Original WAEC Chemistry Past Questions And Answers (Updated To 2024)

Preparing effectively for the WAEC Chemistry exam is key to success, and one of the most efficient ways to prepare is by using original past questions and answers—specifically those updated to 2024. These resources give you a clear insight into the exam format, the types of questions asked, and the important topics emphasized over time.

Why Practice with Original WAEC Chemistry Past Questions?

Original WAEC Chemistry past questions provide several advantages:

Authentic Exam Experience: You get to practice questions almost identical to what appears in the actual exam.
Topic Familiarity: They highlight the frequently recurring areas like Organic Chemistry, Atomic Structure, Chemical Reactions, and more.
Time Management Skills: By practicing with real past questions, you learn how to allocate exam time efficiently.
Error Identification: Reviewing your attempts against provided answers helps you pinpoint and correct mistakes.

Structure of the WAEC Chemistry Examination

The Chemistry exam typically involves three papers:

Paper 1: Objective multiple-choice questions (multiple options per question).
Paper 2: Theory questions, including structured and essay questions focusing on explanation, equations, calculations, and experimental skills.
Paper 3: Practical or alternative to practical paper involving experiments, observations, and data interpretation.

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Each paper tests various facets of chemistry knowledge, from theory to application.

Key Topics Based on 2024 WAEC Chemistry Past Questions

The updated 2024 past questions emphasize core topics, such as:

Atomic structure and periodic table
Chemical bonding and molecular structure
Stoichiometry and chemical calculations
States of matter and gas laws
Acids, bases, and salts
Organic chemistry including hydrocarbons, alcohols, and polymers
Electrochemistry and oxidation-reduction reactions
Environmental chemistry
Laboratory practical skills and data analysis

Benefits of Using 2024 Updated Chemistry Past Questions and Answers

Relevance: They reflect the latest syllabus and exam trend adjustments.
Answer Explanations: Step-by-step solutions help deepen understanding.
Confidence Boost: Regular practice reduces exam anxiety.
Convenient Access: Many educational platforms offer free or low-cost downloadable resources.

