2026 WAEC
Thursday 11th June 2026
Chemistry
Exam Pluto
PIN: 871
Click here to refresh for new updates
CHEMISTRY WAEC QUESTIONS AND ANSWERS POSTED BELOW
CHEMISTRY WAEC ESSAY
👇👇👇👇👇👇👇👇👇👇👇👇👇👇
*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*
*NUMBER TWO*
(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"
(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⁻³
(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).
3(a)(i)
Enthalpy of neutralization is the energy change when an acid reacts with a base to form one mole of water under standard conditions.
3(a)(ii)
H⁺(aq) + OH⁻(aq) → H₂O(l)
3(b)(i)
W: Sodium propanoate (CH₃CH₂COONa)
X: Ethyl propanoate (CH₃CH₂COOC₂H₅)
Y: Propan-1-ol (CH₃CH₂CH₂OH)
Z: Propene (CH₃CH=CH₂)
3(b)(ii)
CH₃CH₂COOH + C₂H₅OH ⇌ CH₃CH₂COOC₂H₅ + H₂O
(in the presence of concentrated H₂SO₄ catalyst)
3(c)(i)
An acid anhydride is a compound formed by the removal of one molecule of water from two molecules of a carboxylic acid. It has the general formula (RCO)₂O.
3(c)(ii)
(I) H₂SO₄ → SO₃
(II) HNO₃ → N₂O₅
(III) H₂CO₃ → CO₂
3(d)(i)
Al₂O₃ is dissolved in molten cryolite (Na₃AlF₆) to lower the melting point from about 2050°C to around 950°C. The molten mixture is electrolyzed using carbon (graphite) electrodes. At the cathode, aluminium ions are reduced: Al³⁺ + 3e⁻ → Al. Molten aluminium, being denser, sinks and collects at the bottom of the cell. At the anode, oxide ions are oxidized: 2O²⁻ → O₂ + 4e⁻.
3(d)(ii)
Carbon (graphite) electrodes.
3(d)(iii)
The oxygen produced at the anode reacts with the carbon anode at high temperature to form carbon dioxide (C + O₂ → CO₂), gradually burning it away, so it must be replaced periodically.
3(e)(i)
Using Graham's law: rateX / rateO₂ = √(M(O₂) / M(X))
2 = √(32 / M(X))
4 = 32 / M(X)
M(X) = 32 / 4 = 8 g/mol
3(e)(ii)
Moles of X = 5 / 22.4 = 0.2232 mol
Mass = 0.2232 × 8 = 1.79 g
4(a)(i)
Introduce a burning splint into the gas. Hydrogen burns with a "pop" sound.
4(a)(ii)
It is used in the Haber process for manufacturing ammonia.
It is used in the hydrogenation of vegetable oils to produce margarine.
It is used as rocket fuel.
4(a)(iii)
(I) 2Na + H₂ → 2NaH
(II) H₂ + CuCl₂ → Cu + 2HCl
(III) H₂ + Cl₂ → 2HCl
4(b)(i)
(I) Tin is resistant to corrosion and does not react with food substances, so it protects the food from contamination.
(II) Copper is an excellent conductor of electricity and is ductile, making it easy to draw into wires.
4(b)(ii)
(I) Haematite (Fe₂O₃)
(II) Cassiterite (SnO₂)
4(b)(iii)
(I) Steel
(II) Brass
4(c)(i)
Coke
4(c)(ii)
C + H₂O → CO + H₂
4(c)(iii)
Water gas (a mixture of carbon monoxide and hydrogen)
4(d)(i)
(I) Tin — reduction of its ore with carbon/coke
(II) Iron — reduction of its ore with carbon in a blast furnace
(III) Aluminium — electrolysis of its molten ore (electrolytic reduction)
4(d)(ii)
It is used in making cooking utensils and aircraft bodies.
*2026 WAEC CHEMISTRY ANSWERS*
(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)