JAMB Chemistry Questions and Answers 2026/2027 | How to Pass JAMB Chemistry | JAMB Chemistry Syllabus Topics | Chemistry Likely Questions for JAMB UTME
Introduction: How to Ace JAMB Chemistry in 2026/2027
Chemistry is a subject that connects the physical and biological sciences. For JAMB 2026/2027 candidates targeting Medicine, Pharmacy, Biochemistry, Microbiology, Chemical Engineering, or any natural science program, Chemistry is both compulsory and pivotal. A strong Chemistry score can be the difference between admission and missing your cut-off mark.
JAMB Chemistry covers a wide range of topics from atomic structure and the periodic table to organic chemistry, electrochemistry, thermodynamics, and chemical kinetics. The subject is roughly 40% theoretical and 60% requiring you to apply concepts, balance equations, and solve mole calculations. This balance makes strategic preparation essential.
The 50 questions in this section are drawn from the most-tested areas of the JAMB Chemistry syllabus, with special attention to topics JAMB has repeatedly tested between 2018 and 2025. Each answer is designed to teach you not just what the answer is, but why it is correct.
JAMB Chemistry Syllabus Overview
The JAMB Chemistry syllabus is organized into: Separation and Purification techniques, Kinetic Theory and States of Matter, Atomic Structure and Periodic Table, Chemical Bonding, Acids/Bases/Salts, Electrochemistry, Energy Changes, Rates of Reaction, Equilibria, Non-metals (Carbon, Nitrogen, Sulfur, Halogens), Metals and their Compounds, Organic Chemistry (hydrocarbons, functional groups, polymers), and Environmental/Industrial Chemistry. Organic Chemistry alone can account for up to 30% of the exam.
50 Predicted JAMB 2026/2027 Chemistry Questions and Answers
Q1. What is the periodic law?
Answer: The properties of elements are a periodic function of their atomic numbers. When elements are arranged in order of increasing atomic number, similar properties recur at regular intervals.
Q2. Define ‘electronegativity’.
Answer: The ability of an atom to attract shared electrons toward itself in a chemical bond. Fluorine has the highest electronegativity (4.0 on the Pauling scale).
Q3. What is ‘Avogadro’s Number’?
Answer: Avogadro’s Number is 6.02 x 10²³. It represents the number of atoms, molecules, or ions in one mole of any substance.
Q4. Balance this equation: H₂ + O₂ → H₂O
Answer: 2H₂ + O₂ → 2H₂O. Two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water.
Q5. What is the difference between an ‘atom’ and a ‘molecule’?
Answer: An atom is the smallest unit of an element that retains the chemical properties of that element. A molecule is two or more atoms bonded together, which may be of the same or different elements.
Q6. What is ‘pH’?
Answer: pH is a scale from 0 to 14 that measures how acidic or alkaline a solution is. pH 7 is neutral; below 7 is acidic; above 7 is alkaline (basic).
Q7. Define ‘oxidation’ in terms of electrons.
Answer: Oxidation is the loss of electrons by an atom, ion, or molecule. (OIL: Oxidation Is Loss)
Q8. What is the molar mass of water (H₂O)?
Answer: Molar mass of H₂O = (2 x 1) + 16 = 18 g/mol.
Q9. What is ‘Hess’s Law’?
Answer: The total enthalpy change for a reaction is independent of the pathway taken, as long as the initial and final states are the same.
Q10. What type of bond is formed between Na and Cl in NaCl?
Answer: An ionic bond. Sodium loses one electron to chlorine, resulting in Na⁺ and Cl⁻ ions attracted to each other.
Q11. What is a ‘catalyst’?
Answer: A substance that increases the rate of a chemical reaction without being consumed or permanently altered in the process.
Q12. Define ‘isomerism’.
Answer: Isomers are compounds with the same molecular formula but different structural arrangements or spatial configurations, giving them different properties.
Q13. What is Le Chatelier’s Principle?
Answer: If a system in dynamic equilibrium is disturbed, the system will shift in the direction that minimizes the effect of the disturbance and re-establishes equilibrium.
Q14. What is ‘enthalpy change’ (ΔH)?
