FREE WAEC ANSWERS 2026

Section A: 1. C (Melting of ice) 2. B (Mole) 3. A (6.02 × 10²³) 4. C (Air) 5. C (Fractional distillation) 6. C (Donates protons) 7. B (Red) 8. (Correct option should be a non-metal oxide like CO₂ — likely missing, but closest expected: acidic oxide = CO₂) 9. B (Hydrogen) 10. B (NaOH) 11. C (3) 12. C (Iron) 13. B (Sublimation) 14. C (Helium) 15. B (Na₂CO₃·10H₂O) 16. C (Nitrogen oxide) 17. C (Increases reaction rate) 18. C (Sulphuric acid) 19. C (Carbon monoxide) 20. D (Oxygen and water) 21. C (Ethene) 22. A (CₙH₂ₙ₊₂) 23. C (NH₃) 24. B (7) 25. C (Aluminium) 26. A (Bronze) 27. B (Oxidation occurs) 28. C (NaCl) 29. D (Helium) 30. B (NH₃) 31. B (Protons) 32. A (Limewater) 33. B (Temporary hardness) 34. A (Na₂O) 35. C (Bauxite) 36. C (H₂O) 37. B (Iron) 38. C (Carbon dioxide) 39. C (Sodium chloride) 40. C (Sodium) 41. C (Quicklime) 42. B (-OH) 43. D (All of the above) 44. C (CH₃COOH) 45. D (Methane) 46. C (Fluorine) 47. B (Neutralization) 48. C (HCl) 49. A (Sodium carbonate) 50. B (NO₂)

*OYO STATE MOCK CHEMISTRY THEORY ANSWER* *SECTION B* 1(a) (i) An atom is the smallest particle of an element that can take part in a chemical reaction and retains the properties of that element. (ii) Oxidation is the loss of electrons or addition of oxygen or removal of hydrogen. (iii) Reduction is the gain of electrons or removal of oxygen or addition of hydrogen. 1(b) Oxidizing and Reducing Agents (General answer since reaction is not clearly visible) Oxidizing agent: Substance that accepts electrons and gets reduced. Reducing agent: Substance that donates electrons and gets oxidized. 1(c) i. Rusting of iron ii. Combustion of fuels (burning) 1(d) An alloy is a mixture of two or more metals or a metal and a non-metal to improve properties. 1(e) Constituents of: 1(f) Brass → Copper + Zinc 1(g) Bronze → Copper + Tin 1(h) Two Advantages of Alloys Over Pure Metals Stronger and harder More resistant to corrosion

4(a) Redox Terms (i) Oxidation: Addition of oxygen or removal of hydrogen (or loss of electrons). (ii) Reduction: Removal of oxygen or addition of hydrogen (or gain of electrons). ⸻ 4(b) Oxidizing and Reducing Agents (Since the reaction is not clearly shown, use the general rule below in exams) • Oxidizing agent: Substance that gains electrons (is reduced) • Reducing agent: Substance that loses electrons (is oxidized) ⸻ 4(c) Applications of Redox Reactions • In batteries (production of electricity) • In respiration (energy release in the body) ⸻ 4(d) Alloy An alloy is a mixture of two or more metals (or a metal and a non-metal). ⸻ 4(e) Constituents • Brass: Copper + Zinc • Bronze: Copper + Tin ⸻ 4(f) Advantages of alloys over pure metals • Stronger than pure metals • More resistant to corrosion ⸻ 5(a) Functional group: An atom or group of atoms responsible for the chemical properties of an organic compound. ⸻ Functional groups in the given compound (CH₃COOCH₃) • Ester group (–COO–) ⸻ 5(b) Organic Compound Q From the structure (looks like CH₄): (i) Name of compound Q: Methane ⸻ (ii) Complete combustion equation: CH_4 + 2O_2 → CO_2 + 2H_2O ⸻ (iii) Reaction with chlorine: • Substitution reaction ⸻ (iv) Alkene isomer: Methane has no isomer, so likely intended compound is ethane (C₂H₆) Alkene isomer: Ethene (C₂H₄) Structure: CH₂ = CH₂ ⸻ 6(a) Organic Analysis Observations Interpretation: • A and B decolourize bromine: → They are unsaturated (contain double bond) • Only B reacts with ammoniacal silver nitrate: → B is a terminal alkyne • D reacts with sodium carbonate to produce CO₂: → D is a carboxylic acid • C + D + conc. H₂SO₄ gives fruity smell: → Esterification occurred → C is an alcohol 6(b) (i) Family of organic compounds • A: Alkene • B: Alkyne • C: Alcohol • D: Carboxylic acid ⸻ (ii) Why A and B reacted with bromine in tetrachloromethane They contain unsaturated bonds (C=C or C≡C) which undergo addition reaction, causing decolourization of bromine. ⸻ (iii) Why B gave a white precipitate with ammoniacal silver trioxonitrate (V) Because B is a terminal alkyne, which reacts with ammoniacal silver nitrate to form a white precipitate of silver alkynide. ⸻ (iv) Name of reaction between C and D Esterification reaction ⸻ (v) Two roles of concentrated tetraoxosulphate (VI) acid (H₂SO₄) • Acts as a catalyst • Acts as a dehydrating agent (removes water formed) ⸻ 6(d) (i) Production of biogas Biogas is produced by anaerobic decomposition of organic waste (e.g. animal dung, plant materials) in a biogas digester: • Organic waste is mixed with water • Placed in an airtight container (absence of oxygen) • Bacteria break it down to produce gas (mainly methane) • Gas is collected and stored for use ⸻ (ii) Two uses of biogas • Used as fuel for cooking • Used for generating electricity

