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JAMB ChemistryStudy notes & practice

Connect atoms, reactions and calculations to materials, living systems and industry.

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Foundation revision notes and original practice. These notes introduce chemical ideas and selected calculations. They do not provide complete practical or question-bank coverage.

What these revision notes cover
  • These notes introduce chemical ideas and selected calculations. They do not provide complete practical or question-bank coverage.
  • Practical experiments require appropriate instruction and laboratory safety procedures.

01 Physical chemistry

Mixtures, purity and separation

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What you should be able to do

  • Choose separation methods from physical properties
  • Distinguish elements, compounds and mixtures

Understand it

An element contains one type of atom; a compound has elements chemically combined in fixed proportions; a mixture has substances together without a fixed chemical ratio. Physical changes alter form or state, while chemical changes produce different substances.

Separation uses differences in properties. Filtration separates an insoluble solid from a liquid; evaporation recovers a non-volatile solute; distillation collects a volatile liquid. Fractional distillation improves separation of liquids with different but relatively close boiling points.

Chromatography separates substances by different affinities for mobile and stationary phases. Crystallisation exploits changing solubility, sublimation exploits direct solid-to-gas change, and a magnet can remove a magnetic component. Pure substances typically have characteristic sharp melting points at a stated pressure.

Work through an example

How would you recover both salt and water from salt solution?

Explanation: Use simple distillation: water vaporises and is condensed, while the non-volatile salt remains in the vessel.

Watch out: Filtration cannot remove a dissolved salt from its solution.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which method directly collects insoluble sand as a residue while water passes through the apparatus without boiling the mixture?

  1. Sublimation
  2. Filtration
  3. Paper chromatography
  4. Simple distillation to collect only the water
Show answer and explanation

Answer B: Filtration

Sand does not dissolve in water. Its particles remain on the filter paper as the residue while water passes through as the filtrate. Fractional distillation separates suitable liquid mixtures; sublimation requires a component that passes directly from solid to gas. Neither is needed for this mixture.

Question 2

A mixture of coloured soluble dyes is commonly separated by

  1. Magnetisation
  2. Decantation alone
  3. Hand picking
  4. Chromatography
Show answer and explanation

Answer D: Chromatography

In chromatography, dissolved dyes interact differently with the moving solvent and the stationary material, so they travel different distances. Decanting pours off a liquid but does not separate dissolved dyes. A magnet and hand picking do not distinguish these dissolved components.

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02 Physical chemistry

Moles, formulae and chemical equations

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What you should be able to do

  • Use mole ratios in balanced equations
  • Determine empirical formulae and reacting quantities

Understand it

Balanced equations conserve atoms and charge. Coefficients change how many particles react; subscripts belong to the identity of a substance and must not be altered merely to balance an equation. Conservation of mass applies to the complete system.

The mole counts entities. Amount n equals mass divided by molar mass. Concentration c=n/V when V is in dm³ for mol dm⁻³. The coefficients of a balanced equation give mole ratios, not generally mass ratios.

An empirical formula gives the simplest whole-number atom ratio. Divide each element’s mass by its relative atomic mass, then divide the resulting amounts by the smallest. A molecular formula is a whole-number multiple of the empirical formula.

Work through an example

How many moles are in 9 g of water? Use H=1, O=16.

Explanation: Molar mass=18 g mol⁻¹. n=9/18=0.50 mol.

Watch out: Convert cm³ to dm³ by dividing by 1000 before using molar concentration.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

In 2H₂ + O₂ → 2H₂O, 3 mol of O₂ requires how much H₂?

  1. 3 mol
  2. 1.5 mol
  3. 6 mol
  4. 9 mol
Show answer and explanation

Answer C: 6 mol

The H₂:O₂ mole ratio is 2:1, so 6 mol H₂ is required.

Question 2

A solution contains 0.2 mol in 0.5 dm³. Its concentration, in mol dm⁻³, is

  1. 0.1
  2. 0.4
  3. 4.0
  4. 2.5
Show answer and explanation

Answer B: 0.4

c=n/V=0.2/0.5=0.4 mol dm⁻³.

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03 Physical chemistry

Kinetic theory and gas laws

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What you should be able to do

  • Relate particle motion to states and pressure
  • Apply gas laws with consistent units

Understand it

Particles move continuously. Solids have particles vibrating about fixed positions, liquids allow particles to move past neighbours, and gases have widely separated particles. Gas pressure results from particle collisions with container walls.

For a fixed amount of gas, Boyle’s law gives PV constant at fixed temperature; Charles’s law gives V/T constant at fixed pressure. Use absolute temperature in kelvin. The ideal gas equation PV=nRT joins pressure, volume, amount and temperature.

Dalton’s law adds partial pressures of non-reacting gases in an ideal mixture. Graham’s law relates diffusion or effusion rate inversely to the square root of molar mass. Real gases depart most from ideal behaviour when attractions and particle volumes become important, especially at high pressure and low temperature.

Work through an example

A gas occupies 200 cm³ at 100 kPa. Find its volume at 250 kPa at constant temperature.

Explanation: P₁V₁=P₂V₂, so V₂=100×200/250=80 cm³.

Watch out: Charles’s law uses kelvin, not degrees Celsius.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A fixed amount of ideal gas at 300 K is heated to 600 K at constant pressure. Its volume

  1. Stays fixed
  2. Halves
  3. Becomes zero
  4. Doubles
Show answer and explanation

Answer D: Doubles

V is proportional to absolute T, so doubling T doubles V.

Question 2

Which gas diffuses fastest under comparable conditions?

  1. O₂
  2. H₂
  3. CO₂
  4. Cl₂
Show answer and explanation

Answer B: H₂

H₂ has the lowest molar mass, giving the highest diffusion rate.

