GCE 2026/2027 – CHEMISTRY 1 (OBJECTIVE)
Time: 1 hour
INSTRUCTIONS TO CANDIDATES
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Do NOT open this booklet until you are told to do so.
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This paper consists of 60 multiple-choice objective questions.
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Answer ALL questions.
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Use HB pencil only to shade your answers on the Objective Answer Sheet.
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Shade only one answer per question.
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Erasing must be clean and neat.
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Calculators may be used unless otherwise stated.
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Do not write on the question paper.
Books & Literature
CHEMISTRY 1 (OBJECTIVE) – 60 QUESTIONS
1. The smallest particle of an element that takes part in a chemical reaction is
A. molecule
B. atom
C. ion
D. electron
Answer: B
2. Which of the following is a mixture?
A. Sodium chloride
B. Distilled water
C. Air
D. Carbon dioxide
Answer: C
3. The atomic number of an element is the number of
A. neutrons
B. electrons and protons
C. protons
D. electrons only
Answer: C
4. The relative atomic mass of chlorine is 35.5 because chlorine
A. has two isotopes
B. is diatomic
C. is a gas
D. is reactive
Answer: A
5. Which of the following is a physical change?
A. Burning of paper
B. Rusting of iron
C. Melting of ice
D. Souring of milk
Answer: C
6. The number of atoms in 12 g of carbon-12 is
A. 6.02 × 10²³
B. 1.2 × 10²³
C. 3.01 × 10²³
D. 6.02 × 10²²
Answer: A
7. Which of the following gases is collected by upward delivery?
A. Hydrogen
B. Carbon dioxide
C. Hydrogen chloride
D. Ammonia
Answer: B
WAEC GCE 2026 Chemistry 1 Objective/Essay Questions and Answers
8. The bond formed when two atoms share electrons is
A. ionic
B. metallic
C. covalent
D. coordinate
Answer: C
9. A solution that resists changes in pH is called a
A. salt
B. buffer
C. base
D. neutralizer
Answer: B
10. Which of the following compounds contains both ionic and covalent bonds?
A. NaCl
B. CaO
C. NH₄Cl
D. CO₂
Answer: C
11. The gas that rekindles a glowing splint is
A. hydrogen
B. nitrogen
C. oxygen
D. methane
Answer: C
12. Which of the following is a colligative property?
A. Density
B. Viscosity
C. Boiling point elevation
D. Colour
Answer: C
13. An example of an endothermic reaction is
A. combustion
B. respiration
C. photosynthesis
D. neutralization
Answer: C
14. A catalyst increases the rate of a chemical reaction by
A. lowering activation energy
B. increasing activation energy
C. reducing reactant concentration
D. increasing pressure
Answer: A
15. The pH of a strong acid is
A. 1
B. 7
C. 10
D. 14
Answer: A
16. The process of converting gas directly to solid is
A. melting
B. freezing
C. sublimation
D. deposition
Answer: D
17. The oxidation number of sulphur in H₂SO₄ is
A. +2
B. +4
C. +6
D. –2
Answer: C
18. The colour of Fe²⁺ in aqueous solution is
A. green
B. blue
C. colourless
D. brown
Answer: A
19. Water hardness caused by Ca(HCO₃)₂ can be removed by
A. boiling
B. filtration
C. chlorination
D. adding lime
Answer: A
20. Which gas is responsible for the smell of rotten eggs?
A. CH₄
B. CO
C. H₂S
D. NH₃
Answer: C
21. Organic compounds that contain –OH group are
A. alkenes
B. alcohols
C. alkynes
D. esters
Answer: B
22. A homologous series has members with
A. different functional groups
B. same chemical properties
C. different general formula
D. same physical properties
Answer: B
23. The IUPAC name of CH₃–CH₂–CH₃ is
A. methane
B. ethane
C. propane
D. butane
Answer: C
24. An esterification reaction involves
A. acid + base
B. alcohol + acid
C. alkane + oxygen
D. salt + acid
Answer: B
25. A polymer is formed from small units called
A. isomers
B. allotropes
C. monomers
