WAEC 2026

WAEC Chemistry (OBJ & Essay) Questions and Answers 2026

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Objective Answers (OBJ)

Essay & Theory Answers

Verified step-by-step detailed explanations

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*CHEMISTRY OBJECTIVE* 1–10: B C C A C A B D A D 11–20: B A C D C A D A A B 21–30: B D D A A A C B C B 31–40: A A B B D C D B A D 41–50: A A D C A D D C A B *USE THIS IS URS IS RESHUFFLED* 1. B – Using combined gas law: P₁V₁/T₁ = P₂V₂/T₂. P₂ = 2P₁, T₂ = ½T₁ → V₂ = 50 cm³. 2. C – 1s²2s²2p³ → 7 electrons, Period 2, C is correct. 3. C – X³⁺ with Cl⁻ → XCl₃. 4. A – Zwitterion is bipolar (both + and – charges). 5. C – Transition elements have variable oxidation states due to partially filled d-orbitals. 6. A – O₂ and O₃ are allotropes. 7. B – Soapy touch → alkaline → pH 12. 8. D – Iron rod is pure substance (element), not a mixture. 9. A – Sucrose (glucose + fructose). 10. D – K atom (1s²2s²2p⁶3s²3p⁶4s¹) → no 3d electrons. 11. B – CO₂ from glucose by fermentation. 12. A – NaCl less soluble → crystallizes first. 13. C – Metals conduct due to mobile electrons. 14. D – ²⁷₁₃X → protons=13, neutrons=14, electrons=13 → total subatomic particles = 40. 15. C – Sour taste → acidic → pH 5. 16. A – Atomic radius increases right to left. 17. D – Yellow flame → sodium (Na). 18. A – Same T & P, equal volumes → same number of molecules (Avogadro). 19. A – Planting trees reduces greenhouse effect (CO₂ absorption). 20. B – Balance: C₄H₈ + ?O₂ → 4CO₂ + 4H₂O → O₂ = (8+4)/2 = 6? 21. B – Dalton's law: total pressure = sum partial pressures. 22. D – C forms CX₄ and CY₄ → X and Y both monovalent → X and Y form XY or YX. D. 23. D – Zinc (galvanization). 24. A – FeCl₂: 56 + 71 = 127 g/mol. 25. A – Funnel for transferring into burette. 26. A – Fe³⁺ (reddish-brown) to Fe²⁺ (pale-green) → reduction → LiAlH₄ (reducing agent). 27. C – Brine is mixture (salt + water). 28. B – Cl to Cl⁻ → gain electron → ionization (or reduction). Options: ionization is correct here. 29. C – C₂H₅O = 2×12 + 5×1 + 16 = 24+5+16 = 45. Times 2 for (C₂H₅O)₂ → 90. Options: 88 → C₄H₁₀O₂? But empirical mass 45, n=88/45≈2 → molecular C₄H₁₀OSo answer C = 88. 30. B – Molecule = smallest independent particle of an element or compound. Best here: element. 31. A – HCl most volatile. 32. A – Balance charge: Left: -2, Right: -4 + 4H⁺ (+4) + Xe → net right = Xe, Xe must be 2e⁻. So A=2. 33. B – Simplest ratio = empirical formula. 34. B – KCl essential for plant growth. 35. D – Moles = 2.0 × 0.25 = 0.5 mol. Mass = 0.5 × 40 = 20 g. 36. C – Ethanol from sugar cane (fermentation). 37. D – X²⁺ → lose 2 electrons. 38. B – Cu₂S → 2Cu + S²⁻ → Cu⁺ loses electron to become Cu → Cu₂S has lost electrons. 39. A – 13 protons, 10 electrons → +3 charge → cation. 40. D – MgO is basic oxide. 41. A – Degenerate orbitals = same subshell, same energy. 42. A – Alkyl = CₙH₂ₙ₊₁. 43. D – HCl is covalent. 44. C – CO is poisonous. 45. A – Zn evolves H₂ most rapidly from dilute HCl. 46. D – Combustion and neutralization are always exothermic → ΔH negative. 47. D – MgCl₂ + 2H₂O → Mg(OH)₂ + 2HCl is hydrolysis. 48. C – Weak acid that changes color → acid-base indicator. 49. A – CO₂ has polar bonds but non-polar molecule. 