkanes.
(c) State one physical and one chemical property of alkanes.