Sample WAEC-style Practice Questions (Original Content)
WAEC Style
Question 1
Which of the following is a constituent of a mixture but not a compound?
A. Fixed composition by mass
B. Chemical bonds between particles
C. Components can be separated by physical means
D. New substances are formed
Answer: C. Components can be separated by physical means
Explanation: Mixtures are physical combinations and can be separated by methods like filtration or distillation, unlike compounds which require chemical methods.
Question 2
The electronic configuration of an atom is 2, 8, 7. How many valence electrons does it have?
A. 2
B. 8
C. 7
D. 17
Answer: C. 7
Explanation: Valence electrons are the electrons in the outermost shell.
Question 3
Which of the following elements belongs to the same group as Magnesium (Atomic number 12)?
A. Sodium (11)
B. Calcium (20)
C. Aluminum (13)
D. Potassium (19)
Answer: B. Calcium (20)
Explanation: Both Magnesium (2, 8, 2) and Calcium (2, 8, 8, 2) have 2 valence electrons and belong to Group 2.
Question 4
The type of bond formed between two atoms of Hydrogen to form H2 is:
A. Ionic bond
B. Covalent bond
C. Metallic bond
D. Coordinate bond
Answer: B. Covalent bond
Explanation: Two non-metal atoms of the same element share electrons to form a covalent bond.
Question 5
According to Dalton's atomic theory, atoms are:
A. Indivisible and indestructible
B. Made of protons and neutrons
C. Large heavy particles
D. Mostly empty space
Answer: A. Indivisible and indestructible
Explanation: While later proven wrong by the discovery of subatomic particles, this was a primary postulate of Dalton's theory.
Question 6
The state of matter with a fixed volume but no fixed shape is:
A. Solid
B. Liquid
C. Gas
D. Plasma
Answer: B. Liquid
Explanation: Liquids take the shape of their container but maintain a constant volume.
If the pressure of a gas is doubled at constant temperature, the volume will be:
A. Doubled
B. Halved
C. Quadrupled
D. Unchanged
Answer: B. Halved
Explanation: According to Boyle's Law, volume is inversely proportional to pressure.
Question 9
Which of the following is an example of a physical property?
A. Flammability
B. Reactivity with acid
C. Boiling point
D. Ability to rust
Answer: C. Boiling point
Explanation: Boiling point is observed without changing the substance into a new chemical.
Question 10
The formula for Carbon (II) oxide is:
A. CO2
B. C2O
C. CO
D. C2O2
Answer: C. CO
Explanation: Carbon (II) oxide is commonly known as carbon monoxide.
Question 11
An acid that ionizes completely in water is described as a:
A. Weak acid
B. Strong acid
C. Concentrated acid
D. Dilute acid
Answer: B. Strong acid
Explanation: Strong acids like HCl or H2SO4 dissociate fully into ions in aqueous solutions.
Question 12
The IUPAC name of CH3CH2OH is:
A. Methanol
B. Ethanol
C. Propanol
D. Ethanoic acid
Answer: B. Ethanol
Explanation: Two carbons (eth-) and an alcohol group (-ol).
Question 13
Which of the following gases is used in the manufacture of ammonia?
A. Oxygen
B. Nitrogen
C. Chlorine
D. Argon
Answer: B. Nitrogen
Explanation: Ammonia (NH3) is made from Nitrogen and Hydrogen via the Haber process.
Question 14
What is the oxidation number of Oxygen in most of its compounds?
A. -1
B. -2
C. +2
D. 0
Answer: B. -2
Explanation: Oxygen usually accepts two electrons to reach a stable state.
Question 15
The indicator methyl orange turns ______ in acidic solutions.
A. Yellow
B. Blue
C. Red/Pink
D. Colorless
Answer: C. Red/Pink
Explanation: Methyl orange is red in acid and yellow in bases.
Question 16
Which of the following subatomic particles has no charge?
A. Proton
B. Electron
C. Neutron
D. Alpha particle
Answer: C. Neutron
Explanation: Neutrons are electrically neutral.
Question 17
What is the general formula for Alkanols?
