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INTRODUCTION
2025 JAMB Chemistry Mock Questions and Answers EXPO, Students need to prepare for the Joint Admissions and Matriculation Board (JAMB) Unified Tertiary Matriculation Examination (UTME) to be conducted in 2025. The success in Chemistry leads to many science-based courses so students need to perform strict preparation. Preparing for the 2025 Joint Admissions and Matriculation Board (JAMB) Unified Tertiary Matriculation Examination (UTME) requires solving realistic practice questions as the main study method.
This post provides compiled 2025 JAMB Chemistry Mock questions and answers did recently to assist your concept learning while helping you discover your weak points.
2025 JAMB Chemistry Mock Questions and Answers
1. What is the component of water gas
A. CO2 and H2
B. CO and H2
C. CO2 and N2
D. CO and N2
Topic: Industrial Chemistry / Gaseous Fuels
Correct Answer: B. CO and H2
Explanation:
Water Gas Definition: Water gas (also known as syngas or synthesis gas, though compositions can vary) is a fuel gas mixture.
Production: It is typically produced by passing steam (H₂O) over red-hot coke (carbon, C) at high temperatures (around 1000 °C).
Reaction: C(s) + H₂O(g) → CO(g) + H₂(g)
2. An aqueous solution of glucose will
A. Boil at a higher temperature than pure water
B. Boil at a lower temperature than pure water
C. have the same boiling point as pure water
Topic: Physical Chemistry / Solutions / Colligative Properties
Correct Answer: A. Boil at a higher temperature than pure water
Explanation:
Colligative Properties: These are properties of solutions that depend on the concentration of solute particles (molecules or ions), but not on the identity of the solute. Boiling point elevation is one such property.
Boiling Point Elevation: When a non-volatile solute (like glucose) is dissolved in a solvent (like water), the vapor pressure of the solvent above the solution is lowered. Because boiling occurs when the vapor pressure equals the external atmospheric pressure, a higher temperature is required to reach that vapor pressure.
3. Co-ordinate bonding occurs in
A. Atoms with lone pair of electrons
B. atoms with unpaired electrons
C. atoms with readily pairing electrons
D. Atoms with bonded electrons
Topic: Chemical Bonding
Correct Answer: A. Atoms with lone pair of electrons
Explanation:
Coordinate Covalent Bond (Dative Bond): This is a type of covalent bond where both electrons in the shared pair come from only one of the two atoms involved in the bond.
Requirement: For an atom to form a coordinate bond, it must possess a lone pair of electrons (a pair of valence electrons not involved in other bonds) that it can donate to another atom or ion that has a vacant orbital capable of accepting the electron pair.
Example: In the formation of the ammonium ion (NH₄⁺), the nitrogen atom in ammonia (NH₃) has a lone pair which it donates to a proton (H⁺, which has an empty 1s orbital).
4. Which of the following absorbs water from the atmosphere to become dilute
A. Effervescence
B. Deliquescence
C. Hygroscopic
D. Efflorescence
Topic: Physical Chemistry / Properties of Substances
Correct Answer: B. Deliquescence
Explanation:
Effervescence: The escape of gas from an aqueous solution (like CO₂ from soda water).
Deliquescence: The process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution. Deliquescent substances become visibly wet or liquid. Example: Solid NaOH pellets exposed to moist air.
Hygroscopic: Describes substances that tend to absorb moisture from the air. This is a broader term. A hygroscopic substance may or may not dissolve in the absorbed water (e.g., concentrated H₂SO₄ is hygroscopic but already liquid; anhydrous CuSO₄ is hygroscopic and changes color but doesn’t necessarily dissolve immediately). Deliquescence is an extreme form of hygroscopy.
Efflorescence: The process where a hydrated salt loses water of crystallization to the atmosphere when the surrounding air is dry, often becoming powdery. Example: Washing soda (Na₂CO₃·10H₂O) crystals losing water.
5. Which of the following is used in miners lamp
A. C2H2
B. CH3CH2OH
C. C2H4
D. CH3COOH
Topic: Organic Chemistry / Hydrocarbons / History of Technology
Correct Answer: A. C2H2
Explanation:
Traditional Miner’s Lamp (Carbide Lamp): Historically, miners used carbide lamps before the widespread adoption of electric lamps.
