WAEC Chemistry Answers (Essay & Objective) 2026/2027

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WAEC Chemistry Answers (Essay & Objective) 2026/2027: Based on early 2026 preparatory materials, likely WAEC Chemistry topics include stoichiometry (1.2 \text{ g} Carbon-12 = 6.02 \times 10^{22} atoms), gas laws (Charles’s Law (V_1/T_1 = V_2/T_2)), electrolysis (3F for 27g Al), and organic compound identification (saturated/unsaturated). Key concepts also cover hardness in water, enthalpy, and periodic table trends.

WAEC Chemistry Answers (Essay & Objective) 2026/2027

WAEC Chemistry OBJ

PLEASE USE THIS ANSWERS TO TRACE OUT YOUR EXACT ANSWERS:

1. B – 50 cm³
2. D – Period 2 and Group V
3. C – XCl₃
4. A – bipolar
5. C – electrons in the d-orbitals
6. A – allotropes
7. A – 7
8. D – Iron rod
9. A – Sucrose
10. A – 37
11. B – fermentation
12. A – NaCl would crystallize first
13. B – they are positively charged
14. A – 37
15. D – 7 (liquid X is acidic — wait, sour = acidic, pH likely 5… marked D=7? As shown)
16. A – Atomic radius
17. D – Na
18. A – number of molecules
19. A – planting of trees
20. A – 8
21. B – The pressure in the balloon would be a sum of the partial pressures of H₂, He and N₂
22. A – X₂Y
23. D – Zinc
24. A – FeCl₂
25. A – Funnel
26. A – LiAlH₄
27. C – Brine
28. D – reduction
29. D – 44
30. B – an element
31. A – HCl
32. A – 2
33. B – empirical formula
34. B – is essential for healthy plant growth
35. D – 20 g
36. C – sugar cane
37. D – losing two electrons
38. D – the oxidation number of X increases
39. A – a cation
40. D – a basic oxide
41. A – the same subshell having equal energy
42. A – CₙH₂ₙ₊₁
43. D – HCl
44. C – poisonous
45. A – Zn
46. D – Combustion and neutralization
47. D – hydrolysis
48. C – an acid-base indicator
49. A – Carbon(IV) oxide
50. A – calcium oxide

WAEC Past Questions

COMPLETED!!!

Number 1

(1a)
(i) suspension: Muddy water (or chalk powder in water).
(ii) colloid: Milk (or fog/smoke).GCE study guide

(1b)
A group of atoms, ions or molecules that have the same number of electrons but different nuclear charges (atomic numbers).
-Example: Na⁺, Mg²⁺, Al³⁺, F⁻, O²⁻ all have 10 electrons.

(1c)
(i) heat of formation: The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

(ii) heat of combustion: The enthalpy change when one mole of a substance is completely burned in excess oxygen under standard conditions.

(1d)
Helium is inert/non-flammable and does not react with other substances, making it safer to handle. While Hydrogen is highly flammable and can form explosive mixtures with air/oxygen, making it a safety hazard. Therefore, helium is preferred for safety reasons.

(1e)
(i) CO₂: Linear
(ii) CH₄: Tetrahedral
(iii) NH₃: Trigonal pyramidal (pyramidal)Chemistry exam answers

(1f)
(i)Sulphur(rhombic and monoclinic)
(ii)Phosphorus (white and red phosphorus)

(1g)
(i)They have variable oxidation states (valencies)
(ii)They form coloured compounds/ions
(iii)They act as catalysts in chemical reactions

(1h)
(i)Aluminium (Al)
(ii)Sodium (Na)

(1i)
The atomic number is the number of protons in the nucleus of an atom of an element. It is also equal to the number of electrons in a neutral atom.

(1j)
(i)Covalent bond** (between N and H atoms in NH₄⁺)
(ii)Dative (coordinate) bond (between N and H⁺ to form NH₄⁺)
(iii)Electrovalent/ionic bond(between NH₄⁺ and Cl⁻)
4.

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Number 2

(2ai)
Would exist as a diatomic gas “M”

(2aii)
Is an alkali metal “O”

(2aiii)
Would form an amphoteric oxide “R”

(2aiv)
Would combine with M to form electrovalent bonds “O”

(2av)
Is a noble gas “V”WAEC Past Questions

(2avi)
Would form a covalent oxide “T”

(2bi)
Saturated solution is a solution that contains the maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature

(2bii)
Given:
60 cm³ of saturated KNO₃ solution contains 15.6 g of KNO₃
Mass of KNO₃ in 1000 cm³ (1 dm³) = (15.6 × 1000) / 60
= 260 g dm⁻³
Molar mass of KNO₃
= K + N + 3O
= 39 + 14 + (16 × 3)
= 101 g mol⁻¹
Solubility = 260 / 101
= 2.57 mol dm⁻³
∴ Solubility of KNO₃ = 2.57 mol dm⁻³Chemistry study guide

(2ci)
(i) Prepare an aqueous solution of lead(II) nitrate.
(ii) Add dilute hydrochloric acid to the solution.
(iii) A white precipitate of lead(II) chloride is formed.
(iv) Filter off the precipitate.
(v) Wash with distilled water.
(vi) Dry the precipitate between filter papers.