A. CnH2n+2
B. CnH2n+1OH
C. CnH2n
D. CnH2n-2
Answer: B. CnH2n+1OH
Explanation: Alkanols are derived from alkanes by replacing one H with an -OH group.
Question 18
The temporary hardness of water can be removed by:
A. Filtration
B. Boiling
C. Chlorination
D. Decantation
Answer: B. Boiling
Explanation: Boiling decomposes Calcium Hydrogen Trioxocarbonate (IV) which causes temporary hardness.
Question 19
Which of the following is a transition metal?
A. Sodium
B. Calcium
C. Iron
D. Aluminum
Answer: C. Iron
Explanation: Iron is in the d-block of the periodic table, characteristic of transition metals.
Question 20
The noble gas used to provide an inert atmosphere in light bulbs is:
A. Helium
B. Neon
C. Argon
D. Radon
Answer: C. Argon
Explanation: Argon is unreactive and prevents the filament from burning out.
Question 21
An element with atomic number 9 is a:
A. Metal
B. Noble gas
C. Halogen
D. Alkali metal
Answer: C. Halogen
Explanation: Atomic number 9 is Fluorine, a member of the halogen group.
Question 22
Which type of bonding involves the "sea of electrons"?
A. Ionic
B. Covalent
C. Metallic
D. Dative
Answer: C. Metallic
Explanation: Metallic bonds consist of positive ions held together by a cloud of delocalized electrons.
Question 23
What color is the flame when Copper is heated?
A. Lilac
B. Golden yellow
C. Bluish-green
D. Brick red
Answer: C. Bluish-green
Explanation: Copper ions give a characteristic green or bluish-green color in a flame test.
Question 24
The process of converting vapor into liquid is called:
A. Evaporation
B. Sublimation
C. Condensation
D. Melting
Answer: C. Condensation
Explanation: Condensation is the reverse of evaporation.
Question 25
The catalyst used in the manufacture of sulfuric acid by the Contact process is:
A. Finely divided iron
B. Vanadium (V) oxide
C. Platinum
D. Manganese (IV) oxide
Answer: B. Vanadium (V) oxide
Explanation: V2O5 is the modern catalyst used for the oxidation of SO2 to SO3.
Question 26
What is the oxidation number of sulfur in H2S?
A. -2
B. +2
C. +4
D. +6
Answer: A. -2
Explanation: 2(+1) + S = 0. Therefore S = -2.
Question 27
Compounds with the same molecular formula but different structural arrangements are:
A. Isotopes
B. Allotropes
C. Isomers
D. Homologues
Answer: C. Isomers
Explanation: Isomerism is common in organic chemistry, such as butane and 2-methylpropane.
Question 28
Which of the following is a property of an endothermic reaction?
A. Heat is released
B. Temperature of surroundings increases
C. Enthalpy change is positive
D. It occurs spontaneously at all temperatures
Answer: C. Enthalpy change is positive
Explanation: Endothermic reactions absorb heat, so Delta H is positive.
Question 29
The gas that turns lime water milky is:
A. Oxygen
B. Carbon (II) oxide
C. Carbon (IV) oxide
D. Nitrogen
Answer: C. Carbon (IV) oxide
Explanation: CO2 reacts with lime water to form insoluble Calcium Carbonate.
Question 30
Which of the following metals can be found free in nature?
A. Sodium
B. Calcium
C. Gold
D. Magnesium
Answer: C. Gold
Explanation: Gold is very unreactive (noble metal) and does not easily form compounds.
Question 31
The primary reason for galvanizing iron is to prevent:
A. Melting
B. Rusting
C. Evaporation
D. Conductivity
Answer: B. Rusting
Explanation: Zinc is coated on iron to protect it from moisture and oxygen.
Question 32
What is the pH of a solution containing 0.001 mol/dm3 of HCl?
A. 1
B. 2
C. 3
D. 4
Answer: C. 3
Explanation: pH = -log[H+]. -log(10^-3) = 3.
Question 33
A mixture of sand and salt can be separated by:
A. Sublimation
B. Distillation
C. Dissolving in water, filtering, and evaporating
D. Chromatography
Answer: C. Dissolving in water, filtering, and evaporating
Explanation: Salt dissolves, sand does not. Filtering removes sand, and evaporation recovers salt.