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04 Atomic chemistry

Atomic structure, isotopes and orbitals

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What you should be able to do

  • Calculate subatomic particle numbers
  • Use simple electronic configurations

Understand it

Atomic number is the number of protons. Mass number is protons plus neutrons. A neutral atom has equal proton and electron counts; ions form by electron loss or gain. Isotopes share atomic number but differ in neutron number.

Electrons occupy orbitals described by quantum numbers. An s subshell holds up to 2 electrons and a p subshell up to 6. Filling follows increasing energy, the Pauli limit of two opposite-spin electrons per orbital, and Hund’s preference for separate equal-energy orbitals before pairing.

For the first twenty elements, common configurations use 1s, 2s, 2p, 3s, 3p and 4s. s orbitals are spherical; p orbitals have two main lobes. Relative atomic mass is a weighted average of isotopic masses, so it need not be a whole number.

Work through an example

For ²³Na⁺ with atomic number 11, find protons, neutrons and electrons.

Explanation: Protons=11; neutrons=23−11=12; electrons=11−1=10.

Watch out: A positive ion has lost electrons, not gained protons.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Isotopes differ in their numbers of

  1. Nuclear charges
  2. Protons
  3. Neutrons
  4. Atomic numbers
Show answer and explanation

Answer C: Neutrons

Their proton number is the same but neutron number differs.

Question 2

The maximum electrons in a p subshell is

  1. 6
  2. 4
  3. 2
  4. 8
Show answer and explanation

Answer A: 6

Three p orbitals each hold up to two electrons.

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05 Atomic chemistry

Periodicity and the periodic table

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What you should be able to do

  • Relate electron configurations to groups and periods
  • Explain broad trends in atomic properties

Understand it

Elements are arranged by increasing atomic number. Periods correspond broadly to occupied principal shells; main-group elements in a group share similar outer-electron arrangements and often similar chemistry. Group 1 contains alkali metals and group 17 contains halogens.

Across a period, increasing nuclear charge generally pulls electrons more strongly while shielding changes less, so atomic radius decreases. Down a group, extra occupied shells generally increase radius and shielding.

Ionisation energy is the energy required to remove an electron from a gaseous atom or ion. Electronegativity describes attraction for bonding electrons. Trends have exceptions, so avoid claiming every property changes perfectly smoothly across every element.

Work through an example

Why is potassium generally more reactive with water than sodium?

Explanation: Its outer electron is farther from the nucleus and more shielded, so it is removed more readily.

Watch out: Ionisation energy and electronegativity describe different processes.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which pair belongs to the same main group?

  1. Na and Mg
  2. Na and K
  3. O and Ne
  4. C and N
Show answer and explanation

Answer B: Na and K

Sodium and potassium are both alkali metals.

Question 2

Atomic radius generally increases down a group mainly because

  1. All electrons are lost
  2. More shells are occupied
  3. Atomic number decreases
  4. The nucleus vanishes
Show answer and explanation

Answer B: More shells are occupied

Additional shells place outer electrons farther from the nucleus.

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06 Atomic chemistry

Bonding, molecular shapes and intermolecular forces

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What you should be able to do

  • Distinguish major bond types
  • Predict simple shapes and property differences

Understand it

Ionic bonding is electrostatic attraction between oppositely charged ions; covalent bonding involves shared electron pairs. A coordinate covalent bond begins with both shared electrons supplied by one atom. Metallic bonding involves positive metal centres and delocalised electrons.

Electron-pair repulsion helps explain shapes. Methane is tetrahedral, ammonia is trigonal pyramidal, water is bent and carbon dioxide is linear. Lone pairs affect the shape, so electron-pair arrangement and molecular shape need not have the same name.

Intermolecular attractions act between particles and influence boiling points. Hydrogen bonding is especially associated with H bonded to N, O or F interacting with a suitable lone pair. It is distinct from the covalent bond within a water molecule.

Work through an example

Why can molten sodium chloride conduct but solid sodium chloride normally cannot?

Explanation: Its ions can move in the liquid, but are held in fixed lattice positions in the solid.

Watch out: Melting a simple molecular substance normally overcomes intermolecular forces, not every covalent bond inside its molecules.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

The shape of CH₄ is

  1. Tetrahedral
  2. Linear
  3. Trigonal pyramidal
  4. Bent
Show answer and explanation

Answer A: Tetrahedral

Four bonding pairs around carbon arrange tetrahedrally.

Question 2

Electrical conduction in a metal is mainly due to

  1. Mobile metal cations through the solid lattice
  2. Neutral molecules carrying charge
  3. Mobile anions through the solid lattice
  4. Mobile electrons
Show answer and explanation

Answer D: Mobile electrons

Delocalised electrons move through the metal.

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07 Atomic chemistry

Nuclear chemistry and radioactivity

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What you should be able to do

  • Compare alpha, beta and gamma radiation
  • Apply half-life and distinguish fission from fusion

Understand it

Radioactive nuclei change spontaneously into more stable arrangements. Alpha particles contain two protons and two neutrons; beta-minus radiation consists of emitted electrons from nuclear conversion; gamma radiation is high-energy electromagnetic radiation.

In alpha decay the mass number falls by 4 and atomic number by 2. In beta-minus decay mass number is unchanged and atomic number rises by 1. Gamma emission changes nuclear energy without changing these numbers.

A half-life is the time for half the undecayed nuclei in a large sample to decay. Fission splits a heavy nucleus; fusion joins light nuclei. Nuclear equations must conserve total charge and nucleon number, even though a small mass change can correspond to a large energy change.

Work through an example

A radioactive sample has mass 80 mg and half-life 4 hours. What mass of the original isotope remains undecayed after 12 hours?

Explanation: Three half-lives pass: 80→40→20→10 mg.

Watch out: Half-life does not mean every atom decays after the same waiting time.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which radiation is an electromagnetic wave?

