2020 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% 0 votes, 0 avg Created by Jamb TutorJamb Chemistry 2020 JAMB CHEMISTRY PAST QUESTIONS AND ANSWERS 1 / 40 Category: JAMB Chemistry 2020 1. $$\text{The electronic configuration is } 1s^2 2s^2 2p^6 3s^2 3p^3.\text{ How many unpaired electrons?}$$ a) $$\text{5.}$$ b) $$\text{4.}$$ c) $$\text{3.}$$ d) $$\text{2.}$$ $$\text{Three unpaired electrons are found in 3p orbitals.}$$ 2 / 40 Category: JAMB Chemistry 2020 2. $$\text{Which can be obtained by fractional distillation?}$$ a) $$\text{Nitrogen from liquid air.}$$ b) $$\text{NaCl from seawater.}$$ c) $$\text{Iodine in CCl}_4.}$$ d) $$\text{Sulphur in CS}_2.}$$ $$\text{Nitrogen can be separated from liquid air via fractional distillation.}$$ 3 / 40 Category: JAMB Chemistry 2020 3. $$\text{Duralumin consists of aluminum, copper, and?}$$ a) $$\text{Zinc, gold.}$$ b) $$\text{Lead, manganese.}$$ c) $$\text{Nickel, silver.}$$ d) $$\text{Manganese, magnesium.}$$ $$\text{Duralumin includes manganese and magnesium.}$$ 4 / 40 Category: JAMB Chemistry 2020 4. $$\text{An example of a polysaccharide is?}$$ a) $$\text{Dextrose.}$$ b) $$\text{Mannose.}$$ c) $$\text{Glucose.}$$ d) $$\text{Starch.}$$ $$\text{Starch is a polysaccharide; others are monosaccharides.}$$ 5 / 40 Category: JAMB Chemistry 2020 5. $$\text{8 g CH}_4\text{ occupies 11.2 L at S.T.P. Volume for 22 g C}_3H}_8?$$ a) $$\text{3.7 dm}^3.}$$ b) $$\text{11.2 dm}^3.}$$ c) $$\text{22.4 dm}^3.}$$ d) $$\text{33 dm}^3.}$$ $$\text{C}_3H}_8\text{ has molar mass of 44 g/mol; it occupies 22.4 dm}^3.}$$ 6 / 40 Category: JAMB Chemistry 2020 6. $$\text{Best treatment after spilling conc. } H}_2SO}_4\text{ on skin?}$$ a) $$\text{Cool water.}$$ b) $$\text{NaOH solution.}$$ c) $$\text{Iodine solution.}$$ d) $$\text{HNO}_3 solution.}$$ $$\text{Wash affected skin with cool running water immediately.}$$ 7 / 40 Category: JAMB Chemistry 2020 7. $$\text{Which gas law is illustrated in this graph?}$$ a) $$\text{Boyle's law.}$$ b) $$\text{Charles' law.}$$ c) $$\text{Gay-Lussac.}$$ d) $$\text{Graham's law.}$$ $$\text{This graph represents Boyle’s law, showing } P\propto \frac{1}{V}.}$$ 8 / 40 Category: JAMB Chemistry 2020 8. $$\text{What are possible oxidation numbers for } Z=17?$$ a) $$\text{-1, +7.}$$ b) $$\text{-1, +6.}$$ c) $$\text{-3, +5.}$$ d) $$\text{-2, +6.}$$ $$\text{Z = 17 (chlorine) has } -1 \text{ and } +7.}$$ 9 / 40 Category: JAMB Chemistry 2020 9. $$\text{Which process converts coal to coal tar, coke, etc.?}$$ a) $$\text{Steam distillation.}$$ b) $$\text{Destructive distillation.}$$ c) $$\text{Liquefaction.}$$ d) $$\text{Hydrolysis.}$$ $$\text{Destructive distillation of coal produces tar, coke, gas.}$$ 10 / 40 Category: JAMB Chemistry 2020 10. $$\text{Ash in black soap provides?}$$ a) $$\text{Acid.}$$ b) $$\text{Ester of acid.