Answer: The heat energy absorbed or released during a chemical reaction at constant pressure. Negative ΔH indicates an exothermic reaction; positive ΔH indicates an endothermic reaction.
Q15. Calculate the number of moles in 36 g of water (H₂O). Molar mass = 18 g/mol.
Answer: Moles = mass/molar mass = 36/18 = 2 moles of water.
Q16. What is ‘electrolysis’?
Answer: The process of using an electric current to drive a non-spontaneous chemical reaction, typically the decomposition of an electrolyte into its constituent elements.
Q17. Define ‘hybridization’ in chemistry.
Answer: The mixing of atomic orbitals to form new orbitals (hybrid orbitals) of equal energy and shape, suitable for chemical bonding. Example: sp³ hybridization in methane (CH₄).
Q18. What is ‘Faraday’s First Law of Electrolysis’?
Answer: The mass of a substance deposited or liberated at an electrode is directly proportional to the quantity of electricity (charge) passed through the electrolyte.
Q19. What are ‘allotropes’?
Answer: Different structural forms of the same element that have different physical properties. Example: diamond and graphite are both allotropes of carbon.
Q20. What is the ‘rate of reaction’ and what factors affect it?
Answer: The rate of reaction is the speed at which reactants are converted to products. It is affected by temperature, concentration, surface area, pressure (for gases), and catalysts.
Q21. What is an ‘ester’ and how is it formed?
Answer: An ester is an organic compound formed by the reaction of a carboxylic acid with an alcohol, with water as a byproduct. This process is called esterification.
Q22. Define ’empirical formula’.
Answer: The simplest whole-number ratio of atoms of each element in a compound. Example: the empirical formula of glucose (C₆H₁₂O₆) is CH₂O.
Q23. What is ‘galvanic corrosion’?
Answer: The electrochemical process by which a less noble metal corrodes preferentially when it is in electrical contact with a more noble metal in the presence of an electrolyte.
Q24. What gas is produced when zinc reacts with dilute hydrochloric acid?
Answer: Hydrogen gas (H₂) is produced. Zn + 2HCl → ZnCl₂ + H₂.
Q25. What is ‘Raoult’s Law’?
Answer: The vapor pressure of a solution is directly proportional to the mole fraction of the solvent. It applies to ideal solutions.
Q26. Define ‘saponification’.
Answer: The alkaline hydrolysis of fats or esters to form soap (fatty acid salts) and glycerol. It is the reaction between fat/oil and sodium hydroxide (NaOH).
Q27. What is a ‘buffer solution’?
Answer: A solution that resists significant changes in pH when small amounts of acid or base are added. It consists of a weak acid and its conjugate base (or vice versa).
Q28. What is ‘nuclear fusion’?
Answer: The process in which two light atomic nuclei combine to form a heavier nucleus, releasing enormous amounts of energy. It is the energy source of the sun.
Q29. What is the test for the presence of starch?
Answer: Add iodine solution (iodine in potassium iodide). A blue-black color indicates the presence of starch.
Q30. Define ‘valency’.
Answer: The combining capacity of an element, representing the number of hydrogen atoms (or equivalent) it can combine with or replace. Example: Carbon has a valency of 4.
Q31. What is ‘reduction’ in terms of electrons?
Answer: Reduction is the gain of electrons by an atom, ion, or molecule. (RIG: Reduction Is Gain)
Q32. What is the difference between ‘saturated’ and ‘unsaturated’ hydrocarbons?
Answer: Saturated hydrocarbons (alkanes) contain only single carbon-carbon bonds. Unsaturated hydrocarbons (alkenes and alkynes) contain one or more double or triple bonds.
Q33. What is ‘colligative properties’ of solutions?
Answer: Properties that depend only on the number of solute particles dissolved and not on their chemical nature. Examples: boiling point elevation, freezing point depression, osmotic pressure.
Q34. What is the ‘octet rule’?
Answer: Atoms tend to gain, lose, or share electrons in order to achieve a full outer shell of 8 electrons (like noble gases), resulting in stable configurations.
Q35. Name the functional group of aldehydes.
Answer: Aldehydes contain the carbonyl group (C=O) at the end of a carbon chain, giving the formula R-CHO. Example: methanal (formaldehyde), HCHO.