D. adducts
Answer: C
WAEC GCE 2026/2027 Chemistry 1 Objective/Essay Questions and Answers
26. The instrument used to measure atmospheric pressure is
A. manometer
B. thermometer
C. barometer
D. hygrometer
Answer: C
27. Which of the following gases is inert?
A. CO₂
B. Cl₂
C. He
D. NO₂
Answer: C
28. A reaction in which oxidation and reduction occur simultaneously is
A. combustion
B. redox
C. precipitation
D. polymerization
Answer: B
29. Which of the following is a transition element?
A. Sodium
B. Calcium
C. Zinc
D. Argon
Answer: C
30. An example of a weak acid is
A. HCl
B. H₂SO₄
C. HNO₃
D. CH₃COOH
Answer: D
31. The law that states that volume is inversely proportional to pressure is
A. Boyle’s law
B. Charles’ law
C. Graham’s law
D. Avogadro’s law
Answer: A
32. Which of the following is a greenhouse gas?
A. CO
B. CO₂
C. N₂
D. H₂
Answer: B
33. Which metal reacts vigorously with cold water?
A. Copper
B. Sodium
C. Iron
D. Silver
Answer: B
34. The chemical symbol for lead is
A. Pb
B. P
C. Pd
D. Pl
Answer: A
35. An electrolyte conducts electricity because it contains
A. molecules
B. atoms
C. ions
D. electrons only
Answer: C
36. The gas used in filling balloons is
A. oxygen
B. nitrogen
C. helium
D. carbon dioxide
Answer: C
37. The oxidation number of nitrogen in NH₃ is
A. +3
B. –3
C. +5
D. –1
Answer: B
38. Rusting of iron is a
A. reduction process
B. neutralization
C. redox process
D. condensation
Answer: C
39. The major constituent of natural gas is
A. methane
B. ethane
C. propane
D. butane
Answer: A
40. Which of the following is NOT a property of bases?
A. Turn red litmus blue
B. Have a bitter taste
C. Produce hydrogen with metals
D. Feel slippery
Answer: C
41. The colour of litmus in neutral solution is
A. red
B. blue
C. purple
D. pink
Answer: C
42. Hard water prevents soap from lathering because of
A. Ca²⁺ and Mg²⁺ ions
B. Na⁺ ions
C. K⁺ ions
D. Cl⁻ ions
Answer: A
43. The process of separating immiscible liquids is
A. distillation
B. solvent extraction
C. decantation
D. crystallization
Answer: C
44. An example of a noble gas is
A. Cl₂
B. Ne
C. CO₂
D. NO
Answer: B
WAEC GCE 2026 Chemistry 1 Objective/Essay Questions and Answers
45. The functional group in carboxylic acids is
A. –OH
B. –COOH
C. –NH₂
D. –CHO
Answer: B
46. Which gas is used in fire extinguishers?
A. Nitrogen
B. Carbon dioxide
C. Oxygen
D. Methane
Answer: B
47. The process of heating a substance strongly in absence of air is
A. roasting
B. calcination
C. cracking
D. distillation
Answer: B
48. Coal is an example of
A. renewable energy
B. fossil fuel
C. biofuel
D. inert material
Answer: B
49. The valency of oxygen is
A. 1
B. 2
C. 3
D. 4
Answer: B
50. The gas evolved when zinc reacts with acid is
A. oxygen
B. carbon dioxide
C. hydrogen
D. nitrogen
Answer: C
51. Chlorine water is used as a
A. fertilizer
B. disinfectant
C. nutrient
D. preservative
Answer: B
52. The major impurity in iron ore is
A. silica
B. phosphorus
C. nitrogen
D. sulphur
Answer: A
53. Which of the following is an amphoteric oxide?
A. MgO
B. CaO
C. ZnO
D. CO₂
Answer: C
54. The reaction between acid and metal produces
A. oxygen
B. hydrogen
C. nitrogen
D. methane
Answer: B
55. The number of moles in 11 g of CO₂ is (Molar mass = 44 g)
A. 0.25
B. 0.5
C. 1
D. 2
Answer: A
56. Which of the following is NOT a characteristic of metals?
A. Malleability
B. Ductility
C. Poor conductor of electricity
D. Lustre
Answer: C
57. The solubility of gases in water increases with
A. temperature
B. pressure
C. stirring
D. evaporation
Answer: B
58. Natural rubber is a polymer of
A. isoprene
B. ethene
C. propene
D. benzene
Answer: A
59. A substance that speeds up a reaction without being used up is a
A. catalyst
B. reactant
C. inhibitor
D. neutralizer
Answer: A
60. Which of the following is an alloy?
A. Sodium
B. Brass
C. Silicone
D. Mercury
Answer: B
CHEMISTRY 2 (ESSAY) – 10 QUESTIONS & ANSWERS
1. (a) Define isotopy.