  1. Alpha
  2. Neutron stream
  3. Beta-minus
  4. Gamma
Show answer and explanation

Answer D: Gamma

Gamma rays are high-energy photons.

Question 2

After alpha decay, mass number changes by

  1. +1
  2. −2
  3. 0
  4. −4
Show answer and explanation

Answer D: −4

An alpha particle carries four nucleons away.

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08 Physical chemistry

Solutions, solubility and colloids

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What you should be able to do

  • Interpret saturation and solubility curves
  • Distinguish true solutions, colloids and suspensions

Understand it

A solution contains solute dispersed at molecular or ionic scale in a solvent. At a stated temperature, a saturated solution is in equilibrium with undissolved solute. A supersaturated solution contains more dissolved solute than the stable saturation amount and can crystallise after disturbance.

Solubility depends on solute, solvent and temperature. A solubility curve shows how the saturated amount changes with temperature; cooling can cause crystallisation when solubility decreases. Always check whether units are mass per solvent mass or amount per solution volume.

Suspensions contain larger particles that may settle and can often be filtered. Colloids have intermediate dispersed particles and can scatter light. Solvent choice reflects interactions: water dissolves many ionic or polar substances, whereas suitable non-polar solvents dissolve many oils.

Work through an example

A solubility curve shows 40 g per 100 g water at a higher temperature and 25 g at a lower temperature. What crystallises on cooling a saturated sample containing 100 g water?

Explanation: 40−25=15 g crystallises, assuming no solvent is lost.

Watch out: A saturated solution is not necessarily highly concentrated compared with another substance.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which system is a typical suspension?

  1. Sand in water
  2. Sodium chloride solution
  3. Pure water
  4. Sugar dissolved in water
Show answer and explanation

Answer A: Sand in water

Sand particles remain separate and settle.

Question 2

A solution that can dissolve more solute at the same temperature is

  1. At crystallisation equilibrium with excess solid
  2. Supersaturated
  3. Saturated
  4. Unsaturated
Show answer and explanation

Answer D: Unsaturated

It is below the saturation limit.

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09 Environmental chemistry

Air, water and soil pollution

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What you should be able to do

  • Identify pollutants and effects
  • Relate control methods to pollution sources

Understand it

Dry air is mainly nitrogen and oxygen, with smaller amounts of argon, carbon dioxide and other gases. Water-vapour content varies. Air is a mixture because its components retain distinct identities and its composition is not a fixed chemical ratio.

Carbon monoxide interferes with oxygen transport; sulfur dioxide and nitrogen oxides contribute to acidic deposition. Fine particles reduce air quality, while some chlorofluorocarbons damage stratospheric ozone. Different pollutants have different chemical and biological effects.

Oil spills, sewage and industrial discharges contaminate water and soil. Biodegradable materials can still cause harm, especially when decomposition uses dissolved oxygen. Treatment, emission controls, safer processes and waste reduction address pollution before it spreads.

Work through an example

Why can untreated organic waste harm aquatic animals even if it decomposes naturally?

Explanation: Microbial decomposition consumes dissolved oxygen, potentially leaving too little for aquatic animals.

Watch out: Biodegradable does not mean harmless in every amount or setting.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

The most abundant gas in dry air is

  1. Carbon dioxide
  2. Hydrogen
  3. Oxygen
  4. Nitrogen
Show answer and explanation

Answer D: Nitrogen

Nitrogen makes up roughly four-fifths of dry air.

Question 2

Which gas is especially associated with reduced oxygen transport in blood?

  1. Helium
  2. Argon
  3. Carbon monoxide
  4. Nitrogen
Show answer and explanation

Answer C: Carbon monoxide

Carbon monoxide binds strongly to haemoglobin and interferes with oxygen delivery.

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10 Physical chemistry

Acids, bases, salts and titration

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What you should be able to do

  • Compare strength and concentration
  • Use neutralisation and pH relationships

Understand it

An acid donates a proton in the Brønsted model; a base accepts one. In water, acidic solutions contain excess hydronium ions. Strong and weak describe extent of ionisation, while concentrated and dilute describe amount per volume.

Neutralisation produces a salt and, in common acid-hydroxide reactions, water. Salt preparation depends on solubility and reactant properties. Some salts hydrolyse to give acidic or alkaline solutions; a salt solution is not automatically neutral.

pH=−log₁₀[H⁺] in the simple dilute-solution treatment. At 25°C, pH+pOH≈14. Titration uses a measured reacting volume and balanced-equation ratio to find an unknown concentration. Buffers resist small pH changes when small amounts of acid or base are added.

Work through an example

Find the pH of a solution with [H⁺]=1×10⁻³ mol dm⁻³.

Explanation: pH=−log₁₀(10⁻³)=3.

Watch out: Equal acid and base volumes do not necessarily contain equivalent reacting amounts.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A weak acid is one that

  1. Ionises only partially in water
  2. Has a lower boiling point than every strong acid
  3. Has fewer than two hydrogen atoms in each molecule
  4. Has a low concentration in every solution
Show answer and explanation

Answer A: Ionises only partially in water

Weakness concerns incomplete ionisation, not concentration.

Question 2

25 cm³ of 0.10 mol dm⁻³ HCl neutralises how many moles of NaOH?

  1. 0.25
  2. 0.00025
  3. 0.0025
  4. 0.025
Show answer and explanation

Answer C: 0.0025

HCl amount=0.10×0.025=0.0025 mol; the reaction ratio with NaOH is 1:1.

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11 Physical chemistry

Oxidation, reduction and oxidation numbers

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What you should be able to do

  • Identify electron transfer and agents
  • Assign oxidation numbers consistently

Understand it

Oxidation is loss of electrons or an increase in oxidation number; reduction is gain of electrons or a decrease. They occur together because electrons lost by one species are gained by another.

