2018 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 2018 JAMB CHEMISTRY PAST QUESTIONS AND ANSWERS 1 / 40 Category: Jamb Chemistry 2018 1. Periodic classification arranges elements based on what property? a) Atomic weights. b) Isotopic weights. c) Molecular weights. d) Atomic numbers. Elements are arranged by atomic numbers, determining the periodic trends and chemical properties. 2 / 40 Category: Jamb Chemistry 2018 2. What is the new concentration after diluting 1L of 2.2M $H_2SO_4$? a) 2.2 M b) 1.1 M c) 0.22 M d) 0.11 M Use dilution formula $C_1V_1 = C_2V_2$ to calculate resulting concentration after mixing in 10L of water. 3 / 40 Category: Jamb Chemistry 2018 3. In the experiment, what happens to litmus paper initially? a) Bleached b) Green c) Red d) Blue Litmus paper turns red in acidic environments. It indicates the presence of $H^+$ ions. 4 / 40 Category: Jamb Chemistry 2018 4. How to correct the electrochemical series order of given elements? a) Al and Mg b) Zn and Fe c) Zn and Pb d) Pb and H Switch positions of Zn and Fe for accurate arrangement based on standard electrode potentials. 5 / 40 Category: Jamb Chemistry 2018 5. What kinetic theory assumption explains gas molecules’ straight-line motion? a) Elastic collisions b) Repulsion forces c) Attraction-repulsion d) Inelastic collisions Molecules collide elastically, conserving energy during interactions. 6 / 40 Category: Jamb Chemistry 2018 6. Factors affecting solubility of gases in solvents include? a) All factors b) Solvent/solute c) Solute alone d) Solvent/temp/pressure Solubility depends on solvent/solute nature, temperature, and pressure. 7 / 40 Category: Jamb Chemistry 2018 7. Identify correct periodic table trend description. a) Same valence b) Increase valence c) Same shells d) Decreasing nonmetals Valence electrons increase progressively across a period, indicating chemical behavior changes. 8 / 40 Category: Jamb Chemistry 2018 8. Boiling fat with caustic soda is referred to as? a) Hydrolysis b) Esterification c) Acidification d) Saponification Saponification involves hydrolysis of fats into glycerol and soap in alkaline conditions. 9 / 40 Category: Jamb Chemistry 2018 9. Which substances form higher oxides with oxygen? a) $CO_2$, $H_2O$ b) NO, $H_2O$ c) CO, $CO_2$ d) $SO_2$, NO $SO_2$ and NO undergo further oxidation, yielding higher oxidation states. 10 / 40 Category: Jamb Chemistry 2018 10. Why does $MnO_2$ reduce energy need in $KClO_3$ reaction? a) Lower pressure b) Increase area c) Higher reaction rate d) Lower energy barrier Catalyst lowers activation energy, allowing reaction at moderate heat. 11 / 40 Category: Jamb Chemistry 2018 11. How to obtain pure water from a mixture of sand, water, and methanoic acid? a) Fractional distillation b) Filtration + distillation c) Neutralize + distillation d) Neutralize + filtration Filtration removes sand; distillation separates water due to different boiling points. 12 / 40 Category: Jamb Chemistry 2018 12. Mass of aluminum liberated by same electricity as 3.6g of silver. a) 2.7 g b) 1.2 g c) 0.9 g d) 0.3 g Using electrolysis proportionality: $\frac{\text{Mass of Al}}{\text{Mass of Ag}} = \frac{\text{Molar mass Al}}{\text{Molar mass Ag}}$ 13 / 40 Category: Jamb Chemistry 2018 13. What reagents are suitable for nitrogen preparation in a lab? a) Sodium dioxonitrate (III), ammonium chloride b) Sodium trioxonitrate (V), ammonium chloride c) NaCl, ammonium nitrate d) NaCl, ammonium dioxonitrate (III) Sodium dioxonitrate reacts with ammonium chloride to yield nitrogen gas. 14 / 40 Category: Jamb Chemistry 2018 14. How many electrons are in the valence shell of an element with atomic number 14? a) 4 b) 1 c) 2 d) 3 Atomic number 14 corresponds to silicon; configuration $1s^2 2s^2 2p^6 3s^2 3p^2$ gives 4 valence electrons. 