50 Objective Questions, 5 Theory Questions, and Full Answers
Introduction
Chemistry is one of the three compulsory core subjects for Science students in the WAEC 2026/2027 WASSCE. It is also a subject that many students find challenging because it sits between mathematics and biology, requiring you to calculate, memorize, and understand all at once. The good news is that WAEC Chemistry follows clear patterns, and students who prepare with past questions and a solid understanding of core concepts consistently score A grades.
The WAEC Chemistry syllabus covers Atomic Structure and Bonding, Separation Techniques, Acids and Bases, Electrochemistry, Rates of Reaction, Organic Chemistry, Environmental Chemistry, and the chemistry of metals and non-metals. Year after year, these areas produce the majority of both objective and theory questions.
50 Likely WAEC 2026/2027 WAEC 2026/2027 Chemistry Objective Questions
Each question includes four options. The correct answer is marked with ✅. Study the reasoning behind each correct choice, not just the answer itself.
Q1. Which of the following separation methods is used to separate a mixture of salt and water?
A. Filtration
B. Sublimation
C. Evaporation ✅
D. Decantation
Q2. The number of protons in an atom is called its:
A. Mass number
B. Atomic number ✅
C. Neutron number
D. Electron number
Q3. Which type of bond is formed between Na and Cl in NaCl?
A. Covalent bond
B. Metallic bond
C. Ionic bond ✅
D. Hydrogen bond
Q4. The pH of a neutral solution is:
A. 0
B. 7 ✅
C. 14
D. 1
Q5. Which of the following is a property of acids?
A. They turn red litmus paper blue
B. They have a pH above 7
C. They turn blue litmus paper red ✅
D. They produce hydroxide ions in solution
Q6. Rusting of iron requires:
A. Water only
B. Oxygen only
C. Both water and oxygen ✅
D. Carbon dioxide and water
Q7. Which of the following gases is produced when zinc reacts with dilute hydrochloric acid?
A. Oxygen
B. Hydrogen ✅
C. Chlorine
D. Carbon dioxide
Q8. Electrolysis of dilute sulphuric acid produces at the cathode:
A. Oxygen
B. Sulphur dioxide
C. Hydrogen ✅
D. Chlorine
Q9. The valency of aluminium is:
A. 1
B. 2
C. 3 ✅
D. 4
Q10. Which of the following is an example of a physical change?
A. Burning of wood
B. Rusting of iron
C. Melting of ice ✅
D. Decomposition of limestone
Q11. Avogadro’s number is approximately:
A. 6.02 × 10²¹
B. 6.02 × 10²³ ✅
C. 6.02 × 10²⁵
D. 6.02 × 10¹⁹
Q12. The molar mass of water (H₂O) is:
A. 16 g/mol
B. 18 g/mol ✅
C. 20 g/mol
D. 2 g/mol
Q13. Which of the following is the formula for glucose?
A. C₆H₁₂O₆ ✅
B. C₁₂H₂₂O₁₁
C. C₆H₆
D. CH₄
Q14. A catalyst increases the rate of a reaction by:
A. Providing additional heat to the reaction
B. Lowering the activation energy ✅
C. Increasing the concentration of reactants
D. Changing the products of the reaction
Q15. Which gas turns limewater milky?
A. Hydrogen
B. Oxygen
C. Carbon dioxide ✅
D. Nitrogen
Q16. The process of converting crude oil into useful fractions is called:
A. Distillation
B. Fractional distillation ✅
C. Cracking
D. Refining
Q17. Which of the following is NOT a hydrocarbon?
A. Methane
B. Ethanol ✅
C. Propane
D. Benzene
Q18. The hardness of water is caused by:
A. Dissolved sodium chloride
B. Dissolved calcium and magnesium salts ✅
C. Dissolved iron compounds
D. Dissolved oxygen
Q19. Electroplating is used to:
A. Separate metals from ores
B. Deposit a thin layer of metal on another metal using electrolysis ✅
C. Remove impurities from metals
D. Increase the melting point of metals
Q20. Which of the following is the correct formula for sulphuric acid?
A. HCl
B. HNO₃
C. H₂SO₄ ✅
D. H₃PO₄
Q21. When magnesium burns in air, the product is:
A. Magnesium hydroxide
B. Magnesium carbonate
C. Magnesium oxide ✅
D. Magnesium nitrate
Q22. The element with atomic number 6 is:
A. Oxygen
B. Nitrogen
C. Carbon ✅
D. Boron
Q23. Which of the following is a noble gas?