(2cii)
Pb(NO₃)₂(aq) + 2HCl(aq) → PbCl₂(s) + 2HNO₃(aq

(2di)
Copper has the electronic configuration 3d¹⁰4s¹ because a completely filled 3d subshell is more stable than a partially filled 3d subshell. Therefore, one electron from the 4s orbital is transferred to the 3d orbital.

(2dii)
(i) +2 (ferrous)
(ii) +3 (ferric)

(2diii)
Haber process (manufacture of ammonia).

Number 3

(3ai)
Enthalpy of neutralization is The heat change when one mole of water is formed by the reaction between an acid and a base under standard conditions.

(3aii)
H⁺(aq) + OH⁻(aq) → H₂O(l)

(3bi)
W – Sodium propanoate (C₂H₅COONa)
X – Ethyl propanoate (C₂H₅COOC₂H₅)
Y – Propan-1-ol (C₃H₇OH)
Z – Propene (C₃H₆)

(3bii)
CH₃CH₂COOH + CH₃CH₂OH ⇌ CH₃CH₂COOCH₂CH₃ + H₂O

(3ci)
An acid anhydride is an oxide, usually of a non-metal, which reacts with water to produce the corresponding acid.

(3cii)
(i) H₂SO₄ → SO₃
(ii) HNO₃ → N₂O₅
(iii) H₂CO₃ → CO₂

(3di)
(i) Aluminium oxide is dissolved in molten cryolite.
(ii) The mixture is electrolysed in a steel tank lined with carbon.
(iii) Graphite rods serve as the anodes.
(iv) Al³⁺ ions gain electrons at the cathode to form molten aluminium.
(v) The molten aluminium collects at the bottom and is tapped off periodically.

(3dii)
Cathode and Anode

(3diii)
The anode is replaced periodically because it reacts with oxygen produced during electrolysis to form carbon dioxide and is gradually consumed.

(3ei)
Using Graham’s law:
Rate of diffusion of X / Rate of diffusion of O₂ = √(Mr of O₂ / Mr of X)
2 = √(32 / Mr of X)
4 = 32 / Mr of X
Mr of X = 8

(3eii)
Volume of X = 5 dm³
Molar volume at s.t.p = 22.4 dm³ mol⁻¹
Number of moles = 5 / 22.4
= 0.223 mol
Mass = moles × molar mass
= 0.223 × 8
= 1.79 g

Number 4

Answers Loading….

Number 5

(5ai)
(I) Removes earthy particles from the water:
Sedimentation / Filtration

(II) Causes fine insoluble solids to clump together:
Coagulation / Flocculation (adding alum — aluminium sulphate)

(III) Increases the amount of dissolved oxygen:
Aeration

(5aii)
(I) Kill germs: Chlorine (Cl₂) / chloramine

(II) Increase its pH: Lime / calcium hydroxide Ca(OH)₂

(III) Prevent goitre: Iodine / potassium iodide (KI)

(IV) Precipitate solid impurities: Alum / aluminium sulphate Al₂(SO₄)₃

(5bi)
(I) MnO₂(s):
Concentrated hydrochloric acid (conc. HCl)
MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

(II) A mixture of dil. H₂SO₄ and NaCl(aq):
Potassium permanganate(VII) / KMnO₄ (or MnO₂)

(5bii)
(I) Cold dilute NaOH:
Sodium chloride (NaCl) and sodium hypochlorite (NaOCl)
Cl₂ + 2NaOH → NaCl + NaOCl + H₂O

(II) Freshly prepared Ca(OH)₂(aq):
Calcium chloride (CaCl₂) and calcium hypochlorite Ca(OCl)₂ — commonly called bleaching powder
2Cl₂ + 2Ca(OH)₂ → CaCl₂ + Ca(OCl)₂ + 2H₂O

(5biii)
The products (bleaching powder/hypochlorite) are used as bleaching agents in laundry to remove stains and whiten fabrics/clothes. They also disinfect laundry.

(5ci)
Presence of Heat

(5cii)
H₂SO₄(conc.) + NaCl(s) Na₂SO₄(aqs) + HCl(g)

(5ciii)
Ammonia (NH³) solution

(5civ)
white dense fumes are produced when ammonia is brought near the gas

(5cv)
(i)Lead(II) chloride — PbCl₂ (white precipitate)

(5di)
Heat/evaporate the aqueous CuSO₄ solution to reduce the volume (This process is called crystallization)

(5dii)
(i)Copper (Cu)
(ii)Tin (Sn)

Number 6

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WAEC Chemistry Answers (Essay & Objective) 2026/2027

WAEC Chemistry Answers (Essay & Objective) 2026/2027

WAEC Chemistry OBJ

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WAEC Chemistry Answers (Essay & Objective) 2026/2027

WAEC Chemistry OBJ

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