WAEC chemistry past questions and answers for senior secondary school.
Chemistry is all about patterns, and WAEC has its favorite ones.
If you’ve been grinding formulas but still feel unsure, practicing past questions is the cheat code.
In this post you’ll get WAEC Chemistry past questions and answers with clear, step-by-step solutions for objective, theory, and practical. Study smart, spot the trends, and go into the exam knowing exactly what to expect. This will help you.
WAEC Chemistry Past Questions and Answers
1. Which of the following is a chemical property? A. Colour B. Density C. Flammability D. Mass. Answer: C
2. The relative atomic mass of an element is based on A. Carbon-14 B. Carbon-12 C. Hydrogen-1 D. Oxygen-16. Answer: B
3. Which of the following particles has no charge? A. Proton B. Electron C. Neutron D. Ion. Answer: C
4. The process of losing electrons is called A. Reduction B. Oxidation C. Neutralization D. Hydrolysis. Answer: B
5. Which of the following is an example of an alkali? A. NaCl B. NH₄Cl C. NaOH D. HCl. Answer: C
6. The gas that is most abundant in air is A. Oxygen B. Nitrogen C. Carbon dioxide D. Hydrogen. Answer: B
7. Which of the following is used as a bleaching agent? A. Chlorine B. Nitrogen C. Oxygen D. Hydrogen. Answer: A
8. The process of heating a solid to form vapour directly is A. Sublimation B. Evaporation C. Boiling D. Condensation. Answer: A
9. Which of the following is a covalent compound? A. NaCl B. H₂O C. KBr D. CaO. Answer: B
10. The pH of an alkaline solution is A. Less than 7 B. Equal to 7 C. Greater than 7 D. Zero. Answer: C
WAEC Chemistry Past Questions and Answers
11. Which of the following is an acid anhydride? A. CO₂ B. Na₂O C. CaO D. MgO. Answer: A
12. The element with atomic number 17 is A. Sodium B. Chlorine C. Oxygen D. Sulphur. Answer: B
13. Which of the following is used in making ammonia? A. Haber process B. Contact process C. Ostwald process D. Solvay process. Answer: A
14. The boiling point of pure water at standard pressure is A. 0°C B. 50°C C. 100°C D. 150°C. Answer: C
15. Which of the following is a physical change? A. Burning B. Rusting C. Melting D. Fermentation. Answer: C
16. The chemical formula of sodium hydroxide is A. NaOH B. NaCl C. Na₂O D. NaH. Answer: A
17. Which of the following is a non-electrolyte? A. NaCl B. HCl C. Sugar D. KOH. Answer: C
18. The number of protons in an atom equals its A. Mass number B. Atomic number C. Neutron number D. Electron shell. Answer: B
19. Which of the following is a greenhouse gas? A. O₂ B. N₂ C. CO₂ D. H₂. Answer: C
20. The process of separating dyes is called A. Filtration B. Chromatography C. Distillation D. Decantation. Answer: B
21. Which of the following is used to test for starch? A. Iodine B. Litmus C. Methyl orange D. Phenolphthalein. Answer: A
22. The colour of bromine water is A. Blue B. Brown C. Green D. Yellow. Answer: B
23. Which of the following is an alkane? A. C₂H₄ B. C₂H₂ C. C₂H₆ D. C₆H₆. Answer: C
24. The valency of aluminium is A. 1 B. 2 C. 3 D. 4. Answer: C
25. Which of the following is a base? A. HCl B. NH₃ C. CO₂ D. SO₂. Answer: B
26. The unit of molar volume is A. dm³/mol B. g/mol C. mol/dm³ D. J/mol. Answer: A
27. Which of the following is an oxidizing agent? A. H₂ B. CO C. O₂ D. CH₄. Answer: C
28. The gas used in respiration is A. CO₂ B. O₂ C. N₂ D. H₂. Answer: B
29. Which of the following is a salt? A. HCl B. NaOH C. NaCl D. NH₃. Answer: C
30. The process of rusting involves A. Only oxidation B. Only reduction C. Both oxidation and reduction D. No reaction. Answer: C
WAEC Chemistry Past Questions and Answers
31. Which of the following is an organic compound? A. CO₂ B. CH₄ C. NaCl D. H₂O. Answer: B
32. The formula of calcium oxide is A. CaO B. CaCl₂ C. CaCO₃ D. CaSO₄. Answer: A
33. Which of the following is used as fertilizer? A. NH₃ B. O₂ C. H₂ D. He. Answer: A
34. The process of neutralization produces A. Acid only B. Base only C. Salt and water D. Gas only. Answer: C
35. Which of the following is a transition metal? A. Na B. Ca C. Fe D. K. Answer: C