A. Nitrogen
B. Chlorine
C. Oxygen
D. Argon ✅
Q24. Alkanes are described as:
A. Unsaturated hydrocarbons
B. Saturated hydrocarbons ✅
C. Aromatic hydrocarbons
D. Hydrocarbon alcohols
Q25. The law of conservation of mass states that:
A. Mass can be created during a chemical reaction
B. Mass can be destroyed during a chemical reaction
C. The total mass of reactants equals the total mass of products ✅
D. Mass changes during a physical change
Q26. Which of these metals is the most reactive?
A. Iron
B. Copper
C. Silver
D. Potassium ✅
Q27. The test for the presence of starch is the addition of:
A. Benedict’s solution
B. Biuret reagent
C. Iodine solution ✅
D. Silver nitrate solution
Q28. A solution with a pH of 3 is:
A. Strongly alkaline
B. Weakly alkaline
C. Neutral
D. Acidic ✅
Q29. The process of obtaining a pure solid from a saturated solution by cooling is:
A. Filtration
B. Distillation
C. Crystallisation ✅
D. Chromatography
Q30. Which of the following is the formula for ethanol?
A. CH₄
B. C₂H₅OH ✅
C. C₂H₂
D. C₆H₆
Q31. The reaction of an acid with a base to produce salt and water only is called:
A. Oxidation
B. Decomposition
C. Neutralisation ✅
D. Combustion
Q32. Which of the following best describes an exothermic reaction?
A. A reaction that absorbs heat from the surroundings
B. A reaction that releases heat to the surroundings ✅
C. A reaction that has no energy change
D. A reaction that produces a gas
Q33. The oxidation state of oxygen in most compounds is:
A. +2
B. 0
C. -1
D. -2 ✅
Q34. Which process is used to remove permanent hardness from water?
A. Boiling
B. Adding washing soda (sodium carbonate) ✅
C. Filtration
D. Distillation is only option
Q35. Which of the following is an allotrope of carbon?
A. Iron
B. Graphite ✅
C. Silicon
D. Tin
Q36. The formula for calcium carbonate is:
A. CaCl₂
B. CaO
C. Ca(OH)₂
D. CaCO₃ ✅
Q37. Which of the following gases is produced during photosynthesis?
A. Carbon dioxide
B. Nitrogen
C. Hydrogen
D. Oxygen ✅
Q38. The bond between two hydrogen atoms in H₂ is:
A. Ionic
B. Metallic
C. Covalent ✅
D. Hydrogen bond
Q39. Soap is produced by the reaction of:
A. An acid with an ester
B. A fat or oil with a strong alkali ✅
C. An alcohol with an acid
D. A base with a salt
Q40. Which of the following is correct about isotopes?
A. They have different numbers of protons
B. They have the same number of neutrons
C. They have the same number of protons but different numbers of neutrons ✅
D. They are always radioactive
Q41. The process by which a gas changes directly to a solid without passing through the liquid state is:
A. Condensation
B. Sublimation ✅
C. Evaporation
D. Crystallisation
Q42. In a galvanic cell, oxidation occurs at the:
A. Cathode
B. Anode ✅
C. Salt bridge
D. Electrolyte
Q43. Which of the following is the correct equation for the combustion of methane?
A. CH₄ + O₂ → CO + H₂O
B. CH₄ + 2O₂ → CO₂ + 2H₂O ✅
C. CH₄ + O₂ → CO₂ + H₂
D. 2CH₄ + O₂ → 2CO + 4H₂
Q44. The empirical formula of a compound with 40% carbon, 6.7% hydrogen, and 53.3% oxygen is:
A. CH₂O ✅
B. C₂H₄O
C. CH₄O
D. C₂H₂O
Q45. Which of the following is a synthetic polymer?
A. Starch
B. Cellulose
C. Protein
D. Nylon ✅
Q46. Dilute nitric acid and copper react to produce:
A. Copper chloride and hydrogen
B. Copper sulphate and water
C. Copper nitrate, water, and nitrogen monoxide (NO) ✅
D. Copper oxide and hydrogen
Q47. The IUPAC name of CH₃CH₂CH₃ is:
A. Ethane
B. Propane ✅
C. Butane
D. Methane
Q48. Which of the following is used as an indicator to detect the end-point of a titration?
