WAEC 2026 Chemistry 1 (OBJ) \\u2014 Answers

Use this quick-reference table for all 50 WAEC 2026 Chemistry 1 (OBJ) answers, then scroll down for full explanations.

Questions	Answers
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

OBJ Answer Explanations

B – Combined gas law: P₂ = 2P₁, T₂ = \\xbdT₁ \\u2192 V₂ = 50 cm³.
C – 1s²2s²2p³ \\u2192 7 electrons, Period 2.
C – X³⁺ with Cl⁻ \\u2192 XCl₃.
A – Zwitterion is bipolar (both positive and negative charges).
C – Transition elements have variable oxidation states due to partially filled d-orbitals.
A – O₂ and O₃ are allotropes.
B – Soapy touch indicates an alkaline solution with pH about 12.
D – An iron rod is a pure substance (element), not a mixture.
A – Sucrose is formed from glucose and fructose.
D – A potassium atom has no 3d electrons.
B – CO₂ from glucose by fermentation.
A – NaCl is less soluble and crystallizes first.
C – Metals conduct electricity due to mobile electrons.
D – For \\u00b2\\u2077\\u2081\\u2083X: protons = 13, neutrons = 14, electrons = 13 \\u2192 total subatomic particles = 40.
C – Sour taste indicates an acidic solution with pH about 5.
A – Atomic radius increases from right to left across a period.
D – Yellow flame in a flame test indicates sodium (Na).
A – At the same temperature and pressure, equal volumes of gases contain the same number of molecules (Avogadro’s law).
A – Planting trees reduces the greenhouse effect by absorbing CO₂.
B – Correct balancing of C₄H₈ combustion.
B – Dalton’s law: total pressure equals the sum of partial pressures.
D – C forms CX₄ and CY₄; both X and Y are monovalent and combine to form XY.
D – Zinc is used for galvanization.
A – Relative molecular mass of FeCl₂: 56 + 71 = 127 g mol⁻¹.
A – A funnel is used for transferring liquid into a burette.
A – Fe³⁺ (reddish-brown) to Fe²⁺ (pale green) is reduction; LiAlH₄ is the reducing agent.
C – Brine is a mixture of salt and water.
B – Cl to Cl⁻ involves gain of an electron, which is reduction (ion formation).
C – Empirical formula mass C₂H₅O = 45; n = 2, so molecular formula C₄H₁₀O and molar mass 88 g mol⁻¹.
B – A molecule is the smallest independent particle of an element or compound.
A – HCl is the most volatile among the options.
A – Balancing the redox half-equation gives a coefficient of 2.
B – The simplest ratio of atoms gives the empirical formula.
B – KCl is essential for plant growth.
D – Moles = 2.0 \\xd7 0.25 = 0.5 mol; mass = 0.5 \\xd7 40 = 20 g.
C – Ethanol is obtained from sugar cane by fermentation.
D – X²⁺ means the atom has lost two electrons.
B – In Cu₂S, copper loses electrons, so it is oxidized.
A – 13 protons and 10 electrons give a +3 charge, so it is a cation.
D – MgO is a basic oxide.
A – Degenerate orbitals belong to the same subshell and have the same energy.
A – General formula for an alkyl group is C_nH_2n+1.
D – HCl is a covalent compound.
C – CO is a poisonous gas.
A – Zinc evolves hydrogen gas most rapidly from dilute HCl.
D – Combustion and neutralization reactions are always exothermic (\\u0394H negative).
D – MgCl₂ + 2H₂O \\u2192 Mg(OH)₂ + 2HCl is hydrolysis.
C – A weak acid that changes colour is an acid–base indicator.
A – CO₂ has polar bonds but is a non-polar molecule due to its linear shape.
B – Calcium chloride is used to purify ethanol by removing water.

2026 WAEC Chemistry 2 Questions and Answers (Essay/Theory)

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WAEC 2026 Chemistry 1 (OBJ) \\u2014 Question Paper

Scroll through the full Chemistry 1 OBJ question paper pages below.

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WAEC 2026 Chemistry 2 — Question 1 Answers

(1a)(i) Suspension (any one):

Muddy water
Chalk in water
Sand in water
Flour in water
Clay in water

(1a)(ii) Colloid (any one):

Milk
Fog
Smoke
Jelly
Starch solution

(1b) Isoelectronic series is a group of atoms, ions or molecules having the same number of electrons and the same electronic configuration.

(1c)(i) Heat of formation is the heat change when one mole of a compound is formed from its constituent elements in their standard states.

(1c)(ii) 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) Shapes of molecules:

CO₂: Linear
CH₄: Tetrahedral
NH₃: Trigonal pyramidal

(1f) Elements that exist as allotropes:

Sulphur
Phosphorus

(1g) Properties of transition metals (any three):

They exhibit variable oxidation states.
They form coloured compounds.
They act as catalysts.
They form complex ions.
They have high melting and boiling points.
They are good conductors of heat and electricity.
They are hard and dense metals.