Q36. What is ‘Charles’s Law’ in chemistry?
Answer: At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature: V/T = constant.
Q37. What is ‘the Common Ion Effect’?
Answer: The decrease in solubility of an ionic compound when a soluble compound containing a common ion is added to the solution, shifting equilibrium toward the solid.
Q38. What is produced when copper(II) sulfate is electrolyzed using inert electrodes?
Answer: At the cathode: copper (Cu) is deposited. At the anode: oxygen (O₂) is produced. CuSO₄ → Cu²⁺ + SO₄²⁻.
Q39. Define ‘activation energy’.
Answer: The minimum amount of energy required for reactant molecules to collide and form products in a chemical reaction.
Q40. What is the difference between ‘homogeneous’ and ‘heterogeneous’ mixtures?
Answer: Homogeneous mixtures have uniform composition throughout (e.g., salt water). Heterogeneous mixtures have non-uniform composition with visibly different components (e.g., sand and water).
Q41. What is ‘Dalton’s Law of Partial Pressures’?
Answer: The total pressure of a mixture of gases equals the sum of the partial pressures of each individual gas, assuming no chemical interaction.
Q42. What is ‘chromatography’ used for?
Answer: Chromatography is used to separate, identify, and analyze mixtures based on the different rates at which components travel through a stationary phase when carried by a mobile phase.
Q43. What is the IUPAC name for CH₃CH₂OH?
Answer: Ethanol (ethyl alcohol). It is also called drinking alcohol. Its molecular formula is C₂H₅OH.
Q44. What is ‘Boyle’s Law’ in chemistry?
Answer: At constant temperature, the pressure of a fixed mass of gas is inversely proportional to its volume: PV = constant. P₁V₁ = P₂V₂.
Q45. Define ‘ionization energy’.
Answer: The minimum energy required to remove one electron from an atom in its gaseous state to form a positive ion (cation). First ionization energy refers to removal of the first electron.
Q46. What is ‘standard enthalpy of formation’?
Answer: The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states at 298 K and 1 atm pressure.
Q47. What is a ‘noble gas’ and why are they unreactive?
Answer: Noble gases (Group 18: He, Ne, Ar, Kr, Xe, Rn) have complete outer electron shells (8 electrons, or 2 for helium), making them extremely stable and chemically inert.
Q48. What is ‘vulcanization’ of rubber?
Answer: The process of treating natural rubber with sulfur at high temperatures to form cross-links between polymer chains, making the rubber stronger, more elastic, and more resistant to heat and chemicals.
Q49. Define ‘fractional distillation’.
Answer: A separation technique used to separate mixtures of liquids with different boiling points by heating and collecting condensed vapors at different temperatures. Used industrially to separate crude oil.
Q50. What is an ‘amphoteric oxide’?
Answer: An oxide that can react with both acids and bases. Example: aluminum oxide (Al₂O₃) reacts with HCl (acid) and NaOH (base).
CBT Tips for JAMB Chemistry
For calculation questions, always write out what is given and what you are looking for before picking your formula. Mole calculation questions are extremely common and follow a predictable pattern: moles = mass/molar mass. Know the periodic table intimately. Know the properties and reactions of key metals (sodium, calcium, iron, copper) and non-metals (carbon, sulfur, chlorine, nitrogen, oxygen). For organic chemistry, know the functional groups and the reactions associated with each class.
Frequently Asked Questions
Q: What are the most tested topics in JAMB Chemistry 2026/2027?
A: Mole calculations, periodic table, atomic structure, chemical bonding, electrolysis, organic chemistry (especially hydrocarbons and functional groups), and equilibrium are consistently the most tested topics in JAMB Chemistry.
Q: How do I quickly solve mole calculation questions in JAMB?
A: Remember three key formulas: Moles = mass/molar mass; Moles = volume (in dm³)/22.4 for gases at STP; Moles = Concentration x Volume (in dm³). Identify which formula to use based on the information given in the question.
Q: Is JAMB Chemistry harder than Physics?
A: Both have different challenges. Chemistry has more memorization (reactions, properties, names) while Physics has more mathematical application. Most students find Chemistry slightly more predictable once they master the mole concept and organic chemistry.
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