Section A: 1. C (Melting of ice) 2. B (Mole) 3. A (6.02 × 10²³) 4. C (Air) 5. C (Fractional distillation) 6. C (Donates protons) 7. B (Red) 8. (Correct option should be a non-metal oxide like CO₂ — likely missing, but closest expected: acidic oxide = CO₂) 9. B (Hydrogen) 10. B (NaOH) 11. C (3) 12. C (Iron) 13. B (Sublimation) 14. C (Helium) 15. B (Na₂CO₃·10H₂O) 16. C (Nitrogen oxide) 17. C (Increases reaction rate) 18. C (Sulphuric acid) 19. C (Carbon monoxide) 20. D (Oxygen and water) 21. C (Ethene) 22. A (CₙH₂ₙ₊₂) 23. C (NH₃) 24. B (7) 25. C (Aluminium) 26. A (Bronze) 27. B (Oxidation occurs) 28. C (NaCl) 29. D (Helium) 30. B (NH₃) 31. B (Protons) 32. A (Limewater) 33. B (Temporary hardness) 34. A (Na₂O) 35. C (Bauxite) 36. C (H₂O) 37. B (Iron) 38. C (Carbon dioxide) 39. C (Sodium chloride) 40. C (Sodium) 41. C (Quicklime) 42. B (-OH) 43. D (All of the above) 44. C (CH₃COOH) 45. D (Methane) 46. C (Fluorine) 47. B (Neutralization) 48. C (HCl) 49. A (Sodium carbonate) 50. B (NO₂)

Section B instruction says: Answer Question 1 and any other THREE (3) questions So in total, a student should answer: • Question 1 (compulsory) • Plus any 3 out of Questions 2–6 👉 That means 4 questions altogether

Section B (Theory): ⸻ 1(a) Definitions (i) Atom: The smallest particle of an element that can take part in a chemical reaction. (ii) Mole: The amount of substance containing 6.02 \times 10^{23} particles (Avogadro’s number). (iii) Relative atomic mass (Ar): The average mass of an atom of an element compared to \frac{1}{12} of the mass of a carbon-12 atom. ⸻ 1(b) Calculation Molar mass of CO₂ = 12 + (16 × 2) = 44 g/mol Number of moles = \frac{22.0}{44} = 0.5 \text{ mol} Answer: 0.5 mol ⸻ 1(c) Differences between mixture and compound • Mixture can be separated by physical means; compound cannot. • Mixture retains properties of components; compound has new properties. ⸻ 1(d) Electrolysis Electrolysis is the chemical decomposition of a substance using electric current. ⸻ 1(e) Electrolysis of Acidified Water (i) Labelled diagram (description): • Two electrodes (anode and cathode) dipped in acidified water • Connected to a battery • Test tubes inverted over each electrode to collect gases (ii) Observations: • Gas is produced at both electrodes • Volume of gas at cathode is twice that at anode • Cathode gas burns with a “pop” (hydrogen) • Anode gas rekindles a glowing splint (oxygen) (iii) Conclusion: Water decomposes into hydrogen and oxygen in a ratio of 2:1. ⸻ 1(f) Uses • Hydrogen: used in manufacture of ammonia / as fuel • Oxygen: used for breathing / welding ⸻ 2(a) Definitions (i) Acid: Substance that donates protons (H⁺ ions). (ii) Base: Substance that accepts protons or produces OH⁻ ions. (iii) Salt: Substance formed when acid reacts with a base. ⸻ 2(b) Reaction of zinc with HCl Zinc + Hydrochloric acid → Zinc chloride + Hydrogen Balanced equation: Zn + 2HCl → ZnCl_2 + H_2 ⸻ 2(c) Two methods of preparing soluble salts • Titration (acid + alkali) • Reaction of acid with metal / oxide / carbonate ⸻ 2(d) Rusting of iron Rusting is the gradual destruction of iron due to reaction with oxygen and water. ⸻ 2(e) Conditions for rusting • Presence of oxygen • Presence of water ⸻ 2(f) Prevention of rusting • Painting • Galvanizing ⸻ 2(g) Why aluminium does not rust easily Aluminium forms a protective oxide layer that prevents further corrosion. ⸻ 3(a) Homologous series A family of organic compounds with similar chemical properties and same general formula. ⸻ 3(b) General formula • Alkanes: CₙH₂ₙ₊₂ • Alkenes: CₙH₂ₙ ⸻ 3(c) Complete combustion of ethanol Products: • Carbon dioxide (CO₂) • Water (H₂O) ⸻ 3(d) Uses of ethanol • As fuel • As solvent ⸻ 3(e) Hard water Water that does not lather easily with soap due to dissolved salts. ⸻ 3(f) Differences Temporary hardness: • Caused by bicarbonates • Removed by boiling Permanent hardness: • Caused by sulphates/chlorides • Not removed by boiling ⸻ 3(g) Removal of temporary hardness • By boiling (precipitates calcium carbonate) ⸻ 3(h) Disadvantages of hard water • Wastes soap • Causes scale in kettles/boilers

*OYO STATE MOCK CHEMISTRY BELOW 👇*