}$$ c) $$\text{Alkali.}$$ d) $$\text{Alkanol.}$$ $$\text{Ash provides alkali needed for saponification.}$$ 11 / 40 Category: JAMB Chemistry 2020 11. $$\text{Gas flame produced when } CaC}_2\text{ is wetted and ignited?}$$ a) $$\text{Oxyethene.}$$ b) $$\text{Oxyhydrocarbon.}$$ c) $$\text{Oxyacetylene.}$$ d) $$\text{Oxymethane.}$$ $$\text{Reaction produces acetylene gas igniting an oxyacetylene flame.}$$ 12 / 40 Category: JAMB Chemistry 2020 12. $$\text{Which is a mixture?}$$ a) $$\text{Sugar.}$$ b) $$\text{Seawater.}$$ c) $$\text{NaCl.}$$ d) $$\text{Iron filings.}$$ $$\text{Seawater contains dissolved salts and impurities, making it a mixture.}$$ 13 / 40 Category: JAMB Chemistry 2020 13. $$\text{If half oxygen is removed from a 2.76 L container, pressure becomes?}$$ a) $$\text{1.650 atm.}$$ b) $$\text{0.825 atm.}$$ c) $$\text{0.413 atm.}$$ d) $$\text{0.275 atm.}$$ $$\text{Pressure halves; final pressure is } 0.413 \text{ atm.}$$ 14 / 40 Category: JAMB Chemistry 2020 14. $$\text{Four elements: 4, 10, 12, 14; which is noble gas?}$$ a) $$\text{P.}$$ b) $$\text{Q.}$$ c) $$\text{R.}$$ d) $$\text{S.}$$ $$\text{Atomic number 10 is neon, a noble gas.}$$ 15 / 40 Category: JAMB Chemistry 2020 15. $$\text{Decomposition products of NH}_4NO}_3$$ a) $$\text{N}_2\text{O, H}_2\text{O.}$$ b) $$\text{NH}_3\text{ and oxide.}$$ c) $$\text{N}_2\text{ and H}_2\text{O.}$$ d) $$\text{N}_2\text{O}_4\text{ and H}_2\text{O.}$$ $$\text{Thermal decomposition produces N}_2\text{O and H}_2\text{O.}$$ 16 / 40 Category: JAMB Chemistry 2020 16. $$\text{Valence electrons for 31}_15\text{P}?$$ a) $$\text{3.}$$ b) $$\text{4.}$$ c) $$\text{15.}$$ d) $$\text{31.}$$ $$\text{Group 15 elements have 5 valence electrons.}$$ 17 / 40 Category: JAMB Chemistry 2020 17. $$\text{Molecules of CO}_2\text{ from 10g CaCO}_3\text{ with 0.2 dm}^3\text{ 1M HCl?}$$ a) $$\text{1.00}\times 10^{23}.}$$ b) $$\text{6.02}\times 10^{23}.}$$ c) $$\text{6.02}\times 10^{22}.}$$ d) $$\text{6.02}\times 10^{24}.}$$ $$\text{One mole CaCO}_3\text{ reacts fully; } 6.02\times 10^{22}\text{ CO}_2\text{ molecules formed.}$$ 18 / 40 Category: JAMB Chemistry 2020 18. $$\text{Relative molecular mass for gas at S.T.P; 1.58 g occupies 500 cm}^3?$$ a) $$\text{28.}$$ b) $$\text{32.}$$ c) $$\text{44.}$$ d) $$\text{71.}$$ $$\text{Relative molar mass } \frac{1.58}{(\frac{500}{22400})} = 71.}$$ 19 / 40 Category: JAMB Chemistry 2020 19. $$\text{Gas rekindling glowing splint?}$$ a) $$\text{NO}_2.}$$ b) $$\text{NO.}$$ c) $$\text{N}_2.}$$ d) $$\text{Cl}_2.}$$ $$\text{Oxygen rekindles glowing splints; others do not.}$$ 20 / 40 Category: JAMB Chemistry 2020 20. $$\text{Molecular geometry for NH}_3$$ a) $$\text{Trigonal planar.}$$ b) $$\text{Octahedral.}$$ c) $$\text{Square planar.}$$ d) $$\text{Tetrahedral.