50. B – Calcium chloride purifies ethanol (removes water). https://t.me/freewassceditto *REACT, SHARE AND FORWARD TO EVERYONE ❤️🔥* FOR WAEC EXPO 24HRS BEFORE EXAM, MESSAGE ME ON TELEGRAM👇👇: https://t.me/Officialkingjay1 JOIN OUR VIP CHANNEL 👇🏻👇🏻 https://t.me/allexamexporunz Neco vip 👇👇 https://t.me/necovipanswer JOIN OUR VIP CHANNEL 👇🏻👇🏻 https://t.me/examgroupng *WAEC CHEMISTRY* *NUMBER ONE* (1ai) Suspension: (PICK ANY ONE) (i) Muddy water (ii) Chalk in water (iii) Sand in water (iv) Flour in water (v) Clay in water (1aii) Colloid: (PICK ANY ONE) (i) Milk (ii) Fog (iii) Smoke (iv) Jelly (v) Starch solution (1b) Isoelectronic series is a group of atoms, ions or molecules having the same number of electrons and the same electronic configuration. (1ci) Heat of formation is the heat change when one mole of a compound is formed from its constituent elements in their standard states. (1cii) Heat of combustion is the heat change when one mole of a substance is completely burnt in excess oxygen. (1d) Helium is preferred because it is chemically inert and non-flammable, whereas hydrogen is highly flammable and can easily explode when mixed with air. (1e) (i) CO₂: Linear (ii) CH₄: Tetrahedral (iii) NH₃: Trigonal pyramidal (1f) (i) sulphur (ii) Phosphorus (1g) (PICK ANY THREE) (i) They exhibit variable oxidation states. (ii) They form coloured compounds. (iii) They act as catalysts. (iv) They form complex ions. (v) They have high melting and boiling points. (vi) They are good conductors of heat and electricity. (vii) They are hard and dense metals. (1h) (i) Aluminium (ii) Sodium (1i) Atomic number is the atomic number is the number of protons in the nucleus of an atom and is equal to the number of electrons in a neutral atom. (1j) (i) Covalent bond (ii) Coordinate (dative) bond (iii) Ionic bond *WAEC CHEMISTRY (PAPER 2 – ESSAY)* *COMPLETE ANSWERS – QUESTIONS 2, 3, 4 & 5* =========================================================== https://t.me/freewassceditto *REACT, SHARE AND FORWARD TO EVERYONE ❤️🔥* FOR WAEC EXPO 24HRS BEFORE EXAM, MESSAGE ME ON TELEGRAM👇👇: https://t.me/Officialkingjay1 JOIN OUR VIP CHANNEL 👇🏻👇🏻 https://t.me/allexamexporunz Neco vip 👇👇 https://t.me/necovipanswer JOIN OUR VIP CHANNEL 👇🏻👇🏻 https://t.me/examgroupng QUESTION 2 =========================================================== (a) Periodic table positions (using given letters) Assuming O = Group I, R = Group II, T = Group III, M = Group IV, V = Group VIII (Noble gas) (i) Which element would exist as a diatomic gas? Answer: A halogen (Group VII element) – not explicitly shown in the table. If a halogen were present, it would be the answer. (ii) Which is an alkali metal? Answer: O (Group I) (iii) Which would form an amphoteric oxide? Answer: T (Group III – e.g., aluminium oxide is amphoteric) (iv) Which would combine with M to form electrovalent bonds? Answer: O or R (Group I or Group II metals) (v) Which is a noble gas? Answer: V (Group VIII) (vi) Which would form a covalent oxide? Answer: M (Group IV – e.g., CO₂, SiO₂ are covalent oxides) =========================================================== (b)(i) Define the term saturated solution (2 marks) A saturated solution is a solution in which no more solute can dissolve at a given temperature. The solution is in equilibrium with undissolved solute. =========================================================== QUESTION 3 =========================================================== (a)(i) Define the term enthalpy of neutralization (2 marks) Enthalpy of neutralization is the heat change that occurs when one mole of hydrogen ions (H⁺) from an acid reacts completely with one mole of hydroxide ions (OH⁻) from a base to form one mole of water under standard conditions. (ii) Write the ionic equation for