An oxidising agent accepts electrons and is reduced. A reducing agent donates electrons and is oxidised. In a simple reaction of zinc with copper(II) ions, zinc is oxidised while copper(II) ions are reduced.

Oxidation numbers sum to zero in a neutral compound and to the ion charge in a polyatomic ion. Oxygen is usually −2, with exceptions such as peroxides. Use the rules to track changes and balance transferred electrons before checking atoms and charge.

Work through an example

Find the oxidation number of sulfur in SO₄²⁻.

Explanation: Let sulfur be x: x+4(−2)=−2, so x=+6.

Watch out: The oxidising agent is itself reduced.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

In Zn → Zn²⁺ + 2e⁻, zinc undergoes

  1. Reduction
  2. Oxidation
  3. Condensation
  4. Neutralisation
Show answer and explanation

Answer B: Oxidation

Zinc loses electrons and its oxidation number increases.

Question 2

The oxidation number of manganese in MnO₄⁻ is

  1. +4
  2. +2
  3. +7
  4. +6
Show answer and explanation

Answer C: +7

x+4(−2)=−1 gives x=+7.

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12 Physical chemistry

Electrolysis, cells and corrosion

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What you should be able to do

  • Predict electrode processes
  • Apply charge calculations and corrosion principles

Understand it

Electrolysis uses electrical energy to drive a non-spontaneous reaction. Cations move towards the cathode, where reduction occurs; anions move towards the anode, where oxidation occurs. Products depend on electrolyte, concentration and electrode material.

Charge passed is Q=It. Faraday’s relationship links deposited amount to electron transfer: one mole of electrons carries about 96,485 C. A divalent ion requires two moles of electrons for one mole of metal deposition.

A galvanic cell produces current from a spontaneous redox reaction. Rusting is an electrochemical process involving iron, water and oxygen. Barrier coatings exclude reactants, while sacrificial protection couples iron to a more readily oxidised metal.

Work through an example

How much charge passes when a current of 2 A flows for 5 minutes?

Explanation: Time=300 s. Q=2×300=600 C.

Watch out: Cathode means reduction in both electrolytic and galvanic cells; its sign depends on the cell type.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

At the cathode, ions or molecules undergo

  1. Oxidation
  2. Reduction
  3. Neutralisation
  4. Evaporation
Show answer and explanation

Answer B: Reduction

The cathode supplies electrons for reduction.

Question 2

Which metal can provide sacrificial protection for iron?

  1. Magnesium
  2. Silver
  3. Gold
  4. Copper
Show answer and explanation

Answer A: Magnesium

Magnesium is more readily oxidised and can protect the iron.

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13 Physical chemistry

Energy changes, entropy and feasibility

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What you should be able to do

  • Interpret enthalpy signs
  • Relate enthalpy and entropy to Gibbs energy

Understand it

An exothermic process releases heat to the surroundings and has negative enthalpy change under the usual convention. An endothermic process absorbs heat and has positive enthalpy change. Bond breaking requires energy; bond formation releases it.

Entropy describes the dispersal of energy and the number of accessible microscopic arrangements. Gases usually have greater molar entropy than the corresponding liquids or solids. Mixing gases often increases entropy, although each process must be considered as a whole.

At constant temperature and pressure, ΔG=ΔH−TΔS predicts thermodynamic direction: negative ΔG favours the forward process. At equilibrium ΔG=0; standard ΔG° need not be zero unless the equilibrium constant is 1. Thermodynamic favourability does not guarantee a fast reaction.

Work through an example

If ΔH=−40 kJ mol⁻¹ and TΔS=+10 kJ mol⁻¹, find ΔG.

Explanation: ΔG=−40−10=−50 kJ mol⁻¹.

Watch out: A spontaneous reaction may still be slow because its activation barrier is high.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

For an exothermic reaction, ΔH is usually

  1. Negative
  2. The same sign as temperature in Celsius
  3. Zero
  4. Positive
Show answer and explanation

Answer A: Negative

Heat leaves the reacting system, so its enthalpy decreases.

Question 2

Breaking a chemical bond generally

  1. Has no energy requirement
  2. Requires energy only in ionic compounds
  3. Requires energy
  4. Releases energy
Show answer and explanation

Answer C: Requires energy

Energy is needed to overcome the attractive bonding interaction.

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14 Physical chemistry

Rates of reaction

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What you should be able to do

  • Explain collision theory and rate factors
  • Interpret rate measurements and catalysts

Understand it

Reaction rate measures change in reactant or product amount per unit time. A concentration-time graph is steeper where the reaction is faster. Comparing experiments requires control of other relevant variables.

Particles must collide with suitable orientation and enough energy to react. Higher temperature generally increases the fraction exceeding activation energy. Higher concentration or gas pressure can increase collision frequency, while smaller solid pieces expose more surface area.

A catalyst offers a pathway with lower activation energy and is regenerated overall. It speeds both directions of a reversible reaction without changing the equilibrium constant at the same temperature. Light initiates or accelerates some reactions by supplying energy.

Work through an example

Why does powdered calcium carbonate react faster than an equal mass of large chips with the same acid?

Explanation: The powder has a larger exposed surface area, allowing more reacting contacts per second.

Watch out: A catalyst does not increase the final equilibrium yield merely by speeding the reaction.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which change usually increases reaction rate?

  1. Higher temperature
  2. Smaller exposed surface
  3. Removing a catalyst
  4. Lower temperature
Show answer and explanation

Answer A: Higher temperature

More particles have energy above the activation barrier.

Question 2

A catalyst mainly lowers the

  1. Equilibrium constant at fixed temperature
  2. Enthalpy of the products
  3. Enthalpy of the reactants
  4. Activation energy
Show answer and explanation

Answer D: Activation energy

It provides an alternative reaction pathway with a lower barrier.