Chemical Reaction: These lamps worked by reacting calcium carbide (CaC₂) with water (H₂O) to produce acetylene gas (C₂H₂) , which was then burned to produce light.
CaC₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + C₂H₂(g)
Acetylene: C₂H₂ (ethyne) burns with a bright flame.
6. H2 + Cl2 ⇌ 2HCl
What is done in order to increase the rate of reaction:
A. by performing the experiment in a dimly lit room
B. by cooling the system
C. By removing hcl as soon as it is produced
D. by increasing the volume
Topic: Chemical Kinetics / Chemical Equilibrium
Correct Answer: C. By removing hcl as soon as it is produced
Explanation:
Rate of Reaction Factors: Reaction rates are affected by temperature, concentration (or pressure for gases), surface area (for heterogeneous reactions), catalysts, and light (for photochemical reactions).
Reaction H₂ + Cl₂: This reaction is known to be photochemical (initiated by light, especially UV) and generally fast once initiated.
7. Which of these has a characteristic sweet smell and is gotten by the action of cold water on calcium carbide
A. CH3
B. C2H2
C. C4H10
D. C2H5COOCH3
Topic: Organic Chemistry / Hydrocarbons
Correct Answer: B. C2H2
Explanation:
Reaction: As explained in Q5, calcium carbide (CaC₂) reacts with water to produce acetylene (C₂H₂).
CaC₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + C₂H₂(g)
Properties of Acetylene (C₂H₂): Pure acetylene is often described as having a faint, somewhat ethereal or “sweetish” odor, although impurities (like phosphine, PH₃) generated from impure calcium carbide often give it a garlic-like or unpleasant smell. Option D (C₂H₅COOCH₃, Methyl propanoate) is an ester and does have a sweet, fruity smell, but it is not produced from calcium carbide and water. Given the production method stated, C₂H₂ is the intended answer despite the potential ambiguity of its smell description. CH₃ (A) is a methyl radical, not a stable compound. C₄H₁₀ (C) is butane, an alkane with little odor.
8. C2H5OH + CH3COOH → C2H5COOCH3 + H2O
What is the process called when it is reversed
A. Esterification
B. Hydrolysis
C. Dehydration
D. Vulcanization
Topic: Organic Chemistry / Reactions of Functional Groups
Correct Answer: B. Hydrolysis
Explanation:
Forward Reaction (Corrected): C₂H₅OH (Ethanol) + CH₃COOH (Acetic Acid) ⇌ CH₃COOC₂H₅ (Ethyl Acetate) + H₂O. This forward reaction is Esterification, where an alcohol reacts with a carboxylic acid to form an ester and water.
Reverse Reaction: CH₃COOC₂H₅ (Ethyl Acetate) + H₂O ⇌ C₂H₅OH (Ethanol) + CH₃COOH (Acetic Acid). This reverse reaction, where an ester reacts with water (often catalyzed by acid or base) to break down into the original alcohol and carboxylic acid, is called Hydrolysis (specifically, ester hydrolysis).
9. 3CuO(s) + 2NH3(g) → 3Cu(s) + 3H2O2 + N2(g) In the above reaction, ammonia gas acts as?
(Options not provided in the image)
Topic: Redox Reactions
Correct Answer: Reducing Agent (Based on analysis, options not provided)
Explanation:
Assign Oxidation States (Assuming product is H₂O):
Reactants: Cu in CuO is +2; O is -2. N in NH₃ is -3; H is +1.
Products: Cu in Cu(s) is 0. H in H₂O is +1; O is -2. N in N₂(g) is 0.
Identify Changes:
Copper: Oxidation state changes from +2 (in CuO) to 0 (in Cu). This is a decrease, meaning Cu has been reduced.
Nitrogen: Oxidation state changes from -3 (in NH₃) to 0 (in N₂). This is an increase, meaning N has been oxidized.
Define Roles:
The substance that is oxidized (NH₃) causes the reduction of the other substance (CuO). Therefore, NH₃ is the reducing agent.