15 / 40 Category: Jamb Chemistry 2018 15. Volume of oxygen remaining after reacting $8cm^3$ $H_2$ with $20cm^3$ $O_2$? a) $10cm^3$ b) $12cm^3$ c) $14cm^3$ d) $16cm^3$ Using stoichiometry: $H_2 + \frac{1}{2}O_2 \rightarrow H_2O$; oxygen remaining = $12cm^3$ 16 / 40 Category: Jamb Chemistry 2018 16. Which oxide is not reduced by hydrogen or carbon? a) Lead oxide b) Magnesium oxide c) Copper oxide d) Tin oxide Magnesium oxide is highly stable and resistant to reduction at normal conditions. 17 / 40 Category: Jamb Chemistry 2018 17. What is the correct name for this alkane compound? a) 1-methylpentane b) 3-methylbutane c) 2-methylbutane d) 1-dimethylpropane IUPAC naming rules yield 2-methylbutane as the correct name for this isomer. 18 / 40 Category: Jamb Chemistry 2018 18. Which cation forms a white precipitate soluble in both NaOH and $NH_3$? a) $Zn^{2+}$ b) $Ca^{2+}$ c) $Al^{3+}$ d) $Pb^{2+}$ $Zn^{2+}$ forms amphoteric compounds, dissolving in both bases and ammonia solutions. 19 / 40 Category: Jamb Chemistry 2018 19. Calculate NaOH concentration for 2g dissolved in $100cm^3$ solution. a) 0.40 mol $dm^3$ b) 0.50 mol $dm^3$ c) 0.05 mol $dm^3$ d) 0.30 mol $dm^3$ Concentration $C = \frac{\text{Mass}}{\text{Molar mass} \times \text{Volume (L)}}$ yields 0.50 mol $dm^3$ 20 / 40 Category: Jamb Chemistry 2018 20. How many atoms are in 6.0g of magnesium? a) $1.20 \times 10^{22}$ b) $2.41 \times 10^{22}$ c) $1.51 \times 10^{32}$ d) $3.02 \times 10^{32}$ Using formula Atoms = Moles $\times N_A$; moles = $\frac{\text{Mass}}{\text{Molar mass}}$ 21 / 40 Category: Jamb Chemistry 2018 21. Which radioisotope is used for checking faults in welds and castings? a) Carbon-14 b) Phosphorus-32 c) Cobalt-60 d) Iodine-131 Cobalt-60 emits gamma radiation, suitable for industrial imaging to check welds and castings. 22 / 40 Category: Jamb Chemistry 2018 22. Why do beryllium and aluminum share similar properties? a) Both are metals b) Same group c) Same period d) Diagonal relationship Diagonal relationships in the periodic table lead to similarities in chemical properties. 23 / 40 Category: Jamb Chemistry 2018 23. What is the equilibrium constant for $mE + nF \rightleftharpoons pG + qH$? a) $\frac{[E]^m[F]^n}{[G]^p[H]^q}$ b) $\frac{[E][F]}{[G][H]}$ c) $\frac{[G]^p[H]^q}{[E]^m[F]^n}$ d) $\frac{[G][H]}{[E][F]}$ Equilibrium constant $K = \frac{[G]^p[H]^q}{[E]^m[F]^n}$ 24 / 40 Category: Jamb Chemistry 2018 24. What do reactions of ammonia demonstrate? (e.g. reducing CuO, forming HCl.) a) Basic properties b) Acidic properties c) Reducing properties d) Oxidizing properties Ammonia acts as a reducing agent in these chemical reactions. 25 / 40 Category: Jamb Chemistry 2018 25. What salt reacts with HCl to produce a gas that decolorizes acidified $KMnO_4$? a) $Na_2SO_4$ b) $Na_2SO_3$ c) $Na_2S$ d) $Na_2CO_3$ $Na_2SO_3$ reacts to produce $SO_2$ gas, decolorizing $KMnO_4$ 26 / 40 Category: Jamb Chemistry 2018 26. What gives soda water and soft drinks their characteristic taste? a) $CO_2$ (carbon IV oxide) b) CO (carbon II oxide) c) Soda d) Glucose The taste comes from dissolved $CO_2$ forming carbonic acid. 27 / 40 Category: Jamb Chemistry 2018 27. Which of the following are mixtures? Petroleum, rubber latex, vulcanizer solution, $CS_2$? a) Petroleum, latex, vulcanizer solution b) Petroleum, latex, $CS_2$ c) Petroleum and latex only d) Petroleum and $CS_2$ Petroleum, latex, and vulcanizer’s solution are mixtures. Carbon disulfide is a compound. 