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15 Physical chemistry

Chemical equilibrium

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What you should be able to do

  • Explain dynamic equilibrium
  • Predict shifts caused by changed conditions

Understand it

In a closed system, a reversible reaction can reach dynamic equilibrium when forward and reverse rates are equal. Reactant and product concentrations then remain constant, although individual reactions continue.

Le Chatelier’s principle predicts the response to a disturbance. Adding a reactant often favours its consumption. Increasing pressure favours the side with fewer gas moles, when gas amounts differ. Changing temperature favours the direction that absorbs the added heat.

A catalyst changes the speed of reaching equilibrium but not its position at fixed temperature. The equilibrium constant reflects the relative activities or concentrations in an appropriate expression and changes with temperature, not merely with adding more starting material.

Work through an example

For N₂+3H₂ ⇌ 2NH₃, what is the effect of higher pressure at constant temperature?

Explanation: It favours ammonia formation because the product side has fewer gas moles: 2 instead of 4.

Watch out: At equilibrium the concentrations are constant, not necessarily equal.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

At dynamic equilibrium

  1. All reactants disappear
  2. Both reactions stop
  3. Forward and reverse rates are equal
  4. All concentrations are equal
Show answer and explanation

Answer C: Forward and reverse rates are equal

Equal opposing rates produce no net concentration change.

Question 2

Adding a catalyst to an equilibrium mixture at the same temperature

  1. Always increases product yield
  2. Always decreases product yield
  3. Changes the equilibrium constant
  4. Does not shift equilibrium
Show answer and explanation

Answer D: Does not shift equilibrium

Both forward and reverse pathways are accelerated.

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16 Inorganic chemistry

Hydrogen, halogens and chlorides

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What you should be able to do

  • Compare hydrogen and halogen properties
  • Identify simple gas and chloride tests

Understand it

Hydrogen is a light diatomic gas that forms water when burned in oxygen. It can act as a reducing agent and is an important industrial feedstock. In school qualitative testing, a small sample gives a characteristic pop with a flame; practical work requires supervised laboratory procedures.

Halogens are reactive non-metals forming halide ions. Chlorine can oxidise less reactive halide ions such as bromide and iodide. Its uses include controlled water disinfection and manufacture of many chemicals; it is a hazardous gas.

Hydrogen chloride gas dissolves in water to form hydrochloric acid. A chloride test commonly uses acidified silver nitrate to form a white silver chloride precipitate. A gas’s chemistry can differ from that of its aqueous solution.

Work through an example

Why can chlorine displace bromine from a bromide solution?

Explanation: Chlorine is the stronger oxidising agent and converts bromide ions to bromine while itself becoming chloride ions.

Watch out: Hydrogen chloride and hydrochloric acid refer to different physical forms.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Hydrogen burns in oxygen to form

  1. Sodium chloride
  2. Carbon dioxide
  3. Water
  4. Ammonia
Show answer and explanation

Answer C: Water

Hydrogen supplies H and oxygen supplies O in water.

Question 2

Chloride ions with acidified silver nitrate form a

  1. Cream precipitate
  2. Yellow precipitate
  3. Brown precipitate
  4. White precipitate
Show answer and explanation

Answer D: White precipitate

The precipitate is silver chloride.

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17 Inorganic chemistry

Oxygen, water and hardness

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What you should be able to do

  • Compare oxides and oxygen allotropes
  • Explain water hardness and crystal-water changes

Understand it

Oxygen supports many combustion reactions. Ozone is a different molecular form of the same element, containing three oxygen atoms per molecule rather than two. Acidic, basic, amphoteric and neutral oxides differ in their reactions with acids and bases.

Hard water contains appreciable dissolved calcium or magnesium ions and forms scum with soap. Temporary hardness associated with hydrogencarbonates can be reduced by boiling; permanent hardness requires another method, such as ion exchange.

Water of crystallisation is incorporated in a crystal structure. Efflorescent solids lose crystal water to air; hygroscopic substances absorb moisture; deliquescent substances absorb enough water to dissolve. These behaviours must not be confused with ordinary melting.

Work through an example

Why does soap lather poorly in hard water?

Explanation: Calcium and magnesium ions form insoluble salts with soap, using up soap and producing scum.

Watch out: Boiling does not remove every form of water hardness.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

An oxide reacting with both acids and bases is

  1. Amphoteric
  2. Neutral
  3. Acidic only
  4. Basic only
Show answer and explanation

Answer A: Amphoteric

Amphoteric oxides show both types of reaction.

Question 2

A solid that absorbs moisture until it forms a solution is

  1. Inert
  2. Efflorescent
  3. Deliquescent
  4. Sublimed
Show answer and explanation

Answer C: Deliquescent

Deliquescence includes enough absorption to dissolve the substance.

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18 Inorganic chemistry

Sulfur and its compounds

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What you should be able to do

  • Distinguish sulfur oxides and oxidation states
  • Explain major reactions and industrial uses

Understand it

Sulfur occurs in different allotropes, including rhombic and monoclinic forms. Sulfur dioxide is an acidic oxide and commonly acts as a reducing agent. Sulfites release sulfur dioxide on reaction with suitable acids.

The Contact process makes sulfuric acid through oxidation of sulfur dioxide to sulfur trioxide followed by suitable absorption and dilution stages. Catalysis, temperature and contact conditions balance rate and equilibrium yield.

Dilute sulfuric acid shows ordinary acid reactions, while concentrated sulfuric acid can also act as a dehydrating and oxidising agent. Sulfate ions give a white precipitate with a suitable barium reagent under acidic conditions. Sulfide and sulfite tests differ from sulfate tests.

Work through an example

What is the oxidation state of sulfur in SO₂?

Explanation: Each oxygen is usually −2, so sulfur is +4 to make the neutral molecule total zero.