The substance that is reduced (CuO) causes the oxidation of the other substance (NH₃). Therefore, CuO is the oxidizing agent.
10. 3Fe+4H2O → Fe3O4 + 4H2 in the reaction above the reducing agent is?
(Options not provided in the image)
Topic: Redox Reactions
Correct Answer: Fe (Iron) (Based on analysis, options not provided)
Explanation:
Assign Oxidation States:
Reactants: Fe in Fe(s) is 0. H in H₂O is +1; O is -2.
Products: Fe in Fe₃O₄ (magnetite) has a mixed oxidation state (one Fe²⁺ and two Fe³⁺, average +8/3). H in H₂(g) is 0.
Identify Changes:
Iron: Oxidation state changes from 0 (in Fe) to positive values (+2 and +3, average +8/3) in Fe₃O₄. This is an increase, meaning Fe has been oxidized.
Hydrogen: Oxidation state changes from +1 (in H₂O) to 0 (in H₂). This is a decrease, meaning H has been reduced.
Define Roles:
The substance that is oxidized (Fe) causes the reduction of the other substance (H₂O). Therefore, Fe is the reducing agent.
The substance that is reduced (H₂O) causes the oxidation of the other substance (Fe). Therefore, H₂O is the oxidizing agent.
11. An organic compound that can undergo addition reaction is?
A. Butanamine
B. Butane
C. Butanol
D. Butene
Topic: Organic Chemistry / Types of Reactions
Correct Answer: D. Butene
Explanation:
Addition Reactions: These reactions typically occur in compounds containing multiple bonds (double or triple bonds) or small rings. An atom or group of atoms is added across the multiple bond, breaking one of the bonds (the pi bond) while the sigma bond remains intact.
Analyzing Options:
A. Butanamine (CH₃CH₂CH₂CH₂NH₂): Contains only single bonds between carbons and a C-N single bond. Primarily undergoes substitution or acid-base reactions.
B. Butane (CH₃CH₂CH₂CH₃): An alkane, contains only C-C and C-H single bonds. Primarily undergoes substitution (e.g., halogenation) or combustion.
C. Butanol (e.g., CH₃CH₂CH₂CH₂OH): An alcohol, contains only single bonds between carbons. Primarily undergoes substitution, elimination (dehydration), or oxidation.
D. Butene (e.g., CH₃CH=CHCH₃ or CH₂=CHCH₂CH₃): An alkene, contains a C=C double bond. This double bond readily undergoes addition reactions (e.g., with H₂, Br₂, HBr, H₂O).
12. Sulphur(IV)oxide can be used as a ?
A. Coating Agent
B. Dehydrating agent
C. Refrigerant
D. Drying agent
Topic: Inorganic Chemistry / Uses of Compounds
Correct Answer: C. Refrigerant (or D. Drying agent – see explanation)
Explanation:
Sulphur(IV) oxide (Sulfur Dioxide, SO₂): This gas has several uses.
Analyzing Options:
A. Coating Agent: Not a typical use.
B. Dehydrating agent: Incorrect. SO₂ reacts with water to form sulfurous acid (H₂SO₃). Concentrated H₂SO₄ (Sulfur(VI)) is a dehydrating agent.
C. Refrigerant: Yes, liquid SO₂ was used as an early refrigerant due to its suitable boiling point (-10 °C) and heat of vaporization, although it’s toxic and corrosive, so largely replaced.
D. Drying agent: Generally incorrect as it reacts with water. However, it can act as a reducing agent, and sometimes ‘drying’ might informally refer to removing oxygen (acting as an antioxidant/preservative), which SO₂ does. Also, it can be used to dry certain acidic liquids where its own acidic nature doesn’t interfere.
13. CH3CHO + NaBH4 → ‘x’
The product ‘X’ above is?
A. CH2=CH2
B. CH3CH3
C. CH3CH2OH
D. CH3COOH
Topic: Organic Chemistry / Reduction Reactions
Correct Answer: C. CH₃CH₂OH
Explanation:
Reactants: CH₃CHO is ethanal (an aldehyde). NaBH₄ is sodium borohydride, a common laboratory reducing agent.