WAEC Chemistry Past Questions and Answers

Which of the following metals is common to both brass and bronze?
(a) Aluminium
(b) Copper
(c) Lead
(d) Iron
Answer: (b) Copper
The alkanol obtained from the production of soap is:
(a) Dihydric alkanol
(b) Tertiary alkanol
(c) Trihydric alkanol
(d) Monohydric alkanol
Answer: (d) Monohydric alkanol
When an alkene is formed by heating a compound X with concentrated tetraoxosulphate(VI) acid, X is likely:
(a) Alkane
(b) Alkanol
(c) Alkanoate
(d) Alkyne
Answer: (b) Alkanol
Ripening of fruits is hastened by using:
(a) Ethanol
(b) Ethane
(c) Ethene
(d) Ethyne
Answer: (c) Ethene
Which of the following compounds is a secondary alkanol?
(i) CH3CH(CH3)CH2OH
(ii) CH3CH2CH(OH)CH3
(iii) CH3C(OH)(CH3)CH3
(a) (i) only
(b) (ii) only
(c) (i) and (iii) only
(d) (ii) and (iii) only
Answer: (b) (ii) only
Considering the reaction: C2H4 + 3O2 → 2CO2 + 2H2O, the volume of oxygen at STP required to burn 14 g of ethene (C2H4) is:
(a) 64.2 dm³
(b) 33.6 dm³
(c) 11.2 dm³
(d) 3.73 dm³
Answer: (b) 33.6 dm³
Which of the following is a non-electrolyte?
(a) H2SO4
(b) CH3COOH
(c) C6H12O6
(d) NH4Cl
Answer: (c) C6H12O6 (glucose)
The oxidation number of sulfur in H2SO3 is:
(a) +4
(b) +6
(c) +2
(d) +3
Answer: (a) +4
A compound with empirical formula CH2O and molecular mass 90 has the molecular formula:
(a) C4H10O2
(b) C3H6O3
(c) C3H10O2
(d) C2H2O4
Answer: (b) C3H6O3
The process of converting starch to glucose is:
(a) Condensation
(b) Dehydration
(c) Fermentation
(d) Hydrolysis
Answer: (d) Hydrolysis
Which of the following is used to hasten the ripening of fruits?
(a) Ethanol
(b) Ethane
(c) Ethene
(d) Ethyne
Answer: (c) Ethene
Separation technique suitable for separating iodine from tetrachloromethane is:
(a) Filtration
(b) Solvent extraction
(c) Fractional distillation
(d) Decantation
Answer: (b) Solvent extraction
Dilute trioxonitrate (V) acid does not produce hydrogen when it reacts with metals because it is a:
(a) Strong oxidizing agent
(b) Neutralizing agent
(c) Weak acid
(d) Nonreactive acid
Answer: (a) Strong oxidizing agent
The molar mass of calcium sulfate (CaSO4) is approximately:
(a) 136
(b) 120
(c) 138
(d) 133
Answer: (c) 136
Which of the following exhibits a dipole moment?
(a) CO2
(b) CH4
(c) H2O
(d) Cl2
Answer: (c) H2O
Zinc dust reacts with copper(II) sulfate solution to give:
(a) Copper metal and zinc sulfate
(b) Zinc metal and copper sulfate
(c) Zinc metal and zinc sulfate
(d) Copper and copper sulfate
Answer: (a) Copper metal and zinc sulfate
The process of separating two liquids with close boiling points is called:
(a) Simple distillation
(b) Fractional distillation
(c) Filtration
(d) Crystallization
Answer: (b) Fractional distillation
The concentration of a solution is the:
(a) Mass of solute per unit volume of solvent
(b) Mass of solute per volume of solution
(c) Volume of solute per volume of solution
(d) Volume of solute per unit mass of solvent
Answer: (b) Mass of solute per volume of solution
The strongest intermolecular force exists in:
(a) Ionic compounds
(b) Covalent compounds
(c) Metallic compounds
(d) Hydrogen-bonded compounds
Answer: (a) Ionic compounds
Which element has the highest electronegativity?
(a) Hydrogen
(b) Fluorine
(c) Oxygen
(d) Nitrogen
Answer: (b) Fluorine
Dilute trioxonitrate (V) acid does not produce hydrogen when it reacts with metals because:
(a) It is a strong oxidizing agent
(b) It reacts with the product
(c) There is no visible reaction
(d) It is highly corrosive
Answer: (a) It is a strong oxidizing agent
How many moles are there in 3.0 g of oxygen? (O = 16)
(a) 0.0093