28 / 40 Category: Jamb Chemistry 2018 28. A balanced equation obeys which law? Conservation of mass, proportions, or energy? a) Mass conservation b) Definite proportions c) Multiple proportions d) Energy conservation Balanced equations show the law of conservation of mass: matter is neither created nor destroyed. 29 / 40 Category: Jamb Chemistry 2018 29. What are the moles of a gas occupying $10dm^3$ at 4 atm and 273°C? a) 0.89 mol b) 1.90 mol c) 3.80 mol d) 5.70 mol Using $PV = nRT$, solving for $n$ gives $\frac{P \cdot V}{R \cdot T} \approx 0.89$ moles. 30 / 40 Category: Jamb Chemistry 2018 30. At what temperature does gas volume reach zero by Charles’ Law? a) 0°C b) -100°C c) -273°C d) -373°C Absolute zero is -273°C, where gas theoretically has zero volume. 31 / 40 Category: Jamb Chemistry 2018 31. Which substance is used to ripen fruits? a) Ethene b) Propane c) Methane d) Butane Ethene acts as a natural ripening agent for fruits. 32 / 40 Category: Jamb Chemistry 2018 32. Which sulfide is insoluble in dilute HCl? FeS, CuS, ZnS, or $Na_2S$? a) FeS b) CuS c) ZnS d) $Na_2S$ CuS is insoluble in dilute hydrochloric acid due to its low solubility. 33 / 40 Category: Jamb Chemistry 2018 33. What is the pH of a 0.001 $moldm^{-3}$ NaOH solution? a) 14 b) 13 c) 12 d) 11 Using $pH = 14 – pOH$ and $pOH = -\log[OH^-]$, pH = 11. 34 / 40 Category: Jamb Chemistry 2018 34. What type of bonding exists in $[Cu(NH_3]_4^{2+}$? a) Coordinate b) Electrovalent c) Metallic d) Covalent Coordinate bonding exists between $Cu^{2+}$ and $NH_3$ ligands. 35 / 40 Category: Jamb Chemistry 2018 35. Which is an example of chemical change? Dissolution, rusting, melting, or distillation? a) Dissolution b) Rusting c) Melting d) Distillation Rusting is a chemical change involving oxidation. 36 / 40 Category: Jamb Chemistry 2018 36. To double gas volume and pressure, to what temperature must gas at 273K be heated? a) 298K b) 546K c) 819K d) 1092K Applying ideal gas law, doubling both volume and pressure requires T = 1092K. 37 / 40 Category: Jamb Chemistry 2018 37. What happens to particle kinetic energy with temperature rise? a) Decreases b) Increases c) Becomes zero d) Remains constant Kinetic energy increases as particle motion becomes faster. 38 / 40 Category: Jamb Chemistry 2018 38. Which element is used in match production? a) Nitrogen b) Aluminum c) Copper d) Sulfur Sulfur is a key component in match production for ignition. 39 / 40 Category: Jamb Chemistry 2018 39. Which gas cannot be dried using concentrated $H_2SO_4$? HCl, $NH_3$, $Cl_2$, $SO_2$? a) HCl b) $NH_3$ c) $Cl_2$ d) $SO_2$ Ammonia reacts with concentrated sulfuric acid, so it cannot be dried using it. 40 / 40 Category: Jamb Chemistry 2018 40. Consecutive alkanes differ by what unit? CH, $CH_2$, $CH_3$, $C_nH_n$? a) CH b) $CH_2$ c) $CH_3$ d) $C_nH_n$ Consecutive members of an alkane homologous series differ by $CH_2$ group. Your score is The average score is 0% LinkedIn Facebook Twitter VKontakte 0% Restart quiz Anonymous feedback Send feedback