Reaction: Sodium borohydride selectively reduces aldehydes to primary alcohols and ketones to secondary alcohols. It does not typically reduce carboxylic acids or esters under normal conditions.
Applying to Ethanal: NaBH₄ provides hydride ions (H⁻) which attack the carbonyl carbon of the aldehyde. Subsequent protonation (usually from the solvent, like water or methanol used during workup) yields the alcohol.
CH₃CHO (Ethanal) –[NaBH₄]–> CH₃CH₂OH (Ethanol)
14. The quantity of heat electricity consumed when 10A was passed through in 1hr during electrolysis is?
(Options not provided in the image. The phrasing “heat electricity” is ambiguous; it likely refers to quantity of charge (Coulombs) or electrical energy (Joules).)
Topic: Electrochemistry / Basic Electrical Concepts
Correct Answer: 36000 Coulombs (Based on calculation, options not provided)
Explanation:
Quantity of Electricity: This usually refers to the electric charge (Q) transferred.
Formula: Charge (Q) = Current (I) × Time (t)
Given Values:
Current (I) = 10 A (Amperes = Coulombs per second)
Time (t) = 1 hr = 60 minutes/hr × 60 seconds/min = 3600 s
Calculation:
Q = 10 A × 3600 s
Q = 36000 C (Coulombs)
Alternative Interpretation (Energy): If “heat electricity” meant electrical energy (Work, W, often dissipated as heat), the formula is W = V × I × t, where V is the voltage. Since voltage is not given, energy cannot be calculated. Therefore, the most likely interpretation is the quantity of charge.
15. An element undergoes oxidation reaction when:
A. its oxidation number decrease
B. when its oxidation number increase
C. if it is the reducing agent.
D. if it is an oxidizing agent
Topic: Redox Reactions / Definitions
Correct Answer: B. when its oxidation number increase
Explanation:
Oxidation Definition: Oxidation can be defined in several ways:
Loss of electrons (LEO – Loss of Electrons is Oxidation)
Increase in oxidation number (or oxidation state)
Gain of oxygen (in some contexts)
Loss of hydrogen (in some contexts)
Analyzing Options:
A. Oxidation number decrease: This defines reduction.
B. Oxidation number increase: This defines oxidation.
C. If it is the reducing agent: A reducing agent causes reduction in another species, and itself undergoes oxidation. So, undergoing oxidation is why it’s a reducing agent, not the definition of oxidation itself.
D. If it is an oxidizing agent: An oxidizing agent causes oxidation and itself undergoes reduction.
16. An aqueous solution of an oxide which changes blue litmus to red is
A amphoteric
B. acidic
C. neutral
D. basic
Topic: Acids and Bases / Oxides
Correct Answer: B. acidic
Explanation:
Litmus Indicator: Litmus is an acid-base indicator. It turns red in acidic solutions (pH < 7) and blue in basic (alkaline) solutions (pH > 7).
Observation: The solution changes blue litmus to red, indicating the solution is acidic.
Oxides and Acidity: Oxides react with water to form acids or bases (or are neutral/amphoteric).
Acidic oxides (typically non-metal oxides like SO₂, CO₂, P₄O₁₀) react with water to form acids (e.g., SO₂ + H₂O → H₂SO₃).
Basic oxides (typically metal oxides like Na₂O, CaO) react with water to form bases (e.g., CaO + H₂O → Ca(OH)₂).
Amphoteric oxides (like Al₂O₃, ZnO) can react with both acids and bases.
Neutral oxides (like CO, N₂O, H₂O) do not show significant acid-base properties in water.
Conclusion: An oxide forming a solution that turns blue litmus red must be an acidic oxide, forming an acidic solution.
17. A chemical change will be spontaneous when
A. enthalpy change is less than 1
B. entropy is equal to free energy
C. free energy is equal to zero
D. the free energy is less than Zero
Topic: Chemical Thermodynamics / Spontaneity
Correct Answer: D. the free energy is less than Zero
Explanation:
Spontaneity: In thermodynamics, a spontaneous process is one that can occur without the continuous input of external energy.