(1h) Metals that are extracted by electrolysis:

Aluminium
Sodium

(1i) 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) Types of bonds in water (H₂O):

Covalent bond
Coordinate (dative) bond
Ionic bond

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WAEC 2026 Chemistry 2 \\u2014 Question 2 Answers

(2a) Periodic Table — Element Identification

Sub-question	Answer
(i) Would exist as a diatomic gas	M
(ii) Is an alkali metal	O
(iii) Would form an amphoteric oxide	R
(iv) Would combine with M to form electrovalent bonds	O
(v) Is a noble gas	V
(vi) Would form a covalent oxide	T

(2b)(i) A 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.

(2b)(ii) Calculation:

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

&therefore; Solubility of KNO₃ = 2.57 mol dm^-3

(2c)(i) Preparation of lead(II) chloride:

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

(2c)(ii) Equation: Pb(NO₃)₂(aq) + 2HCl(aq) → PbCl₂(s) + 2HNO₃(aq)

(2d)(i) 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.

(2d)(ii) Oxidation states of iron:

+2 (ferrous)
+3 (ferric)

(2d)(iii) Iron is used as a catalyst in the Haber process (manufacture of ammonia).

WAEC 2026 Chemistry 2 — Question 3 Answers

(3a)(i) Enthalpy of neutralization is the energy change when an acid reacts with a base to form one mole of water under standard conditions.

(3a)(ii) H⁺(aq) + OH⁻(aq) → H₂O(l)

(3b)(i)

W: Sodium propanoate (CH₃CH₂COONa)
X: Ethyl propanoate (CH₃CH₂COOC₂H₅)
Y: Propan-1-ol (CH₃CH₂CH₂OH)
Z: Propene (CH₃CH=CH₂)

(3b)(ii) CH₃CH₂COOH + C₂H₅OH ↔ CH₃CH₂COOC₂H₅ + H₂O (in the presence of concentrated H₂SO₄ catalyst)

(3c)(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.

(3c)(ii)

(I) H₂SO₄ → SO₃
(II) HNO₃ → N₂O₅
(III) H₂CO₃ → CO₂

(3d)(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⁻.

(3d)(ii) Carbon (graphite) electrodes.

(3d)(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.

(3e)(i) Using Graham’s law: rate_X / rate_O₂ = √(M(O₂) / M(X))
2 = √(32 / M(X))
4 = 32 / M(X)
M(X) = 32 / 4 = 8 g mol⁻¹

(3e)(ii) Moles of X = 5 / 22.4 = 0.2232 mol
Mass = 0.2232 × 8 = 1.79 g

WAEC 2026 Chemistry 2 — Question 4 Answers

(4a)(i) Introduce a burning splint into the gas. Hydrogen burns with a "pop" sound.

(4a)(ii) Uses of hydrogen:

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.

(4a)(iii)

(I) 2Na + H₂ → 2NaH
(II) H₂ + CuCl₂ → Cu + 2HCl
(III) H₂ + Cl₂ → 2HCl

(4b)(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.

(4b)(ii)

(I) Haematite (Fe₂O₃) — ore of iron
(II) Cassiterite (SnO₂) — ore of tin

(4b)(iii)

(I) Steel (alloy of iron)
(II) Brass (alloy of copper)

(4c)(i) Coke

(4c)(ii) C + H₂O → CO + H₂

(4c)(iii) Water gas (a mixture of carbon monoxide and hydrogen)

(4d)(i)

(I) Tin — reduction of its ore (cassiterite) with carbon/coke
(II) Iron — reduction of its ore (haematite) with carbon in a blast furnace
(III) Aluminium — electrolysis of its molten ore (electrolytic reduction)

(4d)(ii) Aluminium is used in making cooking utensils and aircraft bodies.

WAEC 2026 Chemistry 2 — Question 5 Answers

(5a)(i) Stages in water purification:

(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

(5a)(ii) Substances added to water and their purposes:

(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

(5b)(i) Laboratory preparation of chlorine:

(I) Using MnO₂(s): React with concentrated hydrochloric acid (conc. HCl)
Equation: MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
(II) Using a mixture of dilute H₂SO₄ and NaCl(aq): React with potassium permanganate(VII) / KMnO₄ (or MnO₂)

(5b)(ii) Products when chlorine reacts with:

(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

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

(5c)(i) Presence of Heat

(5c)(ii) H₂SO₄(conc.) + 2NaCl(s) → Na₂SO₄(aq) + 2HCl(g)

(5c)(iii) Ammonia (NH₃) solution

(5c)(iv) White dense fumes are produced when ammonia is brought near the gas (HCl).
NH₃(g) + HCl(g) → NH₄Cl(s) (white fumes)

(5c)(v) Lead(II) chloride — PbCl₂ (white precipitate)

(5d)(i) Heat/evaporate the aqueous CuSO₄ solution to reduce the volume, then allow to cool so that CuSO₄·5H₂O crystals form. This process is called crystallization.

(5d)(ii) Composition of bronze:

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