2023 JAMB CHEMISTRY PAST QUESTIONS AND ANSWERS Leave a Comment / Jamb Chemistry / By Jamb Tutor Report a question What’s wrong with this question? You cannot submit an empty report. Please add some details. 0% Created by Jamb TutorJamb Chemistry 2023 JAMB CHEMISTRY PAST QUESTIONS AND ANSWERS 1 / 45 Category: JAMB Chemistry 2023 1. What happens to equilibrium position if temperature decreases in an exothermic reaction? a) Stops b) Left c) Right d) Unchanged Equilibrium shifts right to favor heat production. 2 / 45 Category: JAMB Chemistry 2023 2. Which radioactive noble gas forms as uranium and thorium decay? a) Argon b) Krypton c) Radon d) Neon Radon is the noble gas produced during decay. 3 / 45 Category: JAMB Chemistry 2023 3. Reaction with highest entropy change: Liquid → Gas, Solid → Liquid, etc.? a) Liquid to Gas b) Solid to Liquid c) Gas to Liquid d) Gas to Solid Liquid to gas has maximum entropy increase. 4 / 45 Category: JAMB Chemistry 2023 4. Sum of oxidation numbers in neutral compound? a) 2 b) -1 c) 0 d) 1 The total oxidation number for a neutral compound is always 0. 5 / 45 Category: JAMB Chemistry 2023 5. Pressure by gases explained in kinetic theory? a) Vibrations b) Weight of particles c) Attractive forces d) Collisions with walls Pressure arises from collisions with container walls. 6 / 45 Category: JAMB Chemistry 2023 6. Eutrophication definition? a) Harmful chemicals b) Algal growth c) Heavy metals d) Oil slicks Caused by nutrient over-enrichment, leading to algal blooms. 7 / 45 Category: JAMB Chemistry 2023 7. Name of industrial process to produce ammonia? a) Nitrogenation b) Ammoniation c) Nitrification d) Haber process Haber process synthesizes ammonia industrially. 8 / 45 Category: JAMB Chemistry 2023 8. Scientist proposing planetary atomic model? a) Schrödinger b) Rutherford c) Bohr d) Thomson Rutherford introduced the orbiting electrons model. 9 / 45 Category: JAMB Chemistry 2023 9. Example of an endothermic reaction? a) Combustion of propane b) Burning methane c) NaCl formation d) $H_2O_2$ decomposition Decomposition of $H_2O_2$ absorbs energy. 10 / 45 Category: JAMB Chemistry 2023 10. Effect on $K_c$ value when reaction reverses? a) Becomes 0 b) Becomes negative c) Unchanged d) Reciprocal $K_c$ becomes reciprocal of the original value. 11 / 45 Category: JAMB Chemistry 2023 11. Chemical structure of soap/detergent? a) Hydrophilic head, hydrophobic tail b) Hydrophilic head, hydrophilic tail c) Hydrophobic head/tail d) Hydrophilic tail Hydrophilic head attracts water; hydrophobic tail repels it. 12 / 45 Category: JAMB Chemistry 2023 12. Purpose of $K_{sp}$ constant? a) Total mass dissolved b) Solute concentration c) Calculate solubility d) Compare solubility Measures solute concentration in saturated solutions. 13 / 45 Category: JAMB Chemistry 2023 13. Atmospheric trace gas in greenhouse effect? a) Oxygen b) Argon c) Carbon dioxide d) Nitrogen Carbon dioxide is a significant greenhouse gas. 14 / 45 Category: JAMB Chemistry 2023 14. Method to remove temporary water hardness? a) Boiling b) Filtration c) Sedimentation d) Chlorination Boiling removes bicarbonates causing temporary hardness. 15 / 45 Category: JAMB Chemistry 2023 15. Value of Faraday’s constant? a) $6.022 × 10^{23}$ mol$^{-1}$ b) $3.00 × 10^8$ m/s c) 9.81 m/s$^2$ d) 96,485 C/mol One mole of charge: 96,485 C/mol. 16 / 45 Category: JAMB Chemistry 2023 16. Gas volume change with pressure increase? a) 6 liters b) 1.5 liters c) 0.75 liters d) 3 liters Halving the volume doubles the pressure per Boyle’s Law. 17 / 45 Category: JAMB Chemistry 2023 17. Composition of stainless steel alloy? a) Iron and zinc b) Copper and tin c) Iron and chromium d) Iron and carbon Iron alloyed with chromium resists rusting. 18 / 45 Category: JAMB Chemistry 2023 18. State of matter with widely spaced, high-energy particles? a) Liquid b) Solid c) Plasma d) Gas Gas particles exhibit high kinetic energy and freedom. 19 / 45 Category: JAMB Chemistry 2023 19. Reducing agent in reaction: Zn + $CuSO_4$ → $ZnSO_4$ + Cu? a) Cu b) Zn c) $ZnSO_4$ d) $CuSO_4$ Zinc donates electrons, reducing Cu$^{2+}$ to Cu. 20 / 45 Category: JAMB Chemistry 2023 20. Balance $Fe_2O_3$ + CO → Fe + $CO_2$ a) $Fe_2O_3$ + CO → 2Fe + $2CO_2$ b) $2Fe_2O_3$ + 3CO → 4Fe + $3CO_2$ c) $Fe_2O_3$ + 2CO → 2Fe + $2CO_2$ d) $Fe_2O_3$ + 3CO → 2Fe + $3CO_2$ Proper balancing satisfies stoichiometric laws. 21 / 45 Category: JAMB Chemistry 2023 21. Trend of ionization energy across a period? a) Increases left-right b) Constant c) Random variation d) Decreases left-right Ionization energy increases due to effective nuclear charge. 