Sample WAEC-style Practice Questions (Original Content)
WAEC Style
Question 1
Which of the following elements has the highest first ionization energy?
A. Sodium
B. Magnesium
C. Aluminum
D. Argon
Answer: D. Argon
Explanation: Ionization energy increases across a period. Argon, being a noble gas with a stable octet, requires the most energy to remove an electron.
Question 2
The type of bond formed between two non-metal atoms of different electronegativities is a:
A. Non-polar covalent bond
B. Polar covalent bond
C. Ionic bond
D. Metallic bond
Answer: B. Polar covalent bond
Explanation: When electronegativities differ, the shared electron pair is pulled closer to the more electronegative atom, creating poles.
Question 3
How many protons, neutrons, and electrons are in an atom of 23 Na 11?
A. 11 protons, 12 neutrons, 11 electrons
B. 11 protons, 11 neutrons, 12 electrons
C. 12 protons, 11 neutrons, 11 electrons
D. 11 protons, 23 neutrons, 11 electrons
Answer: A. 11 protons, 12 neutrons, 11 electrons
Explanation: Atomic number (11) = protons and electrons. Neutrons = Mass number (23) - Atomic number (11) = 12.
Question 4
Which of the following is an intensive property of matter?
A. Mass
B. Volume
C. Density
D. Length
Answer: C. Density
Explanation: Intensive properties do not depend on the amount of matter present. Density remains the same regardless of sample size.
Question 5
The geometric shape of a methane (CH4) molecule is:
A. Linear
B. Trigonal planar
C. Tetrahedral
D. Octahedral
Answer: C. Tetrahedral
Explanation: Methane has four bonding pairs and zero lone pairs, resulting in a tetrahedral shape with 109.5 degree angles.
Question 6
Which of the following gases is used as a refrigerant?
A. Oxygen
B. Ammonia
C. Nitrogen
D. Hydrogen
Answer: B. Ammonia
Explanation: Ammonia is widely used in industrial refrigeration because of its high latent heat of vaporization.
Question 7
The empirical formula of a compound containing 40% Carbon, 6.7% Hydrogen, and 53.3% Oxygen is: (C=12, H=1, O=16)
A. CHO
B. CH2O
C. C2H4O
D. C2H2O2
Answer: B. CH2O
Explanation: Moles: C=40/12=3.33; H=6.7/1=6.7; O=53.3/16=3.33. Ratio: 1:2:1.
Question 8
Which of the following salts is insoluble in water?
A. Sodium trioxocarbonate (IV)
B. Potassium chloride
C. Barium tetraoxosulfate (VI)
D. Calcium hydrogen trioxocarbonate (IV)
Answer: C. Barium tetraoxosulfate (VI)
Explanation: Most sulfates are soluble, but Barium, Calcium, and Lead sulfates are notable exceptions.
Question 9
The change of a gas to a liquid is called:
A. Evaporation
B. Sublimation
C. Condensation
D. Freezing
Answer: C. Condensation
Explanation: Condensation is the process where a gas loses heat and changes into the liquid state.
Question 10
What is the oxidation state of Manganese in KMnO4?
A gas occupies 2.0 dm3 at 27 degrees Celsius. What is its volume at 127 degrees Celsius at constant pressure?
A. 2.67 dm3
B. 3.0 dm3
C. 1.5 dm3
D. 4.0 dm3
Answer: A. 2.67 dm3
Explanation: Use Charles's Law (V1/T1 = V2/T2). Convert to Kelvin: T1=300K, T2=400K. 2.0/300 = V2/400. V2 = 2.67.
Question 12
Which of the following is the chief ore of Iron?
A. Bauxite
B. Haematite
C. Cassiterite
D. Galena
Answer: B. Haematite
Explanation: Haematite (Fe2O3) is the primary ore used in the blast furnace to extract iron.
Question 13
Which of the following is a greenhouse gas?
A. Oxygen
B. Helium
C. Methane
D. Argon
Answer: C. Methane
Explanation: Methane (CH4) is a potent greenhouse gas that contributes to global warming.