Gibbs Free Energy (ΔG): The change in Gibbs Free Energy (ΔG) is the key criterion for spontaneity of a process at constant temperature and pressure.
ΔG < 0: The process is spontaneous (exergonic).
ΔG > 0: The process is non-spontaneous (endergonic) in the forward direction (but spontaneous in the reverse).
ΔG = 0: The system is at equilibrium.
18. But-2-ene is an isomer of
A. 2methylpropene
B. 2methylbutene
C. pentene
D. Hex-2-ene
Topic: Organic Chemistry / Isomerism
Correct Answer: A. 2-methylpropene
Explanation:
Isomers: Compounds with the same molecular formula but different arrangements of atoms (different structures).
But-2-ene: CH₃-CH=CH-CH₃. Counting atoms: 4 Carbons, (3+1+1+3) = 8 Hydrogens. Molecular Formula: C₄H₈.
Analyze Options for C₄H₈:
A. 2-methylpropene: CH₂=C(CH₃)CH₃. Counting atoms: 4 Carbons, (2+3+3) = 8 Hydrogens. Molecular Formula: C₄H₈. (Same formula as But-2-ene, different structure – isomer).
B. 2-methylbutene: Structure like CH₂=C(CH₃)CH₂CH₃ or CH₃CH=C(CH₃)CH₃. Both have 5 Carbons. Molecular Formula: C₅H₁₀. (Different formula).
C. Pentene: Any isomer (pent-1-ene, pent-2-ene, etc.) has 5 Carbons. Molecular Formula: C₅H₁₀. (Different formula).
D. Hex-2-ene: CH₃-CH=CH-CH₂-CH₂-CH₃. Has 6 Carbons. Molecular Formula: C₆H₁₂. (Different formula).
Conclusion: But-2-ene and 2-methylpropene both have the formula C₄H₈ and are therefore isomers.
19. A hydrocarbon with vapour density of 21 has 36g of carbon in 1 mole. what homologous series do it belongs to.
A. alkane
B. alkyne
C. alkene
D. alcohol
Topic: Organic Chemistry / Stoichiometry / Molecular Formula Determination
Correct Answer: C. alkene
20. Dust particles dispersed in air is an example of:
A. Aerosols
B. Suspension
C. Emulsion
D. Colloid
Topic: Physical Chemistry / Colloids and Dispersions
Correct Answer: A. Aerosols
Explanation:
Colloidal Dispersions: Systems where one substance of microscopically dispersed insoluble particles is suspended throughout another substance. The dispersed-phase particles have a size between 1 and 1000 nanometers.
Types based on Phases:
Aerosol: Dispersed phase is solid OR liquid; dispersion medium is gas. (Examples: Smoke [solid in gas], Fog/Mist [liquid in gas]).
Suspension: Larger solid particles dispersed in a liquid (particles tend to settle). Not technically a colloid.
Emulsion: Dispersed phase is liquid; dispersion medium is liquid. (Example: Milk [fat in water]).
Colloid: The general term for such a dispersion.
Dust in Air: Dust particles (solid) dispersed in air (gas) fit the specific definition of an aerosol. While it is a type of colloid, aerosol is the more specific and accurate classification.
21. Benzene like compound are generally called
A. aliphatic
B. aromatic
C. alkenes
D. alcohols
Topic: Organic Chemistry / Classification
Correct Answer: B. aromatic
Explanation:
Benzene: A cyclic hydrocarbon (C₆H₆) with a specific ring structure and delocalized pi electron system that gives it unique stability and reactivity.
Aromatic Compounds: A class of compounds that contain one or more rings with pi electrons delocalized all the way around them. They typically follow Hückel’s rule (4n+2 pi electrons) and exhibit characteristic chemical properties (like substitution rather than addition reactions). Benzene is the archetypal aromatic compound. Compounds containing benzene rings or similar ring systems are called aromatic.
Aliphatic Compounds: Organic compounds (chain or cyclic) that are not aromatic. Includes alkanes, alkenes, alkynes, and their cyclic counterparts (if not aromatic).
Alkenes: Contain C=C double bonds, but not necessarily aromatic.