36. The colour change of litmus in base is A. Red to blue B. Blue to red C. Colourless D. Yellow. Answer: A
37. Which of the following is insoluble in water? A. NaCl B. Sugar C. Sand D. Alcohol. Answer: C
38. The process of distillation is used to A. Mix substances B. Separate liquids C. Heat solids D. Form compounds. Answer: B
39. Which of the following is a gas? A. NaCl B. H₂ C. Fe D. CaO. Answer: B
40. The atomic mass is the sum of A. Protons only B. Electrons only C. Protons and neutrons D. Neutrons only. Answer: C
41. Which of the following is a strong acid? A. CH₃COOH B. HCl C. NH₃ D. NaOH. Answer: B
42. The chemical formula of ammonia is A. NH₃ B. NH₂ C. N₂H₄ D. NH₄. Answer: A
43. Which of the following is used in making glass? A. Sand B. Sugar C. Oil D. Wood. Answer: A
44. The unit of pressure is A. Pascal B. Joule C. Watt D. Newton. Answer: A
45. Which of the following is a non-metal? A. Fe B. Cu C. S D. Zn. Answer: C
46. The oxidation number of hydrogen is usually A. -1 B. +1 C. 0 D. +2. Answer: B
47. Which of the following is a noble gas? A. He B. Cl C. Na D. Ca. Answer: A
48. The process of evaporation occurs at A. Surface B. Bottom C. Middle D. Everywhere equally. Answer: A
49. Which of the following is a mixture? A. Water B. Salt C. Air D. CO₂. Answer: C
50. The formula of sulphuric acid is A. H₂SO₄ B. HCl C. HNO₃ D. H₂CO₃. Answer: A
WAEC Chemistry Past Questions and Answers
51. Which of the following is used in electrolysis? A. Heat B. Electricity C. Light D. Pressure. Answer: B
52. The colour of methyl orange in base is A. Red B. Yellow C. Blue D. Green. Answer: B
53. Which of the following is an ester? A. CH₃COOH B. CH₃COOCH₃ C. CH₄ D. C₂H₆. Answer: B
54. The number of valence electrons in oxygen is A. 4 B. 5 C. 6 D. 7. Answer: C
55. Which of the following is a metal oxide? A. CO₂ B. SO₂ C. Na₂O D. NO₂. Answer: C
56. The process of crystallization is used for A. Heating B. Purification C. Mixing D. Cooling. Answer: B
57. Which of the following is used as fuel? A. O₂ B. H₂ C. N₂ D. He. Answer: B
58. The chemical symbol for potassium is A. K B. P C. Pt D. Po. Answer: A
59. Which of the following is a base? A. HCl B. NaOH C. CO₂ D. SO₂. Answer: B
60. The gas that turns limewater milky is A. O₂ B. H₂ C. CO₂ D. N₂. Answer: C
61. Which of the following is a catalyst? A. Fe in Haber process B. NaCl C. H₂O D. CO₂. Answer: A
62. The boiling point increases with A. Weak forces B. Strong forces C. No forces D. Random forces. Answer: B
63. Which of the following is an acid? A. NaOH B. HCl C. NH₃ D. CaO. Answer: B
64. The process of rust prevention using oil is called A. Lubrication B. Galvanization C. Painting D. Alloying. Answer: A
65. Which of the following is an ionic compound? A. CH₄ B. NaCl C. CO₂ D. NH₃. Answer: B
66. The unit of energy is A. Joule B. Watt C. Pascal D. Ampere. Answer: A
67. Which of the following is used in making soap? A. Acid B. Alkali C. Salt D. Gas. Answer: B
68. The process of adding oxygen is A. Reduction B. Oxidation C. Neutralization D. Sublimation. Answer: B
69. Which of the following is a hydrocarbon? A. CH₄ B. NaCl C. H₂O D. CO₂. Answer: A
70. The number of atoms in H₂O is A. 2 B. 3 C. 4 D. 5. Answer: B
WAEC Chemistry Past Questions and Answers
71. Which of the following is used as antiseptic? A. Ethanol B. Methane C. Benzene D. Propane. Answer: A
72. The pH of pure water is A. 1 B. 5 C. 7 D. 9. Answer: C
73. Which of the following is a weak base? A. NaOH B. NH₃ C. KOH D. Ca(OH)₂. Answer: B
74. The process of converting liquid to gas is A. Freezing B. Evaporation C. Condensation D. Sublimation. Answer: B
75. Which of the following is a halogen? A. Br B. Na C. Fe D. Ca. Answer: A
76. The molecular formula of methane is A. CH₄ B. C₂H₆ C. C₂H₄ D. C₃H₈. Answer: A
77. Which of the following is a reducing agent? A. O₂ B. H₂ C. Cl₂ D. NO₂. Answer: B
78. The colour of iodine is A. Yellow B. Violet C. Green D. Red. Answer: B
79. Which of the following is used in fermentation? A. Yeast B. Oxygen C. Nitrogen D. Hydrogen. Answer: A