Question 14
The process of breaking down large hydrocarbon molecules into smaller ones is:
A. Polymerization
B. Cracking
C. Isomerization
D. Substitution
Answer: B. Cracking
Explanation: Cracking is used in the petroleum industry to produce smaller, more useful molecules like petrol.
Question 15
In the reaction: H2 + Cl2 -> 2HCl, which substance is oxidized?
A. Hydrogen
B. Chlorine
C. Hydrogen chloride
D. None of the above
Answer: A. Hydrogen
Explanation: The oxidation state of Hydrogen increases from 0 to +1, meaning it lost electrons (oxidized).
Question 16
The general formula for the Alkyne series is:
A. CnH2n+2
B. CnH2n
C. CnH2n-2
D. CnHn
Answer: C. CnH2n-2
Explanation: Alkynes are unsaturated hydrocarbons containing a carbon-carbon triple bond.
Question 17
Which of the following solutions will turn blue litmus paper red?
A. Sodium hydroxide
B. Ammonia solution
C. Hydrochloric acid
D. Sodium chloride
Answer: C. Hydrochloric acid
Explanation: Acids turn blue litmus paper red.
Question 18
The bond formed between a metal and a non-metal is usually:
A. Covalent
B. Metallic
C. Ionic (Electrovalent)
D. Dative
Answer: C. Ionic (Electrovalent)
Explanation: This occurs when electrons are transferred from the metal atom to the non-metal atom.
Question 19
How many electrons are shared in a double covalent bond?
A. 2
B. 4
C. 6
D. 8
Answer: B. 4
Explanation: A double bond consists of two pairs of shared electrons, making 4 electrons total.
Question 20
Which of the following is a neutralization reaction?
A. Acid + Metal -> Salt + Hydrogen
B. Acid + Base -> Salt + Water
C. Acid + Carbonate -> Salt + Water + CO2
D. Salt + Salt -> New Salt + New Salt
Answer: B. Acid + Base -> Salt + Water
Explanation: This is the classic definition of a neutralization reaction.
Question 21
What is the IUPAC name for CH3CH2CH2OH?
A. Methanol
B. Ethanol
C. Propan-1-ol
D. Butanol
Answer: C. Propan-1-ol
Explanation: The chain has 3 carbon atoms (propane) and an alcohol group (-OH) on the first carbon.
Question 22
The process by which vegetable oil is converted to margarine is:
A. Oxidation
B. Saponification
C. Hydrogenation
D. Esterification
Answer: C. Hydrogenation
Explanation: Adding hydrogen to unsaturated fats in the presence of a nickel catalyst makes them solid.
Question 23
Which of the following is the most reactive metal?
A. Copper
B. Iron
C. Potassium
D. Gold
Answer: C. Potassium
Explanation: Potassium is at the top of the reactivity series among the options listed.
Question 24
The formula for the trioxonitrate (V) acid is:
A. HNO2
B. HNO3
C. H2NO3
D. NH3
Answer: B. HNO3
Explanation: This is Nitric acid, where Nitrogen has an oxidation state of +5.
Question 25
Which of the following is a member of the transition metal series?
A. Sodium
B. Calcium
C. Iron
D. Magnesium
Answer: C. Iron
Explanation: Transition metals are found in the d-block of the periodic table (Groups 3-12).
Question 26
Anhydrous Calcium Chloride is used as a:
A. Catalyst
B. Drying agent (desiccant)
C. Indicator
D. Reducing agent
Answer: B. Drying agent (desiccant)
Explanation: It is deliquescent and absorbs moisture from gases or organic liquids.
Question 27
Which of the following isotopes is used in dating archaeological artifacts?
A. Carbon-12
B. Carbon-14
C. Uranium-235
D. Iodine-131
Answer: B. Carbon-14
Explanation: Radiocarbon dating uses the decay of C-14 to estimate the age of once-living materials.
Question 28
What is the percentage by mass of Oxygen in Water (H2O)? (H=1, O=16)
A. 11.1%
B. 33.3%
C. 88.9%
D. 50%
Answer: C. 88.9%
Explanation: Molar mass = 18. %O = (16/18) * 100 = 88.88...%.