A. Benedict’s solution
B. Phenolphthalein ✅
C. Fehling’s solution
D. Tollens’ reagent
Q49. In the blast furnace, coke serves to:
A. Supply calcium carbonate
B. Remove silicon dioxide impurities
C. Supply carbon monoxide which reduces iron ore ✅
D. Increase the pH of the ore
Q50. The chemical formula of ammonia is:
A. NO₂
B. N₂O
C. NH₃ ✅
D. N₂H₂
5 Likely WAEC 2026/2027 WAEC 2026/2027 Chemistry Theory Questions with Model Answers
Theory questions require organized, well-explained answers. Use the model answers below as a guide for structure, depth, and language. Practise writing your own answers and comparing them to the models.
Theory Question 1
(a) What is meant by ‘mole’ in chemistry? (b) Calculate the number of moles in 44 g of carbon dioxide (CO₂). (Atomic masses: C = 12, O = 16) (c) How many molecules are present in this number of moles? (Avogadro’s number = 6.02 × 10²³)
MODEL ANSWER:
(a) THE MOLE:
The mole is the SI unit for amount of substance. It is defined as the amount of substance that contains as many elementary particles (atoms, molecules, ions, etc.) as there are atoms in exactly 12 grams of carbon-12. One mole of any substance contains 6.02 × 10²³ particles.
(b) NUMBER OF MOLES IN 44 g OF CO₂:
Molar mass of CO₂ = 12 + (2 × 16) = 12 + 32 = 44 g/mol
Number of moles = mass / molar mass = 44 / 44 = 1 mole ✓
(c) NUMBER OF MOLECULES:
Number of molecules = number of moles × Avogadro’s number
= 1 × 6.02 × 10²³
= 6.02 × 10²³ molecules ✓
Theory Question 2
(a) What is electrolysis? (b) Describe what happens at the anode and cathode when dilute hydrochloric acid (HCl) is electrolysed using inert electrodes. Write equations for the electrode reactions. (c) State TWO industrial uses of electrolysis.
MODEL ANSWER:
(a) ELECTROLYSIS:
Electrolysis is the process of using an electric current to bring about a chemical reaction in an electrolyte (a substance that conducts electricity in liquid or dissolved form). It decomposes the electrolyte at the electrodes.
(b) ELECTROLYSIS OF DILUTE HCl:
In dilute HCl, the ions present are H⁺, Cl⁻, and water molecules (providing OH⁻ and H⁺).
At the Cathode (negative electrode):
Hydrogen ions (H⁺) are attracted to the cathode and gain electrons (reduction):
2H⁺(aq) + 2e⁻ → H₂(g)
Hydrogen gas is produced and can be tested with a lit splint (squeaky pop). ✓
At the Anode (positive electrode):
In dilute HCl, hydroxide ions (OH⁻) from water are preferentially discharged:
4OH⁻(aq) → 2H₂O(l) + O₂(g) + 4e⁻
Oxygen gas is produced. (Note: In concentrated HCl, chloride ions would be discharged to give Cl₂) ✓
(c) TWO INDUSTRIAL USES OF ELECTROLYSIS:
1. Electroplating: Coating a cheaper metal (e.g., iron) with a precious or rust-resistant metal (e.g., chrome or gold) for protection or decoration.
2. Extraction of metals: Reactive metals like aluminium are extracted from their molten ores by electrolysis (since they cannot be reduced by carbon alone).
Theory Question 3
(a) Explain the term ‘rate of reaction’. (b) State FOUR factors that affect the rate of a chemical reaction. (c) Explain how temperature affects the rate of a chemical reaction at the molecular level.
MODEL ANSWER:
(a) RATE OF REACTION:
The rate of a chemical reaction is the speed at which reactants are converted into products. It can be measured by the increase in concentration of products per unit time or the decrease in concentration of reactants per unit time.
(b) FOUR FACTORS THAT AFFECT RATE OF REACTION:
1. Temperature: Increasing temperature increases the rate of reaction because particles move faster and collide more frequently and with greater energy.
2. Concentration: Increasing the concentration of reactants (in solution) increases the number of particles per unit volume, leading to more frequent collisions and a faster reaction.
3. Surface Area: Reducing particle size (increasing surface area) exposes more of the reactant to collisions, speeding up the reaction. Example: powdered chalk reacts faster with acid than a lump of chalk.
4. Catalysts: A catalyst provides an alternative reaction pathway with a lower activation energy, allowing more collisions to result in a successful reaction, increasing the rate without being consumed.
(c) EFFECT OF TEMPERATURE AT MOLECULAR LEVEL:
When temperature increases, the average kinetic energy of particles increases. This means particles move faster and collide more frequently. More importantly, a greater proportion of collisions occur with energy equal to or greater than the activation energy. The activation energy is the minimum energy needed for a collision to result in a chemical reaction. At higher temperatures, more collisions are successful, so the rate of reaction increases significantly.