80. The formula of nitric acid is A. HNO₃ B. HCl C. H₂SO₄ D. H₂CO₃. Answer: A
WAEC Chemistry Past Questions and Answers
81. Which of the following is an alkene? A. C₂H₆ B. C₂H₄ C. C₂H₂ D. CH₄. Answer: B
82. The valency of carbon is A. 2 B. 3 C. 4 D. 5. Answer: C
83. Which of the following is a polymer? A. Polyethene B. Methane C. Ethene D. Propane. Answer: A
84. The gas evolved in photosynthesis is A. CO₂ B. O₂ C. N₂ D. H₂. Answer: B
85. Which of the following is a salt? A. NaCl B. HCl C. NaOH D. NH₃. Answer: A
86. The process of dissolving is called A. Solvation B. Diffusion C. Dilution D. Reaction. Answer: A
87. Which of the following is an acid salt? A. NaHSO₄ B. NaCl C. Na₂CO₃ D. KCl. Answer: A
88. The element with symbol Fe is A. Iron B. Lead C. Zinc D. Copper. Answer: A
89. Which of the following is a base? A. H₂SO₄ B. NaOH C. CO₂ D. SO₂. Answer: B
90. The process of burning is called A. Combustion B. Reduction C. Neutralization D. Electrolysis. Answer: A
91. Which of the following is a gas? A. Br₂ B. Hg C. O₂ D. I₂. Answer: C
92. The colour of chlorine gas is A. Greenish-yellow B. Blue C. Red D. Black. Answer: A
93. Which of the following is used in making fertilizers? A. NH₃ B. He C. Ne D. Ar. Answer: A
94. The process of cooling gas to liquid is A. Condensation B. Evaporation C. Sublimation D. Freezing. Answer: A
95. Which of the following is a non-metal? A. Cu B. Fe C. S D. Zn. Answer: C
96. The unit of temperature is A. Kelvin B. Meter C. Second D. Ampere. Answer: A
97. Which of the following is a strong base? A. NH₃ B. NaOH C. H₂O D. CO₂. Answer: B
98. The chemical formula of calcium carbonate is A. CaCO₃ B. CaO C. CaCl₂ D. CaSO₄. Answer: A
99. Which of the following is an oxidizing agent? A. H₂ B. CO C. O₂ D. CH₄. Answer: C
WAEC Chemistry Past Questions and Answers (Theory section)
100. The process of removing impurities from water is A. Purification B. Mixing C. Heating D. Cooling. Answer: A
101. Explain the term atom and list its subatomic particles.
An atom is the smallest unit of an element that retains its chemical properties. It consists of protons, neutrons, and electrons.
102. Define an acid and state two of its properties.
An acid is a substance that produces hydrogen ions in solution. It turns blue litmus red and reacts with metals to produce hydrogen gas.
103. What is a base? Give two examples.
A base is a substance that neutralizes acids to form salt and water. Examples are sodium hydroxide and ammonia.
104. Explain the difference between a mixture and a compound.
A mixture is a physical combination of substances that can be separated easily, while a compound is formed chemically and cannot be separated by physical means.
105. Describe evaporation.
Evaporation is the process by which a liquid changes into vapour at its surface below its boiling point.
106. Define oxidation and give one example.
Oxidation is the gain of oxygen or loss of electrons. An example is rusting of iron.
107. What is reduction?
Reduction is the loss of oxygen or gain of electrons in a reaction.
108. Define solubility.
Solubility is the maximum amount of solute that can dissolve in a solvent at a given temperature.
109. Explain neutralization with an example.
Neutralization is the reaction between an acid and a base to form salt and water. Example: HCl + NaOH → NaCl + H₂O.
110. What is a catalyst? Give one example.
A catalyst is a substance that speeds up a chemical reaction without being consumed. Example: Iron in the Haber process.
111. Define electrolysis.
Electrolysis is the chemical decomposition of a substance using electricity.
112. What is a mole?
A mole is the amount of substance containing Avogadro’s number of particles.
113. Explain the term valency.
Valency is the combining power of an element, indicating how many bonds it can form.
114. What is an element?
An element is a pure substance made up of only one type of atom.
115. Define compound and give an example.
A compound is a substance formed from two or more elements chemically combined. Example: Water.
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