(b) 0.0930
(c) 0.6250
(d) 0.0625
Answer: (d) 0.0625
A mixture containing two salts of different solubility can be separated by:
(a) Chromatography
(b) Distillation
(c) Crystallization
(d) Evaporation
Answer: (c) Crystallization
The separation technique suitable for separating iodine from tetrachloromethane is:
(a) Solvent extraction
(b) Fractional distillation
(c) Decantation
(d) Filtration
Answer: (a) Solvent extraction
Which of the following laws or theory cannot be explained by the application of the kinetic theory of gases?
(a) Dalton’s atomic theory
(b) Charles’ law
(c) Gay-Lussac’s law
(d) Boyle’s law
Answer: (a) Dalton’s atomic theory
The primary component of natural gas is:
(a) Butane
(b) Ethane
(c) Methane
(d) Propane
Answer: (c) Methane
Thermal cracking of alkanes usually:
(a) Involves decomposition
(b) Is an exothermic process
(c) Produces only small alkanes
(d) Requires hydrogen
Answer: (a) Involves decomposition
What takes place at the cathode during electrolysis?
(a) Anions lose electrons
(b) Anions are oxidized
(c) Cations are discharged
(d) Cations are oxidized
Answer: (c) Cations are discharged
How many grams of sodium hydroxide (NaOH) would be needed to produce a given amount? (NaOH = 40.0)
(a) 0.02 g
(b) 0.80 g
(c) 20.0 g
(d) 800.0 g
Answer: (b) 0.80 g
The formation of a bond between hydrogen and a highly electronegative atom results in:
(a) Polarity
(b) Dipole
(c) Metallic bond
(d) Electrovalent bond
Answer: (a) Polarity
Which of the following is a secondary alkanol?
(i) CH3CH(CH3)CH2OH
(ii) CH3CH2CH(OH)CH3
(iii) CH3C(OH)(CH3)CH3
(a) (i) only
(b) (ii) only
(c) (i) and (iii) only
(d) (ii) and (iii) only
Answer: (b) (ii) only
The molar mass of calcium sulfate (CaSO4) is approximately:
(a) 136
(b) 120
(c) 138
(d) 133
Answer: (a) 136
Which of the following is a non-electrolyte?
(a) H2SO4
(b) CH3COOH
(c) C6H12O6
(d) NH4Cl
Answer: (c) C6H12O6
The oxidation number of sulfur in H2SO3 is:
(a) +4
(b) +6
(c) +2
(d) +3
Answer: (a) +4
A compound with empirical formula CH2O and molecular mass 90 has the molecular formula:
(a) C4H10O2
(b) C3H6O3
(c) C3H10O2
(d) C2H2O4
Answer: (b) C3H6O3
The process of converting starch to glucose is:
(a) Condensation
(b) Dehydration
(c) Fermentation
(d) Hydrolysis
Answer: (d) Hydrolysis
The alkanol obtained from the production of soap is:
(a) Dihydric alkanol
(b) Tertiary alkanol
(c) Trihydric alkanol
(d) Monohydric alkanol
Answer: (d) Monohydric alkanol
Ripening of fruits is hastened by using:
(a) Ethanol
(b) Ethane
(c) Ethene
(d) Ethyne
Answer: (c) Ethene
A gas that is both a good oxidizing agent and strong acid is:
(a) CO2
(b) SO2
(c) Cl2
(d) SO3
Answer: (d) SO3
Which of these compounds is an ester?
(a) Ethanol
(b) Ethanoic acid
(c) Methanol
(d) Ethyl ethanoate
Answer: (d) Ethyl ethanoate
The reaction that involves loss of electrons is called:
(a) Oxidation
(b) Reduction
(c) Neutralization
(d) Dissociation
Answer: (a) Oxidation
The pH of a neutral solution at 25°C is:
(a) 0
(b) 7
(c) 14
(d) 1
Answer: (b) 7
Which substance cannot be obtained from the fractional distillation of petroleum?
(a) Gasoline
(b) Diesel
(c) Methanol
(d) Kerosene
Answer: (c) Methanol
The electron configuration of chlorine (atomic number 17) is:
(a) 2,8,7
(b) 2,8,8
(c) 2,7,8
(d) 2,8,9
Answer: (a) 2,8,7
Electrolysis is used to:
(a) Break down compounds
(b) Combine elements
(c) Measure conductivity
(d) None of the above
Answer: (a) Break down compounds
The metal that reacts vigorously with cold water is:
(a) Sodium
(b) Iron
(c) Copper
(d) Zinc
Answer: (a) Sodium
The reaction of an acid and a carbonate produces:
(a) Salt, water and carbon dioxide
(b) Salt and water only
(c) Salt and hydrogen
(d) Salt and oxygen
Answer: (a) Salt, water and carbon dioxide
The first ionization energy is:
(a) The energy to remove an electron from a neutral atom
(b) The energy to remove a neutron
(c) The energy to add an electron
(d) None of these
Answer: (a) The energy to remove an electron from a neutral atom
A saturated hydrocarbon contains only:
(a) Single bonds
(b) Double bonds
(c) Triple bonds
(d) Both double and triple bonds
Answer: (a) Single bonds
The mass of one mole of carbon atoms is:
(a) 6 g
(b) 12 g
(c) 24 g
(d) 18 g
Answer: (b) 12 g
Which of the following is an example of an alkene?
(a) Ethane
(b) Ethene
(c) Ethyne
(d) Methane
Answer: (b) Ethene
Which of the following pairs of elements will have the greatest electronegativity difference?
(a) Na and Cl
(b) C and H
(c) N and O
(d) S and Se
Answer: (a) Na and Cl
The main component of natural gas is:
(a) Ethane
(b) Propane
(c) Methane
(d) Butane
Answer: (c) Methane
The process of converting ethanol to ethene is an example of:
(a) Addition
(b) Substitution
(c) Elimination
(d) Oxidation
Answer: (c) Elimination
An acid that only partially ionizes in solution is called:
(a) Strong acid
(b) Weak acid
(c) Neutral acid
(d) Alkali
Answer: (b) Weak acid
The functional group of alcohols is:
(a) –COOH
(b) –OH
(c) –NH2
(d) –CHO
Answer: (b) –OH
The process of adding hydrogen to unsaturated hydrocarbons is known as:
(a) Hydrogenation
(b) Hydration
(c) Halogenation
(d) Substitution
Answer: (a) Hydrogenation
The molar mass of oxygen gas (O2) is:
(a) 16 g/mol
(b) 32 g/mol
(c) 8 g/mol
(d) 48 g/mol
Answer: (b) 32 g/mol
The substance formed when an acid reacts with a base is:
(a) Salt and water
(b) Gas
(c) Heat only
(d) Water only
Answer: (a) Salt and water
The simplest form of any compound expressing the ratio of elements present is the:
(a) Molecular formula
(b) Structural formula
(c) Empirical formula
(d) Chemical formula
Answer: (c) Empirical formula
An example of a primary alkanol is:
(a) Methanol
(b) Propan-2-ol
(c) Butan-2-ol
(d) Ethanoic acid
Answer: (a) Methanol
A mixture of butanoic acid and ethanol warmed in the presence of concentrated sulfuric acid gives off a fragrant odour due to formation of:
(a) Ester
(b) Alcohol
(c) Ether
(d) Ketone
Answer: (a) Ester
The valency of nitrogen in NH3 is:
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (c) 3
An acid with pH 2 is:
(a) Neutral
(b) Weakly acidic
(c) Strongly acidic
(d) Basic
Answer: (c) Strongly acidic
Atomic number is the number of:
(a) Protons only
(b) Neutrons only
(c) Electrons only
(d) Protons plus neutrons
Answer: (a) Protons only
An increase in temperature generally causes the solubility of solids in liquids to:
(a) Increase
(b) Decrease
(c) Remain constant
(d) Become zero
Answer: (a) Increase
The molar volume of a gas at standard temperature and pressure (STP) is approximately:
(a) 24 dm³
(b) 22.4 dm³
(c) 10 dm³
(d) 1 dm³
Answer: (b) 22.4 dm³
The reaction between an acid and a metal produces:
(a) Salt and water
(b) Salt and hydrogen gas
(c) Salt and carbon dioxide
(d) Water only
Answer: (b) Salt and hydrogen gas
In the reaction NaOH + HCl → NaCl + H2O, HCl is:
(a) Base
(b) Acid
(c) Salt
(d) Oxide
Answer: (b) Acid
The greenhouse gas contributing most to global warming is:
(a) Nitrogen
(b) Oxygen
(c) Carbon dioxide
(d) Argon
Answer: (c) Carbon dioxide
The molecular formula of propane is:
(a) C2H6
(b) C3H8
(c) C4H10
(d) C3H6
Answer: (b) C3H8
When hydrogen gas is burned in air, the major product formed is:
(a) Water
(b) Carbon dioxide