Theory Question 4
(a) Define each of the following: (i) oxidation (ii) reduction. (b) Identify the substance oxidized and the substance reduced in the following reaction:CuO + H₂ → Cu + H₂O(c) State TWO differences between metallic and non-metallic oxides.
MODEL ANSWER:
(a) DEFINITIONS:
(i) Oxidation: In modern terms, oxidation is the loss of electrons by an atom, ion, or molecule. In older terms, oxidation is the addition of oxygen to a substance or the removal of hydrogen from it.
(ii) Reduction: Reduction is the gain of electrons by an atom, ion, or molecule. In older terms, reduction is the removal of oxygen from a substance or the addition of hydrogen to it.
(b) IN CuO + H₂ → Cu + H₂O:
Substance oxidized: Hydrogen (H₂)
Reason: H₂ gains oxygen to form H₂O. Hydrogen is oxidized (0 → +1 in H₂O). ✓
Substance reduced: Copper(II) oxide (CuO)
Reason: CuO loses oxygen to form Cu. Copper is reduced (Cu²⁺ → Cu⁰). ✓
This is a redox reaction. CuO acts as the oxidizing agent; H₂ acts as the reducing agent.
(c) TWO DIFFERENCES: METALLIC vs NON-METALLIC OXIDES
1. Metallic oxides are basic (react with acids to form salt and water). Non-metallic oxides are generally acidic (react with water to form acids, or react with bases to form salt and water). Example: Na₂O is basic; CO₂ is acidic.
2. Metallic oxides form ionic solids with high melting points. Non-metallic oxides are often gases or molecular solids with low melting points at room temperature.
Theory Question 5
(a) What is organic chemistry? (b) Write the structural formula for: (i) ethane (ii) ethene (iii) ethanol. (c) State ONE difference between alkanes and alkenes in terms of chemical reactivity, and give a test to distinguish between them.
MODEL ANSWER:
(a) ORGANIC CHEMISTRY:
Organic chemistry is the branch of chemistry that deals with compounds containing carbon, particularly those combined with hydrogen, and often with oxygen, nitrogen, sulphur, and other elements. Carbon compounds form the basis of all living things.
(b) STRUCTURAL FORMULAS:
(i) Ethane (C₂H₆):
H H
| |
H-C-C-H
| |
H H
(Single bonds only – saturated)
(ii) Ethene (C₂H₄):
H H
| |
C=C
| |
H H
(Contains a double bond – unsaturated)
(iii) Ethanol (C₂H₅OH):
H H
| |
H-C-C-O-H
| |
H H
(c) DIFFERENCE AND DISTINGUISHING TEST:
Alkanes undergo substitution reactions (e.g., with halogens in the presence of UV light). Alkenes undergo addition reactions (e.g., with bromine water).
TEST: Add bromine water (a yellow-orange solution) to each substance:
– Alkene: Decolourises the bromine water immediately (addition reaction occurs). ✓
– Alkane: No decolourisation (bromine water remains yellow-orange in the dark). ✓
This bromine water test is the standard test to distinguish between saturated and unsaturated hydrocarbons.
Study Tips: How to Score A in WAEC WAEC 2026/2027 Chemistry 2026/2027
Tip 1: Learn all separation techniques (filtration, distillation, crystallisation, sublimation, chromatography) and when each is used.
2: Know the reactivity series of metals. It appears in almost every WAEC Chemistry paper.
3: Practice balancing equations. A balanced equation shows you understand stoichiometry.
4: For organic chemistry, know the homologous series, their functional groups, general formulas, and typical reactions.
5: Learn common chemical tests: litmus test, lime water test, iodine test, and the tests for common gases (H₂, O₂, CO₂, Cl₂).
Frequently Asked Questions
Q: What are the most important topics in WAEC Chemistry 2026/2027?
A: Acids, bases and salts, electrolysis, rates of reaction and catalysis, organic chemistry (alkanes, alkenes, alcohols), mole calculations, separation techniques, and the periodic table are among the most consistently tested topics.
Q: How do I write a balanced chemical equation for WAEC?
A: Write the formulae of all reactants and products correctly first. Then balance by adjusting coefficients (the numbers in front of formulae) only. Never change subscripts within a formula. Check that the number of each atom is equal on both sides.
Q: Is the WAEC Chemistry practical exam compulsory?
A: Yes. WAEC Chemistry includes a practical examination (Paper 3) that tests your ability to perform and record laboratory procedures, particularly titration, qualitative analysis, and separation techniques. You must prepare for this paper separately with your school laboratory.