Alcohols: Contain the -OH functional group. Can be aliphatic or attached to aromatic rings (phenols).
22. Why is aluminum used in making aeroplanes?
A. Its lightness
B. High density
C. It is a good conductor of electricity
D. It is shiny and attractive
Topic: Properties and Uses of Metals
Correct Answer: A. Its lightness
Explanation:
Requirements for Aircraft Materials: Materials used in aircraft construction need a high strength-to-weight ratio. They must be strong enough to withstand the stresses of flight but also as light as possible to improve fuel efficiency and allow the aircraft to lift off and maneuver easily.
Properties of Aluminum: Aluminum is a metal known for its relatively low density (it’s much lighter than steel, for example) while still possessing good strength, especially when alloyed with other metals (like copper, magnesium, silicon – these alloys are often called duralumin). It also has good corrosion resistance due to forming a protective oxide layer.
23. Why is type metal used for plumbing? (Note: This question seems factually incorrect. Type metal is used for printing type, not plumbing. Plumbing often uses copper, PVC, PEX, or sometimes lead (historically) or galvanized steel. The properties listed might relate to plumbing materials, but the premise about type metal is flawed.)
A. Low density
B. Ability to dissolve in water
C. Resistance to corrosion
D. High electrical conductivity
Topic: Alloys / Properties of Materials (Note: This question contains a significant factual error. Type metal is NOT used for plumbing.)
Correct Answer: C. Resistance to corrosion (based on properties needed for plumbing, not type metal)
24. Permalloy is an alloy of:
A. Chromium and Nickel
B. Iron and Chromium
C. Iron and Nickel
D. Copper and Zinc
Topic: Metallurgy / Alloys
Correct Answer: C. Iron and Nickel
25. Aluminium is extracted from:
A. Haematite
B. Bauxite
C. Cassiterite
D. Cryolite
Topic: Metallurgy / Ores
Correct Answer: B. Bauxite
Explanation:
Ore Definition: An ore is a naturally occurring rock or mineral from which a metal or valuable mineral can be profitably extracted.
Aluminum Extraction: The principal commercial ore of aluminum (Al) is Bauxite. Bauxite is not a specific mineral but a rock composed mainly of hydrated aluminum oxides (like gibbsite, boehmite, diaspore).
Extraction Process: Aluminum is extracted from purified aluminum oxide (alumina, Al₂O₃), which is obtained from bauxite, using the Hall-Héroult electrolytic process.
26. The functional groups in glucose is
A. alkanol and alkanone
B. alkanol and alkanal
C. alkanal and alkanone
D. alkanoate and alkanone
Topic: Organic Chemistry / Biochemistry (Functional Groups)
Correct Answer: B. alkanol and alkanal
27. The catalyst used in the Contact Process is:
A. Vanadium(V) oxide
B. Nickel
C. Iron
D. Platinum
Topic: Industrial Chemistry / Catalysis
Correct Answer: A. Vanadium(V) oxide
28. If the principal quantum no is 3, the subshell would be (Note: This question is poorly phrased. A principal quantum number (n=3) contains multiple subshells (s, p, d). The options seem to refer to the number of subshells within that principal level.)
A. 1
B. 2
C. 3
D. 4
Topic: Atomic Structure / Quantum Numbers
Correct Answer: C. 3
Explanation:
Quantum Numbers: The properties of atomic orbitals are described by quantum numbers.
Principal Quantum Number (n): Describes the main energy level (shell). n = 1, 2, 3…
Azimuthal Quantum Number (l): Describes the shape of the orbital and defines the subshell. For a given n, ‘l’ can have integer values from 0 to (n-1).
l = 0 corresponds to the ‘s’ subshell.
l = 1 corresponds to the ‘p’ subshell.
l = 2 corresponds to the ‘d’ subshell.
l = 3 corresponds to the ‘f’ subshell.
Subshells for n=3: If the principal quantum number n = 3:
The possible values for ‘l’ are 0, 1, and (3-1) = 2.
l = 0 corresponds to the 3s subshell.
l = 1 corresponds to the 3p subshell.
l = 2 corresponds to the 3d subshell.
