JAMB Chemistry practice: free CBT questions with answers
UTME Chemistry covers separation techniques, gas laws and kinetic theory, atomic structure and the periodic table, bonding, the mole concept and stoichiometry, acids, bases and salts, redox and electrolysis, energy, rates and equilibrium, metals and non-metals, organic chemistry and Nigeria's petroleum industry.
In the UTME CBT, Chemistry is one of your three subjects besides Use of English: 40 questions, inside a 2-hour paper of 180 questions scored out of 400.
CrackIt has 454 original Chemistry questions across 22 syllabus topics (149 easy, 207 medium, 98 hard), each with an explanation in English and Pidgin.
5 free JAMB Chemistry practice questions
Original questions from our bank, written to the syllabus. Tap “Show answer” to check yourself.
Q1. Separation of mixtures and purification
During the laboratory preparation of dry oxygen gas using potassium chlorate, manganese(IV) oxide is added and the gas is collected over water. Which separation method is primarily used to remove water vapor from the collected oxygen?
- AFiltering the gas through filter paper
- BUsing a separating funnel
- CFreezing the gas mixture to -20° C
- DPassing the gas through concentrated tetraoxosulphate(VI) acid
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Answer: D. Passing the gas through concentrated tetraoxosulphate(VI) acid
Concentrated tetraoxosulphate(VI) acid is a powerful drying agent that absorbs moisture from gases bubbled through it. It is commonly used to dry gases that do not react with acid, such as oxygen.
Pidgin: Concentrated tetraoxosulphate(VI) acid na strong drying agent wey dey suck water commot from gas when you pass am inside. Na him people dey use dry gas like oxygen wey no dey react with acid.
Q2. Atomic structure, isotopes and electron configuration
Which statement best describes isotopes of the same element?
- AThey have the same mass number but different atomic numbers
- BThey have the same chemical properties due to the same number of electrons
- CThey have different numbers of valence electrons
- DThey have different numbers of protons and neutrons
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Answer: B. They have the same chemical properties due to the same number of electrons
Isotopes have the same atomic number and number of electrons, leading to identical chemical properties, but differ in the number of neutrons and hence mass numbers.
Pidgin: Isotopes na same element wey get same number of electrons, na why their chemical behavior dey same. Na only their number of neutrons dey different.
Q3. Stoichiometry and the mole concept
What volume does 2.2 g of carbon dioxide gas, CO₂, occupy at standard temperature and pressure (STP)? [Molar volume at STP = 22.4 dm³, C = 12, O = 16]
- A1.12 dm³
- B11.20 dm³
- C2.24 dm³
- D22.40 dm³
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Answer: A. 1.12 dm³
Molar mass of CO₂ is 12 + (16 x 2) = 44 g/mol. Number of moles = 2.2 g / 44 g/mol = 0.05 mol. Volume = 0.05 mol x 22.4 dm³/mol = 1.12 dm³.
Pidgin: First find mole of CO₂ by dividing mass 2.2 by molar mass 44, e give 0.05 mol. Then multiply by molar volume 22.4 to get 1.12 dm³.
Q4. Oxidation and reduction, oxidation numbers
Which of the following chemical species acts strictly as a reducing agent in redox reactions?
- AH₂S
- BKMnO₄
- CSO₂
- DH₂O₂
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Answer: A. H₂S
H₂S contains sulphur in its lowest oxidation state of -2, meaning it can only be oxidized to higher states and thus acts solely as a reducing agent.
Pidgin: H₂S get sulphur wey dey im lowest oxidation state of -2, e mean say na only oxidation e fit undergo, so e dey act like reducing agent.
Q5. Energy changes in reactions
What is the primary effect of adding a positive catalyst to a reversible exothermic reaction?
- AIt increases the yield of the products at equilibrium
- BIt decreases the enthalpy change of the forward reaction
- CIt lowers the activation energy for both forward and reverse reactions
- DIt increases the potential energy of the reactants
Show answer
Answer: C. It lowers the activation energy for both forward and reverse reactions
A catalyst provides an alternative reaction pathway with a lower activation energy for both the forward and reverse reactions. It does not alter the enthalpy change or the position of equilibrium.
Pidgin: Catalyst work na to reduce activation energy for both going front and coming back. E no dey change heat change (delta H) or how much product you go get.
Topics covered
- Separation of mixtures and purification (23)
- Kinetic theory and gas laws (21)
- Atomic structure, isotopes and electron configuration (18)
- Periodic table and periodicity (21)
- Chemical bonding (21)
- Stoichiometry and the mole concept (23)
- Acids, bases and salts, pH (25)
- Oxidation and reduction, oxidation numbers (19)
- Electrolysis and Faraday's laws (23)
- Energy changes in reactions (26)
- Rates of reaction (24)
- Chemical equilibrium and Le Chatelier's principle (23)
- Water, hardness of water and solubility (26)
- Air and environmental pollution (26)
- Non-metals: hydrogen, oxygen, nitrogen, sulphur, chlorine and their compounds (19)
- Metals and their extraction, alloys (20)
- Organic chemistry: hydrocarbons (24)
- Organic chemistry: alcohols, carboxylic acids, esters, fats and soaps (17)
- Polymers, petroleum and crude oil refining in Nigeria (14)
- Nuclear chemistry and radioactivity (22)
- Carbon and its compounds (5)
- Fats, oils, soaps and food chemistry (14)
How to score higher in Chemistry
- The mole concept sits behind many calculation questions. Get comfortable converting between mass, moles, volume of gas and number of particles.
- Electrolysis and Faraday's laws, and Le Chatelier's principle, are favourite topics. Practise both the calculations and the reasoning.
- For organic chemistry, learn the functional groups and their typical reactions as a table you can picture.
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Frequently asked questions
How many questions are in JAMB UTME Chemistry?
In the UTME CBT, Chemistry is one of your three subjects besides Use of English: 40 questions, inside a 2-hour paper of 180 questions scored out of 400.
Are these real past questions?
No. CrackIt's 454 Chemistry questions are original, written to the official JAMB syllabus, and each has a worked explanation. CrackIt is not affiliated with JAMB, WAEC or NECO.
Is CrackIt free and does it work offline?
Yes. Practice by topic, timed tests and the Daily 10 are free, and once the app has loaded it works without data.
Can I read the explanations in Pidgin?
Yes. Every Chemistry explanations have a Pidgin version: tap “Pidgin” under the answer.