}$$ $$\text{Ammonia forms tetrahedral geometry due to lone pairs.}$$ 21 / 40 Category: JAMB Chemistry 2020 21. $$\text{Effect on pH if conc. HCl is added to a solution of pH 3.4?}$$ a) $$\text{Less than 3.4.}$$ b) $$\text{Greater than 3.4.}$$ c) $$\text{Unaltered.}$$ d) $$\text{Pure water.}$$ $$\text{Adding HCl increases acidity, reducing pH below 3.4.}$$ 22 / 40 Category: JAMB Chemistry 2020 22. $$\text{Chromatography separates components by rates of?}$$ a) $$\text{Diffusion.}$$ b) $$\text{Migration.}$$ c) $$\text{Reaction.}$$ d) $$\text{Sedimentation.}$$ $$\text{Chromatography depends on migration differences in solvent.}$$ 23 / 40 Category: JAMB Chemistry 2020 23. $$\text{Deliquescent substances are also?}$$ a) $$\text{Efflorescent.}$$ b) $$\text{Anhydrous.}$$ c) $$\text{Hygroscopic.}$$ d) $$\text{Insoluble.}$$ $$\text{Deliquescent substances absorb moisture, hence hygroscopic.}$$ 24 / 40 Category: JAMB Chemistry 2020 24. $$\text{Why use helium in balloons?}$$ a) $$\text{Light, combustible.}$$ b) $$\text{Light, non-combustible.}$$ c) $$\text{Heavy, combustible.}$$ d) $$\text{Heavy, non-combustible.}$$ $$\text{Helium is light and non-combustible, ideal for balloons.}$$ 25 / 40 Category: JAMB Chemistry 2020 25. $$\text{Heat from dissolving 32 g CuSO}_4\text{ in 1 dm}^3\text{ generates 13.0 kJ. Solution heat?}$$ a) $$\text{26 kJ/mol.}$$ b) $$\text{65 kJ/mol.}$$ c) $$\text{130 kJ/mol.}$$ d) $$\text{260 kJ/mol.}$$ $$\text{Solution heat per mole is } \frac{13.0}{\frac{32}{160}} = 65 \text{ kJ/mol.}$$ 26 / 40 Category: JAMB Chemistry 2020 26. $$\text{Formula of MCl where M = 27, Cl = 35.5; MCl = 20.22%?}$$ a) $$\text{MCl.}$$ b) $$\text{MCl}_2.}$$ c) $$\text{MCl}_3.}$$ d) $$\text{M}_2Cl}_6.}$$ $$\text{Mass ratio confirms formula as MCl.}$$ 27 / 40 Category: JAMB Chemistry 2020 27. $$\text{Electricity for 0.125 mol oxygen molecules during electrolysis?}$$ a) $$\text{24,125 C.}$$ b) $$\text{48,250 C.}$$ c) $$\text{72,375 C.}$$ d) $$\text{96,500 C.}$$ $$\text{Faraday’s law: } Q = nF \Rightarrow Q = 0.125 \times 96500 = 12062.5 \text{ C.}$$ 28 / 40 Category: JAMB Chemistry 2020 28. $$\text{Which type of bonding forms no new substances?}$$ a) $$\text{Metallic.}$$ b) $$\text{Covalent.}$$ c) $$\text{Coordinate.}$$ d) $$\text{Electrovalent.}$$ $$\text{Metallic bonds don’t form compounds but hold metals together.}$$ 29 / 40 Category: JAMB Chemistry 2020 29. $$\text{Which compound avoids HCN and hydroxylamine reactions?}$$ a) $$\text{Alkene.}$$ b) $$\text{Alkanal.}$$ c) $$\text{Alkanone.}$$ d) $$\text{Alkanoic acid.}$$ $$\text{Alkanes lack reactive functional groups for these reactions.}$$ 30 / 40 Category: JAMB Chemistry 2020 30. $$\text{Substance for vulcanizing rubber?}$$ a) $$\text{Chlorine.}$$ b) $$\text{H}_2O_2.}$$ c) $$\text{Sulphur.}$$ d) $$\text{H}_2SO}_4.