Watch out: Sulfur dioxide and sulfur trioxide are different compounds with different oxidation states.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Sulfur dioxide is generally classified as an

  1. Amphoteric oxide
  2. Basic oxide
  3. Acidic oxide
  4. Neutral oxide
Show answer and explanation

Answer C: Acidic oxide

It forms acidic species in water and reacts with bases.

Question 2

A positive sulfate test commonly forms

  1. Hydrogen gas
  2. Sodium metal
  3. Copper oxide
  4. Barium sulfate
Show answer and explanation

Answer D: Barium sulfate

Barium sulfate is an insoluble white precipitate.

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19 Inorganic chemistry

Nitrogen, ammonia and nitrates

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What you should be able to do

  • Relate nitrogen compounds to industrial processes
  • Identify ammonia and nitrogen-cycle changes

Understand it

Nitrogen gas is relatively unreactive under many ordinary conditions because breaking its triple bond requires much energy. The Haber process combines nitrogen and hydrogen reversibly to make ammonia, using a catalyst and conditions chosen for useful yield and rate.

Ammonia is a basic gas and forms ammonium salts with acids. Ammonium salts release ammonia when warmed with a suitable alkali in a supervised test. Nitric acid production industrially uses oxidation of ammonia in the Ostwald process.

Nitrates are important fertiliser components but excess runoff can harm water systems. Nitrogen fixation, assimilation, decomposition, nitrification and denitrification move nitrogen among air, soil and organisms. Thermal decomposition patterns of nitrates depend on the metal involved.

Work through an example

Write the balanced ammonia formation equation.

Explanation: N₂ + 3H₂ ⇌ 2NH₃. There are two nitrogen atoms and six hydrogen atoms on each side.

Watch out: The Haber process makes ammonia; the Contact process makes sulfuric acid.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Ammonia turns damp red litmus

  1. Unchanged because it is acidic
  2. White
  3. Black
  4. Blue
Show answer and explanation

Answer D: Blue

Ammonia produces an alkaline solution in moisture.

Question 2

The main reactants in the Haber process are

  1. Nitrogen and hydrogen
  2. Carbon and steam only
  3. Nitrogen and oxygen
  4. Sulfur and oxygen
Show answer and explanation

Answer A: Nitrogen and hydrogen

Their reaction produces ammonia.

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20 Inorganic chemistry

Carbon, its oxides and fuels

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What you should be able to do

  • Compare carbon allotropes and oxides
  • Explain fuel processing and carbonate reactions

Understand it

Diamond and graphite contain only carbon but have different structures. Diamond has a three-dimensional covalent network; graphite has layered bonding with mobile electrons, explaining its electrical conduction and easy cleavage between layers.

Complete combustion of carbon forms carbon dioxide; insufficient oxygen can form carbon monoxide. Carbon dioxide turns limewater milky through calcium carbonate formation. Carbon monoxide is a reducing agent and a poisonous gas.

Carbonates react with acids to release carbon dioxide, although their thermal stability varies. Coal processing can yield coke and other products; coke is useful as fuel and reducing material. Synthesis gas is mainly a mixture of carbon monoxide and hydrogen used as chemical feedstock.

Work through an example

Why does graphite conduct electricity while diamond is an insulator?

Explanation: Graphite has electrons able to move within its layered structure; diamond’s valence electrons are localised in its covalent network.

Watch out: Different allotropes are forms of one element, not mixtures of different elements.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A gas turning limewater milky is usually

  1. Helium
  2. Carbon dioxide
  3. Nitrogen
  4. Hydrogen
Show answer and explanation

Answer B: Carbon dioxide

It forms suspended calcium carbonate.

Question 2

Which condition favours carbon monoxide formation from carbon fuels?

  1. The removal of all fuel before ignition
  2. Insufficient oxygen
  3. A fuel containing hydrogen but no carbon
  4. Complete combustion in excess oxygen
Show answer and explanation

Answer B: Insufficient oxygen

Incomplete combustion can leave carbon partly oxidised as CO.

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21 Inorganic chemistry

Reactive metals, extraction and compounds

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What you should be able to do

  • Relate extraction method to reactivity
  • Explain important sodium, calcium and aluminium compounds

Understand it

Metals commonly conduct electricity, lose electrons and form positive ions. Extraction depends on reactivity: very reactive metals usually need electrolysis of suitable molten compounds, while less reactive metal oxides may be reduced chemically.

Sodium compounds include sodium hydroxide, sodium carbonate and sodium hydrogencarbonate. They have different acid-base behaviour and uses. Calcium carbonate decomposes on heating to calcium oxide and carbon dioxide; calcium oxide reacts with water to make calcium hydroxide.

Aluminium is extracted electrolytically from purified alumina dissolved in molten cryolite. Its oxide film helps resist further corrosion. Aluminium oxide and hydroxide are amphoteric. Selecting a material requires considering strength, density, corrosion resistance and cost, not merely metallic appearance.

Work through an example

Why is aluminium not normally extracted by reducing its oxide with carbon?

Explanation: Aluminium has a strong affinity for oxygen, making ordinary carbon reduction unsuitable; electrolysis is used instead.

Watch out: A more reactive metal is not automatically easier to extract from its compound.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Heating calcium carbonate strongly produces

  1. NaOH and H₂
  2. Ca and O₂ only
  3. CaO and CO₂
  4. CaCl₂ and water
Show answer and explanation

Answer C: CaO and CO₂

CaCO₃ → CaO + CO₂.

Question 2

Aluminium is protected from rapid corrosion mainly by

  1. Containing no electrons
  2. A surface oxide film
  3. Dissolving in air
  4. Being a noble gas
Show answer and explanation

Answer B: A surface oxide film

A thin adherent oxide layer limits further attack.