(c) Carbon monoxide
(d) Oxygen
Answer: (a) Water
The process used to separate two immiscible liquids is:
(a) Filtration
(b) Distillation
(c) Decantation
(d) Chromatography
Answer: (c) Decantation
Which of the following is a halogen?
(a) Sodium
(b) Chlorine
(c) Argon
(d) Oxygen
Answer: (b) Chlorine
Which of the following is an ionic compound?
(a) CO2
(b) NaCl
(c) CH4
(d) H2O
Answer: (b) NaCl
The pH of a solution with a hydrogen ion concentration of $1 0^{-4}$ mol/dm³ is:
(a) 4
(b) 7
(c) 10
(d) 14
Answer: (a) 4
The oxidation state of oxygen in most compounds is:
(a) +2
(b) -2
(c) 0
(d) +1
Answer: (b) -2
The atomic number of an element corresponds to the number of:
(a) Protons in the nucleus
(b) Neutrons in the nucleus
(c) Electrons in the outer shell
(d) Electrons in the inner shell
Answer: (a) Protons in the nucleus
The gas with a sharp odor used in the laboratory as a disinfectant is:
(a) Oxygen
(b) Chlorine
(c) Nitrogen
(d) Hydrogen
Answer: (b) Chlorine
The term ‘solubility’ refers to:
(a) Ability of a solute to dissolve in a solvent
(b) Density of the solution
(c) Concentration of a solution
(d) Purity of a substance
Answer: (a) Ability of a solute to dissolve in a solvent
The functional group –COOH is found in:
(a) Alcohols
(b) Aldehydes
(c) Carboxylic acids
(d) Ketones
Answer: (c) Carboxylic acids
The percentage composition of water in hydrated copper (II) sulfate (CuSO4·5H2O) is approximately:
(a) 25%
(b) 36%
(c) 50%
(d) 64%
Answer: (b) 36%
Which of these statements accurately describes an exothermic reaction?
(a) Absorbs heat from surroundings
(b) Releases heat to surroundings
(c) Is independent of temperature
(d) Involves gases only
Answer: (b) Releases heat to surroundings
The electron configuration of sodium (Na) is:
(a) 2, 8, 1
(b) 2, 7, 2
(c) 1, 8, 2
(d) 2, 8, 2
Answer: (a) 2, 8, 1
The correct formula of calcium phosphate is:
(a) Ca3(PO4)2
(b) Ca2PO4
(c) CaPO4
(d) Ca3PO4
Answer: (a) Ca3(PO4)2
The process of converting a liquid to gas at a temperature below boiling point is:
(a) Boiling
(b) Melting
(c) Evaporation
(d) Condensation
Answer: (c) Evaporation
The relative molecular mass of methane (CH4) is:
(a) 12
(b) 16
(c) 14
(d) 18
Answer: (b) 16
Which of the following elements participates in hydrogen bonding?
(a) Carbon
(b) Nitrogen
(c) Sulfur
(d) Sodium
Answer: (b) Nitrogen
The major product of the combustion of any hydrocarbon is:
(a) Moisture and CO2
(b) CO
(c) H2O
(d) SO2
Answer: (a) Moisture and CO2
How many moles of hydrogen gas are required to completely react with 1 mole of oxygen gas to form water?
(a) 1 mole
(b) 2 moles
(c) 3 moles
(d) 4 moles
Answer: (b) 2 moles
The allotropes of carbon include:
(a) Diamond and graphite
(b) Graphite and coke
(c) Coal and diamond
(d) Graphite and coal
Answer: (a) Diamond and graphite
The common oxidation state of group 1 elements in compounds is:
(a) +1
(b) +2
(c) 0
(d) -1
Answer: (a) +1
The commercial preparation of hydrogen gas involves:
(a) Electrolysis of water
(b) Reaction of acid with metal
(c) Decomposition of water vapour at high temperature
(d) All of the above
Answer: (d) All of the above
The IUPAC name of CH3CH2OH is:
(a) Methanol
(b) Ethanol
(c) Ethanoic acid
(d) Propanol
Answer: (b) Ethanol
Which of the following is amphoteric?
(a) NaOH
(b) Al(OH)3
(c) HCl
(d) NH3
Answer: (b) Al(OH)3
The compact crystalline form is characteristic of:
(a) Liquids
(b) Gases
(c) Solids
(d) Plasmas
Answer: (c) Solids
The number of moles in 18 g of water (H2O) is:
(a) 0.5 mol
(b) 1 mol
(c) 2 mol
(d) 3 mol
Answer: (b) 1 mol
The shape of the methane molecule (CH4) is:
(a) Tetrahedral
(b) Linear