Question 29
The ability of an atom to attract electrons to itself in a chemical bond is:
A. Electron affinity
B. Electronegativity
C. Ionization energy
D. Electropositivity
Answer: B. Electronegativity
Explanation: Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
Question 30
The substance used to test for the presence of Glucose in a lab is:
A. Benedict's solution
B. Iodine solution
C. Litmus solution
D. Phenolphthalein
Answer: A. Benedict's solution
Explanation: Benedict's (or Fehling's) solution turns from blue to brick-red in the presence of a reducing sugar like glucose.
Question 31
Which of the following allotropes of Carbon is a good conductor of electricity?
A. Diamond
B. Graphite
C. Coal
D. Coke
Answer: B. Graphite
Explanation: Graphite has delocalized electrons between its layers, allowing it to conduct electricity.
Question 32
The volume of 0.1 mol/dm3 HCl required to neutralize 25 cm3 of 0.2 mol/dm3 NaOH is:
Answer: C. Saponification
Explanation: It involves the alkaline hydrolysis of fats and oils to produce soap and glycerol.
Question 40
Which of the following is an amphoteric oxide?
A. Na2O
B. MgO
C. Al2O3
D. SO2
Answer: C. Al2O3
Explanation: Aluminum oxide reacts with both acids and bases.
Question 41
The acid present in sour milk is:
A. Ethanoic acid
B. Lactic acid
C. Citric acid
D. Methanoic acid
Answer: B. Lactic acid
Explanation: Lactic acid is produced by the bacterial fermentation of lactose in milk.
Question 42
Temporary hardness in water can be removed by:
A. Filtration
B. Boiling
C. Adding common salt
D. Distillation only
Answer: B. Boiling
Explanation: Boiling decomposes the dissolved calcium hydrogen trioxocarbonate (IV) into insoluble calcium trioxocarbonate (IV).
Question 43
The product formed when ethene reacts with bromine water is:
A. Bromoethane
B. 1,2-dibromoethane
C. 1,1-dibromoethane
D. Ethane
Answer: B. 1,2-dibromoethane
Explanation: This is an addition reaction across the double bond of the alkene.
Question 44
Which of the following is a vector quantity in chemistry?
A. Temperature
B. Reaction rate
C. Dipole moment
D. Concentration
Answer: C. Dipole moment
Explanation: Dipole moment has both magnitude and a specific direction (from positive to negative pole).
Question 45
The salt obtained from the reaction between aqueous ammonia and sulfuric acid is:
A. Ammonium sulfate
B. Ammonia sulfate
C. Ammonium sulfite
D. Nitrogen sulfate
Answer: A. Ammonium sulfate
Explanation: (NH4)2SO4 is formed through neutralization.
Question 46
Which of the following methods is used to separate a mixture of oil and water?
A. Sublimation
B. Evaporation
C. Separating funnel
D. Fractional distillation
Answer: C. Separating funnel
Explanation: Oil and water are immiscible liquids and form distinct layers based on density.
Question 47
According to the Kinetic Theory, the pressure of a gas is caused by:
A. Attractive forces between molecules
B. Collisions of molecules with the walls of the container
C. The weight of the molecules
D. The volume of the molecules
Answer: B. Collisions of molecules with the walls of the container
Explanation: Each collision exerts a tiny force, and the sum of these forces over an area is pressure.
Question 48
The monomer used to make PVC is:
A. Ethene
B. Vinyl chloride (Chloroethene)
C. Propene
D. Tetrafluoroethene
Answer: B. Vinyl chloride (Chloroethene)
Explanation: Polyvinyl chloride (PVC) is produced by the polymerization of chloroethene.
Question 49
Which of the following is a use of Chlorine?
A. Filling balloons
B. Sterilizing water
C. Manufacturing margarine
D. Filling light bulbs
Answer: B. Sterilizing water
Explanation: Chlorine kills bacteria and other pathogens in drinking water and swimming pools.
Question 50
The noble gas used in incandescent light bulbs to prevent the filament from burning out is:
A. Helium
B. Neon
C. Argon
D. Radon
Answer: C. Argon
Explanation: Argon provides an inert atmosphere that prevents the Tungsten filament from oxidizing.