22 / 45 Category: JAMB Chemistry 2023 22. Transfer of electrons forming oppositely charged ions? a) Ionic b) Hydrogen c) Covalent d) Metallic Ionic bonds result from electron transfer between atoms. 23 / 45 Category: JAMB Chemistry 2023 23. Alkane with straight-chain structure? a) Cyclopentane b) Isobutane c) 2-methyl propane d) Pentane Pentane has no branching, qualifying as straight chain. 24 / 45 Category: JAMB Chemistry 2023 24. Products of NaCl electrolysis with inert electrodes? a) $H_2$ at cathode, $Cl_2$ at anode b) $H_2$ at cathode, $O_2$ at anode c) Na metal, $Cl_2$ gas d) Na metal, $O_2$ gas $H_2$ at cathode, $Cl_2$ at anode from NaCl. 25 / 45 Category: JAMB Chemistry 2023 25. Effect of diluting acidic solution on pH? a) Depends on acid b) Decreases c) Remains same d) Increases Dilution reduces H$^+$ ion concentration, increasing pH. 26 / 45 Category: JAMB Chemistry 2023 26. Factor NOT affecting reaction rate? a) Reactant concentration b) Catalyst presence c) Product molecular weight d) Temperature Reaction rate doesn’t depend on product molecular weight. 27 / 45 Category: JAMB Chemistry 2023 27. Organic compound responsible for fruit aroma? a) Alkane b) Alkyne c) Ester d) Amine Esters impart distinct fruity scents. 28 / 45 Category: JAMB Chemistry 2023 28. Molar mass of $H_2O$? a) 18 g/mol b) 22 g/mol c) 16 g/mol d) 12 g/mol $H_2 = 2$ + O = 16, Total: 18 g/mol. 29 / 45 Category: JAMB Chemistry 2023 29. Chemical formula of rust? a) $Fe_3O_4$ b) FeO c) Fe(OH)$_3$ d) $Fe_2O_3$ Rust: $Fe_2O_3·H_2O$ forms with oxygen/moisture. 30 / 45 Category: JAMB Chemistry 2023 30. Number of π bonds in an alkene with 6 carbons? a) 4 b) 6 c) 5 d) 3 One π bond for each double bond in alkenes. 31 / 45 Category: JAMB Chemistry 2023 31. Principal ore of iron? a) Calcite b) Bauxite c) Magnetite d) Hematite Hematite is a major iron ore. 32 / 45 Category: JAMB Chemistry 2023 32. Group of calcium in periodic table? a) Alkaline earth metals b) Halogens c) Alkali metals d) Noble gases Calcium belongs to Alkaline Earth Metals. 33 / 45 Category: JAMB Chemistry 2023 33. Primary constituent of crude oil? a) Pentane b) Ethanol c) Heptane d) Methane Methane is a primary hydrocarbon in crude oil. 34 / 45 Category: JAMB Chemistry 2023 34. Main source of carbon monoxide in urban areas? a) Volcanic eruptions b) Vehicle emissions c) Forest fires d) Industrial processes Vehicle emissions release most CO in cities. 35 / 45 Category: JAMB Chemistry 2023 35. Empirical formula of compound with 40% C, 6.67% H, and 53.33% O? a) $C_4H_8O_4$ b) $CH_2O$ c) $C_2H_4O_2$ d) $C_3H_6O_3$ Simplify ratios to determine $CH_2O$ empirical formula. 36 / 45 Category: JAMB Chemistry 2023 36. True statement about acids? a) All acids strong b) Bitter taste c) Turn litmus red d) pH > 7 Acids turn blue litmus paper red. 37 / 45 Category: JAMB Chemistry 2023 37. Bond formed by electron pair sharing? a) Ionic b) Covalent c) Hydrogen d) Metallic Covalent bonds involve shared electron pairs. 38 / 45 Category: JAMB Chemistry 2023 38. Effect of adding salt to boiling point of water? a) Decreases b) Unchanged c) Increases d) Unpredictable Salt increases water boiling point (boiling point elevation). 39 / 45 Category: JAMB Chemistry 2023 39. Process converting gas to liquid? a) Condensation b) Evaporation c) Sublimation d) Freezing Condensation changes gas phase to liquid. 40 / 45 Category: JAMB Chemistry 2023 40. Example of decomposition reaction? a) $2H_2$ + $O_2$ b) $2H_2O$ to $2H_2$ c) Na + $Cl_2$ d) $CaCO_3$ to CaO + $CO_2$ $CaCO_3$ → CaO + $CO_2$ breaks one compound into simpler products. 41 / 45 Category: JAMB Chemistry 2023 41. Reason for leaf color change during autumn? a) Decreased chlorophyll b) Increased water uptake c) Increased light d) Decreased temperature Decreased chlorophyll production reveals other pigments. 42 / 45 Category: JAMB Chemistry 2023 42. Function of sodium-potassium pump in cells? a) Maintains gradient b) Synthesizes proteins c) Produces ATP d) Absorbs nutrients Maintains electrochemical gradient vital for cell function. 43 / 45 Category: JAMB Chemistry 2023 43. Most electronegative element? a) Sodium b) Calcium c) Fluorine d) Chlorine Fluorine has the highest electronegativity on periodic table. 44 / 45 Category: JAMB Chemistry 2023 44. Main product of hydrocarbon combustion? a) Carbon monoxide b) $CO_2$ and $H_2O$ c) Carbon soot d) Hydrogen gas $CO_2$ and $H_2O$ are complete combustion products. 45 / 45 Category: JAMB Chemistry 2023 45. Energy-releasing biological process? a) Photosynthesis b) Respiration c) Melting d) Sublimation Respiration releases energy by metabolizing glucose. 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