}$$ $$\text{Sulphur cross-links rubber molecules during vulcanization.}$$ 31 / 40 Category: JAMB Chemistry 2020 31. $$\text{Industrial solvent for grease removal?}$$ a) $$\text{Tetrachloromethane.}$$ b) $$\text{Chloromethane.}$$ c) $$\text{Trichloromethane.}$$ d) $$\text{Dichloromethane.}$$ $$\text{Tetrachloromethane removes grease due to its nonpolar solvent properties.}$$ 32 / 40 Category: JAMB Chemistry 2020 32. $$\text{Water mass from 8.0g H reacting with excess O}_2?$$ a) $$\text{8.0 g.}$$ b) $$\text{16.0 g.}$$ c) $$\text{36.0 g.}$$ d) $$\text{72.0 g.}$$ $$\text{H}_2 + \frac{1}{2} O_2 \rightarrow H_2O; \text{Water formed = 36.0 g.}$$ 33 / 40 Category: JAMB Chemistry 2020 33. $$\text{Proteins in acidic solutions undergo?}$$ a) $$\text{Substitution.}$$ b) $$\text{Fermentation.}$$ c) $$\text{Hydrolysis.}$$ d) $$\text{Polymerization.}$$ $$\text{Proteins hydrolyze into amino acids in acidic solutions.}$$ 34 / 40 Category: JAMB Chemistry 2020 34. $$\text{General formula of alkanals?}$$ a) $$\text{R}_2CO.}$$ b) $$\text{RCHO.}$$ c) $$\text{ROH.}$$ d) $$\text{RCOOR.}$$ $$\text{Alkanals are aldehydes with formula RCHO.}$$ 35 / 40 Category: JAMB Chemistry 2020 35. $$\text{Cathode rays deflected onto electrometer electrode cause?}$$ a) $$\text{Bipolar.}$$ b) $$\text{Negatively charged.}$$ c) $$\text{Positively charged.}$$ d) $$\text{Neutral.}$$ $$\text{Electrons in cathode rays charge electrode negatively.}$$ 36 / 40 Category: JAMB Chemistry 2020 36. $$\text{Creating multiple organic compounds from a single precursor is?}$$ a) $$\text{Polymerization.}$$ b) $$\text{Saponification.}$$ c) $$\text{Hydration.}$$ d) $$\text{Condensation.}$$ $$\text{Condensation forms multiple organic compounds.}$$ 37 / 40 Category: JAMB Chemistry 2020 37. $$\text{Highest melting point among ice, water, ammonium nitrate, lead?}$$ a) $$\text{Ice.}$$ b) $$\text{Water.}$$ c) $$\text{Ammonium nitrate.}$$ d) $$\text{Lead.}$$ $$\text{Lead’s metallic structure gives highest melting point.}$$ 38 / 40 Category: JAMB Chemistry 2020 38. $$\text{pH of a solution at 8.4 is?}$$ a) $$\text{Acidic.}$$ b) $$\text{Alkaline.}$$ c) $$\text{Neutral.}$$ d) $$\text{Basic.}$$ $$\text{pH above 7 indicates basic or alkaline solution.}$$ 39 / 40 Category: JAMB Chemistry 2020 39. $$\text{Why metallic bonds exhibit sea of electrons?}$$ a) $$\text{Delocalized electrons.}$$ b) $$\text{Valence electrons.}$$ c) $$\text{Covalent bonds.}$$ d) $$\text{Ionic bonds.}$$ $$\text{Delocalized electrons allow metallic conductivity and bonding.}$$ 40 / 40 Category: JAMB Chemistry 2020 40. $$\text{Solution of NaOH has pH?}$$ a) $$\text{5.}$$ b) $$\text{7.}$$ c) $$\text{13.}$$ d) $$\text{14.}$$ $$\text{NaOH’s strong alkalinity gives pH 14.}$$ Your score is The average score is 0% LinkedIn Facebook Twitter VKontakte 0% Restart quiz Anonymous feedback Send feedback