(c) Bent
(d) Trigonal pyramidal
Answer: (a) Tetrahedral
The catalyst used in the manufacture of ammonia by the Haber process is:
(a) Nickel
(b) Platinum
(c) Iron
(d) Copper
Answer: (c) Iron
The correct symbol for the element with electronic configuration 2, 8, 7 is:
(a) O
(b) N
(c) Cl
(d) F
Answer: (c) Cl
Which of the following best defines an isotope?
(a) Atoms of the same element with different numbers of protons
(b) Atoms with same atomic number but different mass numbers
(c) Atoms with different elements having the same mass number
(d) Atoms with the same mass number and number of neutrons
Answer: (b) Atoms with same atomic number but different mass numbers
The molecular formula of ethylene is:
(a) C2H4
(b) C2H6
(c) C3H6
(d) C3H8
Answer: (a) C2H4
The pH of an aqueous solution with [OH–] = $1 0^{-5}$ mol/L is:
(a) 5
(b) 7
(c) 9
(d) 10
Answer: (c) 9
The process in which compounds are broken down by heat in absence of air is:
(a) Cracking
(b) Combustion
(c) Polymerization
(d) Neutralization
Answer: (a) Cracking
The anode in an electrolytic cell is where:
(a) Reduction occurs
(b) Oxidation occurs
(c) Electrons enter the cell
(d) None of the above
Answer: (b) Oxidation occurs
Which of the following is a primary alcohol?
(a) Propanol-2
(b) Propanol-1
(c) Propanone
(d) Propene
Answer: (b) Propanol-1
Which element is the most reactive among the halogens?
(a) Iodine
(b) Chlorine
(c) Fluorine
(d) Bromine
Answer: (c) Fluorine
What is the major gas evolved when dilute hydrochloric acid reacts with zinc granules?
(a) Oxygen
(b) Hydrogen
(c) Nitrogen
(d) Carbon dioxide
Answer: (b) Hydrogen
The empirical formula of a compound with molecular formula C4H10 is:
(a) CH5
(b) C2H5
(c) C4H10
(d) CH2.5
Answer: (b) C2H5
The process in which saturated compounds are converted to unsaturated compounds releasing hydrogen gas is called:
(a) Hydrogenation
(b) Dehydration
(c) Cracking
(d) Dehydrogenation
Answer: (d) Dehydrogenation
A homologous series is a group of compounds with:
(a) Different general formula but same functional group
(b) Similar physical properties and gradual change in chemical properties
(c) Same physical properties only
(d) Same chemical properties only
Answer: (b) Similar physical properties and gradual change in chemical properties
The main component of natural gas is:
(a) Ethane
(b) Methane
(c) Propane
(d) Butane
Answer: (b) Methane
The maximum number of electrons that can occupy the first energy level is:
(a) 1
(b) 2
(c) 8
(d) 18
Answer: (b) 2
Which of the following compounds is an aldehyde?
(a) CH3CHO
(b) CH3COOH
(c) CH3OH
(d) CH3CH2OH
Answer: (a) CH3CHO
The molar volume of any gas at standard temperature and pressure (STP) is:
(a) 22.4 L
(b) 24.0 L
(c) 20.1 L
(d) 25.5 L
Answer: (a) 22.4 L
Oxidation in terms of electron transfer is:
(a) Loss of electrons
(b) Gain of electrons
(c) Loss of protons
(d) Gain of protons
Answer: (a) Loss of electrons
Combustion of carbon in insufficient oxygen gives:
(a) Carbon dioxide
(b) Carbon monoxide
(c) Carbonic acid
(d) Carbonates
Answer: (b) Carbon monoxide
Which method is used to obtain pure dry crystals from a solution?
(a) Filtration
(b) Crystallization
(c) Distillation
(d) Sublimation
Answer: (b) Crystallization
When an atom gains electrons, it becomes:
(a) Cation
(b) Anion
(c) Neutral
(d) Isotope
Answer: (b) Anion
Atomic number of an element gives the number of:
(a) Neutrons
(b) Protons
(c) Electrons in the outer shell
(d) Total electrons
Answer: (b) Protons

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Original WAEC Chemistry Past Questions and Answers (Updated to 2024)