Number of Subshells: There are three distinct subshells (s, p, and d) within the n=3 principal energy level.
Interpreting the Question: The question asks “the subshell would be” and gives numerical options. This most likely refers to the count or number of different subshells present in the n=3 shell.
Conclusion: There are 3 subshells (3s, 3p, 3d) when n=3.
29. The product formed when ammonia is bubbled through ethyl ethanoate is ?
A Ethylamine
B Ethanamide
C Butylamine
D Butanamide
Topic: Organic Chemistry (Reactions of Esters)
Correct Answer: B. Ethanamide
30. A sulphide that is insoluble in water is ?
A CaS
B MgS
C ZnS
D BaS
Topic: Inorganic Chemistry (Solubility Rules)
Correct Answer: C. ZnS
Explanation:
General Solubility Rules for Sulfides (S²⁻): Most metal sulfides are insoluble in water.
Exceptions: The main exceptions are the sulfides of Group 1 metals (like Na₂S, K₂S) and Group 2 metals (CaS, SrS, BaS), as well as ammonium sulfide ((NH₄)₂S). These are generally considered soluble or at least readily react/hydrolyze in water.
31. Mortar is hardened by:
A. Fermentation
B. Oxidation
C. Hydration
D. Sublimation
Topic: Materials Chemistry / Applied Chemistry (Cement Chemistry)
Correct Answer: C. Hydration
Explanation:
Mortar Composition: Mortar is typically a mixture of a binder (like cement or lime), fine aggregate (like sand), and water.
Hardening Process: The primary hardening mechanism for modern cement-based mortars is hydration. When water is added, the chemical components of the cement (mainly calcium silicates and aluminates) react with water molecules.
32. The screening effect of inner electrons is one of the factors that affects the magnitude of ?
A Electron affinity
B Electronegativity
C ionization energy
D Atomic size
Topic: Atomic Structure and Periodicity
Correct Answer: C. ionization energy (although it affects all options to some degree)
33. Bronze is an alloy of ?
A copper and tin
B copper and zinc
C nickel and tin
D nickel and copper
Topic: Materials Science / Metallurgy (Alloys)
Correct Answer: A. copper and tin
Explanation:
Alloy Definition: An alloy is a mixture composed primarily of a metal and usually one or more other elements (which can be metals or non-metals).
Bronze: Bronze is historically one of the most important alloys. It is primarily composed of copper (Cu), with tin (Sn) as the main alloying element. Other elements like phosphorus, manganese, aluminum, or silicon may sometimes be added to create specific types of bronze with varying properties.
34. What volume of distilled water will be added to a 25cm³ volume of a standard solution to dilute it to ten Times ?
A 250cm³
B 255cm³
C 225cm³
D 275cm³
Topic: Solution Chemistry (Concentration and Dilution)
Correct Answer: C. 225cm³
Explanation:
Understanding Dilution: “Dilute it to ten times” typically means the final volume should be ten times the initial volume, resulting in a concentration that is one-tenth of the original concentration.
Initial Volume (V₁): V₁ = 25 cm³
Final Volume (V₂): The final volume needs to be 10 times the initial volume.
V₂ = 10 * V₁
V₂ = 10 * 25 cm³
V₂ = 250 cm³
Volume of Water Added: The question asks for the volume of distilled water added to the initial solution to reach the final volume.
Volume Added = Final Volume – Initial Volume
Volume Added = V₂ – V₁
Volume Added = 250 cm³ – 25 cm³
Volume Added = 225 cm³
Conclusion: 225 cm³ of distilled water must be added to the initial 25 cm³ solution to achieve a final volume of 250 cm³ (a tenfold dilution by volume).
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Conclusion
Success in the 2025 JAMB Chemistry exam hinges on diligent preparation and smart practice. Your ability to score high in the 2025 JAMB Chemistry exam will improve dramatically when you use these 2025 JAMB Chemistry Mock questions and answers along with proper explanation understanding and a well-organized study strategy. Strategic practice combined with constant effort function as essential tools to open the doorway toward successful UTME performance. Begin using this set of 2025 JAMB Chemistry Mock questions and answers now to build confident academic prospects.