neutralization (1 mark) H⁺(aq) + OH⁻(aq) → H₂O(l) =========================================================== (b) Reaction scheme (propanoic acid) (i) Identify W, X, Y and Z (4 marks) W = C₂H₅MgBr (ethyl magnesium bromide – a Grignard reagent) X = Ethyl propanoate (C₂H₅COOC₂H₅) Y = Propan-1-ol (C₂H₅CH₂OH) Z = Propene (CH₃CH=CH₂) (ii) Write the equation for the reaction between propanoic acid and ethanol (2 marks) C₂H₅COOH + C₂H₅OH ⇌ C₂H₅COOC₂H₅ + H₂O (Concentrated H₂SO₄ catalyst, heat) =========================================================== (c)(i) What is an acid anhydride? (2 marks) An acid anhydride is a compound formed by the removal of water from two molecules of a carboxylic acid (or from one molecule of a dicarboxylic acid). Example: ethanoic anhydride (CH₃CO)₂O. (ii) Write the ionic equation for the reaction between propanoic acid and ethanol (1 mark) The reaction is esterification (covalent). If an ionic equation is required, there is none because all species are molecular. The molecular equation is given in 3(b)(ii) above. =========================================================== QUESTION 4 =========================================================== (a)(i) Describe briefly the chemical test for hydrogen (3 marks) A lighted splint is brought near the gas. Hydrogen burns with a characteristic "pop" sound. This is because hydrogen is highly flammable and reacts explosively with oxygen in the air to form water. (ii) Mention three uses of hydrogen gas (3 marks) 1. Hydrogen is used in the Haber process for the manufacture of ammonia (NH₃), which is used to produce fertilisers. 2. Hydrogen is used as a rocket fuel because it burns with high energy and produces only water as a by-product. 3. Hydrogen is used in the hydrogenation of vegetable oils to produce margarine and cooking fats (turning liquid oils into semi-solid fats). (iii) Write the equation for the reaction of hydrogen with: (3 marks) (I) Sodium metal 2Na(s) + H₂(g) → 2NaH(s) (sodium hydride) (II) Copper (II) chloride solution CuCl₂(aq) + H₂(g) → Cu(s) + 2HCl(aq) (Hydrogen reduces copper(II) chloride to metallic copper) (III) Chlorine gas H₂(g) + Cl₂(g) → 2HCl(g) (Hydrogen burns in chlorine to produce hydrogen chloride gas) =========================================================== (b)(i) Give the reason why: (2 marks) (I) Tin is used in the canning of food Tin is used because it is non-toxic and resistant to corrosion. It also does not react with most food acids, preventing the food from being contaminated and the can from rusting. Tin is usually coated on steel (tinplate). (II) Copper is used in the manufacture of wires Copper is used because it has very high electrical conductivity (second only to silver) and is relatively cheap. It is also ductile, meaning it can be drawn into thin wires without breaking. (ii) Name one ore of: (2 marks) (I) Iron Haematite (Fe₂O₃) – also acceptable: Magnetite (Fe₃O₄), Limonite, Siderite (II) Tin Cassiterite (SnO₂) (iii) Name one alloy of: (2 marks) (I) Iron Steel (iron + carbon) – also acceptable: Stainless steel (iron + carbon + chromium), Cast iron (II) Copper Brass (copper + zinc) – also acceptable: Bronze (copper + tin), Cupronickel =========================================================== (c) Destructive distillation of coal (from previous image) (i) Name the solid Answer: Coke (ii) Write an equation for the reaction of coke with steam C(s) + H₂O(g) → CO(g) + H₂(g) (water gas reaction) (iii) Name the gaseous fuel obtained Answer: Water gas (mixture of carbon monoxide and hydrogen) or synthesis gas =========================================================== (d)(i) Method of extraction of each metal (from previous image) (I) Tin – Carbon reduction (smelting) of tin(IV) oxide (cassiterite) (II) Iron – Blast furnace (carbon reduction of iron ore) (III) Aluminium – Electrolysis of molten aluminium oxide (Al₂O₃) in cryolite (ii) State one use of aluminium Answer: Manufacture of aircraft parts, cooking utensils, window frames, or drinks cans =========================================================== QUESTION 5 =========================================================== (a) Treatment of water for community supply (from previous image) (i) State the process that: (3 marks) (I) Removes earthy particles from water – Sedimentation (or filtration) (II) Causes fine insoluble solids to clump together – Coagulation (or flocculation) (III) Increases the amount of dissolved oxygen in water – Aeration (ii) State the substance added to water to: (4 marks) (I) Kill germs – Chlorine (or sodium hypochlorite) (II) Increase its pH – Lime (calcium hydroxide) or sodium hydroxide (III) Prevent goitre – Iodine (or potassium iodide) (IV) Precipitate solid impurities – Alum (aluminium sulphate) =========================================================== (b) Chlorine and its compounds (from previous image) (i) Reagent that produces chlorine gas when added to: (2 marks) (I) MnO₂(s) – Concentrated hydrochloric acid (conc. HCl) (II) A mixture of dil. H₂SO₄ and NaCl(aq) – Manganese dioxide (MnO₂) or potassium permanganate (KMnO₄) (ii) Name the main products of the reaction of chlorine with: (2 marks) (I) Cold dilute NaOH – Sodium chloride (NaCl) and sodium hypochlorite (NaOCl) (II) Freshly prepared Ca(OH)₂(aq) – Bleaching powder (calcium hypochlorite, Ca(OCl)₂) and calcium chloride (iii) State the application of the product in laundry (1 mark) Answer: Bleaching powder (or sodium hypochlorite) is used as a bleaching agent to whiten fabrics and remove stains. =========================================================== (c) Concentrated H₂SO₄ added to NaCl(s) (from previous image) (i) State the condition necessary for the reaction Answer: Heating (the mixture must be heated) (ii) Write the equation for the reaction NaCl(s) + H₂SO₄(conc.) → NaHSO₄(aq) + HCl(g) (On strong heating: 2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl) (iii) Mention the reagent used to identify the gas liberated (HCl gas) Answer: Ammonia solution (NH₃(aq)) or silver nitrate solution (AgNO₃) (iv) State what would be observed With ammonia: Dense white fumes of ammonium chloride (NH₄Cl) With silver nitrate: White precipitate of silver chloride (AgCl) which is insoluble in dilute nitric acid (v) Name the precipitate formed when the gas is bubbled into Pb(NO₃)₂(aq) Answer: Lead(II) chloride (PbCl₂) – white precipitate =========================================================== (d) Copper sulphate and bronze (from previous image) (i) Describe briefly how CuSO₄ crystals could be obtained from its aqueous solution Answer: The aqueous solution is heated to evaporate some water until it becomes saturated. The concentrated solution is then allowed to cool slowly. As it cools, blue copper(II) sulphate pentahydrate (CuSO₄·5H₂O) crystals form. The crystals are filtered off and dried between filter papers. (ii) State the constituent elements in bronze Answer: Copper (Cu) and tin (Sn) ===========================================================