(b) Chlorine exists as two isotopes: Cl-35 (75%) and Cl-37 (25%).
Calculate the relative atomic mass of chlorine.
Answer:
(a) Isotopy is the phenomenon where atoms of the same element have the same atomic number but different mass numbers due to different numbers of neutrons.
(b)
Relative atomic mass = (35 × 0.75) + (37 × 0.25)
= 26.25 + 9.25
= 35.5
2. (a) State Boyle’s Law.
(b) A gas occupies 250 cm³ at a pressure of 760 mmHg. Find its volume when the pressure becomes 950 mmHg (temperature constant).
Answer:
(a) Boyle’s Law states that the volume of a given mass of gas is inversely proportional to its pressure provided temperature is constant.
(b)
P₁V₁ = P₂V₂
760 × 250 = 950 × V₂
V₂ = (760 × 250) / 950
V₂ = 200 cm³
3. (a) Define oxidation and reduction.
(b) Identify the oxidizing and reducing agents in the reaction:
2Mg + O₂ → 2MgO
Answer:
(a)
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Oxidation is the addition of oxygen or loss of electrons.
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Reduction is the removal of oxygen or gain of electrons.
(b)
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Magnesium (Mg) is oxidized → reducing agent
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Oxygen (O₂) is reduced → oxidizing agent
4. (a) Write the electronic configuration of:
(i) Sodium (Na, Z = 11)
(ii) Sulphur (S, Z = 16)
(b) State whether each is a metal or non-metal.
Answer:
(a)
(i) Sodium: 2, 8, 1
(ii) Sulphur: 2, 8, 6
(b)
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Sodium → metal
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Sulphur → non-metal
5. (a) What is cracking of hydrocarbons?
(b) Distinguish between thermal cracking and catalytic cracking.
Answer:
(a) Cracking is the breaking down of large hydrocarbon molecules into smaller, more useful ones such as petrol, alkenes, and hydrogen.
(b)
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Thermal cracking: Uses very high temperature and pressure.
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Catalytic cracking: Uses lower temperature with a catalyst (e.g., zeolite), is more efficient.
6. (a) Explain the term hard water.
(b) State two methods of softening temporary hardness.
(c) Name one method for removing permanent hardness.
Answer:
(a) Hard water is water that does not readily form lather with soap due to dissolved Ca²⁺ and Mg²⁺ ions.
(b)
Temporary hardness can be removed by:
(i) Boiling
(ii) Adding slaked lime (Ca(OH)₂)
(c) Permanent hardness is removed by:
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Ion exchange / permutit method
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Adding washing soda (Na₂CO₃)
7. (a) List three properties of transition metals.
(b) Give two uses of iron.
Answer:
(a)
Transition metals:
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Form coloured compounds
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Have variable oxidation states
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Act as catalysts
(b) Uses of iron:
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Construction (bridges, buildings)
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Manufacture of machinery and vehicles
8. (a) What is meant by the mole of a substance?
(b) Calculate the number of moles in 15 g of CH₄
(Molar mass of CH₄ = 16 g/mol)
Answer:
(a) Mole is the amount of substance containing 6.02 × 10²³ particles (Avogadro’s number).
(b)
Moles = mass / molar mass
= 15 / 16
= 0.94 mol (approx.)
9. (a) Explain why diamond is hard while graphite is soft.
(b) State two uses of graphite.
Answer:
(a)
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Diamond: Each carbon atom forms four strong covalent bonds in a rigid 3-D structure → extremely hard.
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Graphite: Each carbon forms three bonds, leaving free electrons and weak forces between layers → soft and slippery.
(b)
Uses of graphite:
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As a lubricant
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In making electrodes
10. (a) Define electrolysis.
(b) Explain briefly what happens during the electrolysis of acidified water.
(c) State the products at the electrodes.
Answer:
(a) Electrolysis is the chemical decomposition of an electrolyte by passing an electric current through it.
(b)
Water dissociates into H⁺ and OH⁻ ions.
H⁺ ions migrate to the cathode (reduction).
OH⁻ ions migrate to the anode (oxidation).
(c)
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Cathode: Hydrogen gas (H₂)
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Anode: Oxygen gas (O₂)