Question 34
Which of the following is a natural polymer?
A. Nylon
B. Terylene
C. Cellulose
D. Polyethene
Answer: C. Cellulose
Explanation: Cellulose is a polymer of glucose found in plants.
Question 35
How many structural isomers does Butane (C4H10) have?
A. 2
B. 3
C. 4
D. 5
Answer: A. 2
Explanation: n-butane and 2-methylpropane.
Question 36
The gas used in the vulcanization of rubber is:
A. Oxygen
B. Chlorine
C. Sulfur
D. Hydrogen
Answer: C. Sulfur
Explanation: Sulfur is added to rubber to make it tougher and more heat-resistant.
Question 37
Which subatomic particle orbits the nucleus?
A. Proton
B. Neutron
C. Electron
D. Nucleon
Answer: C. Electron
Explanation: Electrons are found in shells around the central nucleus.
Question 38
The functional group of Alkanoates (Esters) is:
A. -OH
B. -CHO
C. -COOR
D. -COOH
Answer: C. -COOR
Explanation: Alkanoates are formed by the reaction of an alcohol and an acid.
Question 39
The solubility of a gas in water generally ______ as temperature increases.
A. Increases
B. Decreases
C. Stays the same
D. Doubles
Answer: B. Decreases
Explanation: Gases escape the liquid faster as the temperature rises.
Question 40
Which of the following elements is a liquid at room temperature?
A. Chlorine
B. Bromine
C. Iodine
D. Fluorine
Answer: B. Bromine
Explanation: Bromine is one of the only two elements (the other is Mercury) that are liquid at standard conditions.
Question 41
In the reaction: Zn + CuSO4 -> ZnSO4 + Cu, Zinc is acting as a/an:
A. Oxidizing agent
B. Reducing agent
C. Catalyst
D. Dehydrating agent
Answer: B. Reducing agent
Explanation: Zinc loses electrons (is oxidized) and causes Copper ions to be reduced.
Question 42
Which of the following gases has a rotten egg smell?
A. NH3
B. SO2
C. H2S
D. CO2
Answer: C. H2S
Explanation: Hydrogen sulfide is notorious for its foul, rotten egg odor.
Question 43
The bond formed when an atom with a lone pair of electrons shares it with an electron-deficient atom is:
A. Covalent
B. Ionic
C. Dative (Coordinate)
D. Hydrogen
Answer: C. Dative (Coordinate)
Explanation: This occurs in the formation of the Ammonium ion (NH4+).
Question 44
What is the product formed at the cathode during the electrolysis of molten NaCl?
A. Chlorine gas
B. Sodium metal
C. Hydrogen gas
D. Oxygen gas
Answer: B. Sodium metal
Explanation: Sodium ions gain electrons (reduction) at the cathode to form neutral sodium atoms.
Question 45
Which of the following is an amphoteric oxide?
A. Na2O
B. CaO
C. ZnO
D. SO2
Answer: C. ZnO
Explanation: Zinc oxide reacts with both acids and strong bases.
Question 46
The major constituent of the gas used for domestic cooking (LPG) is:
A. Methane
B. Ethane
C. Butane
D. Pentane
Answer: C. Butane
Explanation: LPG is mostly a mixture of propane and butane.
Question 47
The term used to describe the heat content of a system is:
A. Entropy
B. Enthalpy
C. Energy
D. Power
Answer: B. Enthalpy
Explanation: Enthalpy (H) represents the total heat content of a chemical system.
Question 48
Which of the following is an example of a synthetic fiber?
A. Cotton
B. Wool
C. Nylon
D. Silk
Answer: C. Nylon
Explanation: Nylon is an artificially manufactured polyamide.
Question 49
Water gas is a mixture of:
A. CO and N2
B. CO and H2
C. CO2 and H2
D. CH4 and H2O
Answer: B. CO and H2
Explanation: Water gas is produced by passing steam over red-hot coke.
Question 50
Which of the following is the chief ore of lead?
A. Galena
B. Bauxite
C. Cassiterite
D. Haematite
Answer: A. Galena
Explanation: Galena is Lead (II) sulfide (PbS).