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22 Inorganic chemistry

Transition metals, iron, copper and alloys

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What you should be able to do

  • Recognise transition-metal properties
  • Connect alloy composition to uses

Understand it

Many transition metals show variable oxidation states, coloured compounds, complex-ion formation and catalytic activity. These features relate to their electronic structures, although not every ion or compound is coloured.

Iron can be extracted from suitable ores using reduction in a blast furnace. Steel properties depend on carbon and other additions. Copper can be obtained from ores and refined electrolytically; its high electrical conductivity makes it valuable for wiring. Tin is useful in coatings and alloys.

Alloys are mixtures involving metals and sometimes non-metals. Brass is mainly copper and zinc; bronze is mainly copper and tin; stainless steels contain chromium. Alloying changes how atoms are arranged and can improve hardness, strength or corrosion resistance.

Work through an example

Why is steel often stronger than pure iron?

Explanation: Added atoms disrupt regular layers and hinder their movement, altering the mechanical properties. The exact effect depends on composition and treatment.

Watch out: An alloy does not have the fixed elemental ratio required of a single pure compound.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Brass is mainly an alloy of

  1. Iron and carbon
  2. Copper and zinc
  3. Copper and tin
  4. Aluminium and magnesium
Show answer and explanation

Answer B: Copper and zinc

Copper and zinc are the main brass components.

Question 2

A common transition-metal property is

  1. No catalytic activity
  2. Always colourless compounds
  3. Variable oxidation states
  4. Never forming ions
Show answer and explanation

Answer C: Variable oxidation states

Many transition metals have several accessible oxidation states.

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23 Organic chemistry

Organic formulae, isomerism and hydrocarbons

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What you should be able to do

  • Recognise homologous series and functional groups
  • Compare alkane, alkene, alkyne and aromatic reactions

Understand it

Carbon commonly forms four covalent bonds and can make chains and rings. A homologous series shares a functional group and general pattern, with successive members often differing by CH₂. Structural isomers share a molecular formula but differ in connectivity.

Acyclic alkanes are saturated and have formula CₙH₂ₙ₊₂. Acyclic alkenes with one C=C and no other multiple bonds have CₙH₂ₙ; acyclic alkynes with one C≡C and no other multiple bonds have CₙH₂ₙ₋₂. Unsaturation allows addition reactions, while alkanes commonly undergo substitution under suitable conditions.

Benzene is aromatic and has delocalised bonding around a ring. It does not behave simply like three isolated carbon-carbon double bonds. Geometric isomerism requires restricted rotation and suitable different groups on each carbon of a double bond.

Work through an example

Give the molecular formula of an acyclic alkane with four carbon atoms.

Explanation: CₙH₂ₙ₊₂ gives C₄H₁₀. It has two structural isomers: butane and 2-methylpropane.

Watch out: The formula CₙH₂ₙ alone does not prove an unknown is an alkene; cycloalkanes can share it.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which hydrocarbon contains a carbon-carbon triple bond?

  1. Ethyne
  2. Ethene
  3. Methane
  4. Ethane
Show answer and explanation

Answer A: Ethyne

Ethyne is the simplest alkyne.

Question 2

Structural isomers have the same

  1. Structural formula
  2. Connectivity
  3. IUPAC name
  4. Molecular formula
Show answer and explanation

Answer D: Molecular formula

Their atom counts match, but their structures differ.

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24 Organic chemistry

Petroleum, cracking and petrochemicals

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What you should be able to do

  • Explain petroleum fractionation and conversion
  • Distinguish octane rating from energy content

Understand it

Crude oil is a mixture of hydrocarbons. Fractional distillation separates broad fractions by boiling range rather than making each fraction a single pure substance. Smaller molecules tend to boil at lower temperatures than larger molecules of similar structure.

Cracking breaks larger hydrocarbon molecules into smaller ones, often producing both alkanes and alkenes. Reforming rearranges structures to improve fuel characteristics or create useful chemical feedstocks. Petrochemicals support manufacture of polymers, solvents and other products.

Octane rating describes resistance to engine knocking under standardised comparison conditions. It is not simply the percentage of octane in every fuel, nor a direct measure of energy per litre. Fuel choice also involves engine design, emissions and safe handling.

Work through an example

What useful reaction class allows a large alkane to supply an alkene for plastic manufacture?

Explanation: Cracking can split a larger hydrocarbon into smaller molecules, including alkenes used as monomers.

Watch out: Fractional distillation separates existing molecules; cracking changes molecules chemically.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Crude-oil fractions are separated mainly by differences in

  1. Electrical conductivity
  2. Boiling range
  3. Solubility in water
  4. Magnetic attraction
Show answer and explanation

Answer B: Boiling range

Different fractions vaporise and condense at different temperature ranges.

Question 2

Cracking mainly involves

  1. Breaking larger hydrocarbons into smaller ones
  2. Adding hydrogen across every double bond
  3. Joining small alkenes into long polymer chains
  4. Separating fractions without chemical change
Show answer and explanation

Answer A: Breaking larger hydrocarbons into smaller ones

It converts less useful large molecules to smaller products.

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25 Organic chemistry

Alcohols, carbonyls, acids, esters and amines

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What you should be able to do

  • Identify common functional groups
  • Predict simple transformations and distinguish compound classes

Understand it

Alcohols contain an −OH group attached to saturated carbon. Primary alcohols can oxidise to aldehydes and then carboxylic acids; secondary alcohols form ketones. Ordinary mild oxidation does not treat tertiary alcohols the same way. The Lucas test distinguishes classes by substitution behaviour, not by being an oxidation test.

Aldehydes and ketones contain a carbonyl group but differ in its position and attached groups. Carboxylic acids contain −COOH and react with bases. Esterification combines an alcohol and carboxylic acid reversibly to form an ester and water.

Amines are related to ammonia by replacement of hydrogen with carbon-containing groups and commonly show basic behaviour. Fats and oils are esters of glycerol and fatty acids. Alkaline hydrolysis of suitable fats yields glycerol and soap; hydrogenation can make oils more saturated.

Work through an example

Name the ester formed from ethanol and ethanoic acid.

Explanation: Ethyl ethanoate forms, along with water. The alcohol supplies the ethyl part and the acid the ethanoate part.

Watch out: An ester name lists the alcohol-derived alkyl group before the acid-derived part.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Oxidation of a secondary alcohol generally gives a

  1. Noble gas
  2. Metal
  3. Ketone
  4. Primary amine
Show answer and explanation

Answer C: Ketone

The carbon bearing OH becomes a carbonyl carbon bonded to two carbon groups.

Question 2

The functional group −COOH identifies a

  1. Alkane
  2. Carboxylic acid
  3. Amine
  4. Alkene
Show answer and explanation

Answer B: Carboxylic acid

It combines carbonyl and hydroxyl features in the carboxyl group.

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26 Organic chemistry

Carbohydrates, proteins and polymers

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What you should be able to do

  • Classify biological molecules and tests
  • Compare polymerisation and plastic behaviour

Understand it

Monosaccharides are simple sugars; disaccharides contain two linked sugar units; polysaccharides contain many. Hydrolysis breaks larger carbohydrates into smaller units. Reducing sugars react in tests such as Benedict’s, while starch gives a blue-black iodine result.

Proteins are amino-acid polymers joined by peptide bonds. Hydrolysis releases smaller peptides or amino acids. The Biuret test detects peptide bonds. Enzymes are biological catalysts with activity affected by temperature, pH and other conditions.

Addition polymerisation links suitable unsaturated monomers without releasing a small molecule. Condensation polymerisation commonly forms links while releasing small molecules. Thermoplastics can soften repeatedly on heating; thermosetting materials form cross-linked structures that do not remelt in the same way. Vulcanisation introduces cross-links into rubber.

Work through an example

Why is poly(ethene) an addition polymer?

Explanation: Ethene molecules join as their double bonds open, forming a chain without eliminating a small molecule at each link.

Watch out: A natural polymer and a synthetic polymer can have very different properties; polymer does not mean plastic only.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Proteins are built from

  1. Monosaccharides
  2. Nucleotides
  3. Amino acids
  4. Fatty acids and glycerol
Show answer and explanation

Answer C: Amino acids

Amino acids link through peptide bonds.

Question 2

Which material can usually be softened repeatedly by heating?

  1. Fully cured epoxy resin
  2. Thermoplastic
  3. Cross-linked phenol-formaldehyde resin
  4. Fully cured thermoset
Show answer and explanation

Answer B: Thermoplastic

Thermoplastics generally lack the permanent cross-linking of thermosets.

Link to this topic

27 Applied chemistry

Chemical industries and biotechnology

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What you should be able to do

  • Connect raw materials, processes and useful products
  • Explain waste control and biological production

Understand it

Chemical industries convert raw materials into products such as fertilisers, cement, glass, soap, medicines and polymers. A process must be evaluated for yield, purity, energy needs, cost and environmental effects.

Cement production uses mineral raw materials and high-temperature processing; glass manufacture uses silica with additives; soap manufacture uses suitable oils or fats and alkali. The same raw material can supply different industries through different reaction routes.

Biotechnology uses organisms or their enzymes in production. Fermentation can produce foods, ethanol and other chemicals under controlled conditions. Industrial control of temperature, pH and contamination improves consistency, while recovery and treatment of waste reduce environmental harm.

Work through an example

Why does an industrial fermenter need temperature control?

Explanation: Too low a temperature can slow microbial activity, while excessive heat can damage cells or enzymes and reduce useful production.

Watch out: A high reaction yield alone does not make an industrial process economically or environmentally suitable.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Silica is a major raw material in the manufacture of

  1. Glass
  2. Ammonia
  3. Soap
  4. Polyethene
Show answer and explanation

Answer A: Glass

Silica forms the main network of common glass.

Question 2

Using microbes to make ethanol is an example of

  1. Biotechnology
  2. Cracking
  3. Fractional distillation
  4. Hydration of ethene without microbes
Show answer and explanation

Answer A: Biotechnology

A biological process is used to make a useful chemical.

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28 Applied chemistry

Astronomical chemistry and Earth systems

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What you should be able to do

  • Identify the broad structure of the Solar System
  • Distinguish atmosphere, hydrosphere and lithosphere

Understand it

The Solar System includes the Sun, eight planets and many smaller bodies. The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A natural satellite orbits a larger body; Earth’s Moon is one example.

The inner planets are mainly rocky, while the outer giant planets have different compositions and structures. Pluto is classified as a dwarf planet rather than one of the eight planets. Planet and satellite are different categories.

Earth’s atmosphere is its gaseous envelope; the hydrosphere includes its water; the lithosphere is its rigid outer rocky layer. Chemical elements move between Earth systems through processes such as weathering, gas exchange and biological activity.

Work through an example

Classify ocean water, air and surface rock by Earth system.

Explanation: Ocean water belongs to the hydrosphere, air to the atmosphere and the rigid rocky outer layer to the lithosphere.

Watch out: The Solar System is not the same thing as the Milky Way galaxy.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which planet lies between Earth and Jupiter?

  1. Saturn
  2. Venus
  3. Neptune
  4. Mars
Show answer and explanation

Answer D: Mars

The order is Earth, Mars, Jupiter.

Question 2

The hydrosphere refers to Earth’s

  1. Water
  2. Solid rocks only
  3. Living organisms only
  4. Gases around the planet only
Show answer and explanation

Answer A: Water

It includes water in its major forms and reservoirs.

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Scope checked against JAMB’s IBASS source on 2026-10-16. Current IBASS file; not independently labelled 2027. Notes, examples and practice questions are original CampusNinja learning material, not authenticated JAMB past questions.

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