(Chemistry 2023) Model past questions and answers

I sincerely welcome you to an online platform like this. This is poscholar, and we are committed to giving students, Jambites, undergraduate, and the likes information that will be of immense benefit to them as there journey in thier academics. Did you choose chemistry among your subject combination for your UTME exams? if yes, then you are in the right place because we have happily compiled UTME past question and answers for Chemistry Jamb. We believe this will aid your learning as you get to familiarise yourself with the patterns. You can study the 40 (forty) Jamb Chemistry past questions and answers for 2023 by checking the content below or using the table of content below to navigate to the number of your choice

1. Which of the following elements will exhibit the most electronegative character? (a) Al (b) Si (c) P (d) S The correct answer is: (d) S 2. Acid hydrolysis of nitriles will yield? (a) Alkanes (b) Aldehydes (c) Carboxylic acids (d) Alcohols The correct answer is: (c) Carboxylic acids 3. How many isomers of C4H9OH will be tertiary alkanol? (a) 1 (b) 2 (c) 3 (d) 4 The correct answer is: (b) Resonance frequency 4. Which of the following makes oils distinguished from fats? (a) Oil contains a higher proportion of unsaturation (b) Fats contain a higher proportion of unsaturation (c) Oil and fats have the same proportion of unsaturation (d) Neither oil nor fats have unsaturation The correct answer is: (a) Oil contains a higher proportion of unsaturation 5. The characteristic crystalline shape of solid water is due to _____ (a) Covalent bonds (b) Hydrogen bonds (c) Ionic bonds (d) Metallic bonds The correct answer is: (b) Hydrogen bonds 6. The chemical formula for laughing gas is _____ (a) NO (b) ${NO}_2$ (c) ${N}_2{O}$ (d) ${N}_2{O}_5$ The correct answer is: (c) ${N}_2{O}$ 7. The sulphide used in coating electric fluorescent tubes is _____ (a) Iron (II) sulphide (b) Sphalerite (c) Zinc sulphide (d) Sulphide mineral The correct answer is: (c) Zinc sulphide 8. Calculate the volume in ${dm}^3$ of oxygen evolved at s.t.package. When a curent of 5A is passed throught acidified water for 772s (molar volume of gas at stp. = 22.4 ${dm}^3$) (a) 0.056 (b) 0.224 (c) 224000 (d) 56000 The correct answer is: (b) 0.224 9. Hydrogenation of Benzene to cyclohexane is called (a) Cracking (b) Polymerisation (c) Reforming (d) Aromatization The correct answer is: The examiner had aromatization in mind but it does not apply 10. The pollutant that contributes to the depletion of the ozone layer is _____ (a) CF (b) CS (c) CCl (d) CFC The correct answer is: (d) CFC

11. What changes sodium hydroxide pellets to liquid? (a) Oxygen (b) Water vapour (c) Carbon (IV) oxide (d) Nitrogen The correct answer is: (b) Water vapour 12. The compound used as 'antifreeze' in car radiators in cold regions of the world is _____ (a) Ethanol (b) Ethylene glycol (c) Ethanal (d) Propan-1,2-diol The correct answer is: (b) Ethylene glycol 13. What are the laws that form the general gas equation? (a) Boyle's and Charles' laws (b) Boyle's Charles' and Graham's laws (c) Gaps between the coils (d) The area of the coil The correct answer is: (c) Gaps between the coils 14. Chlorine, bromine, and iodine resemble each other in that all (a) Dissolve in alkalis (b) Displace each other from solutions of their salts (c) React violently with hydrogen on heating (d) Are electron donors The correct answer is: (a) Dissolve in alkalis 15. The method suitable for separating suspended particles in liquid is _____ (a) Decantation (b) Distillation (c) Centrifugation (d) Chromatography The correct answer is: (c) Centrifugation 16. A hydrocarbon X has a molar mass of 26 and a carbon atom percentage of 92.3%. What is its molecular formula? (a) ${C}_2{H}_2$ (b) ${C}_2{H}_6$ (c) ${CH}_4$ (d) ${C}_3{H}_8$ The correct answer is: (a) ${C}_2{H}_2$ 17. Silica gel, when exposed to air, turns liquid. What kind of substance is it? (a) Deliquescent (b) Hygroscopic (c) Efflorescent (d) Entropy The correct answer is: (a) Deliquescent 18. In an equilibrium reaction, which of the following conditions indicate that the maximum yield of the product will be obtained? (a) Equilibrium constant is very large (b) $\bigtriangleup{H} = {T}\bigtriangleup{S}$ (c) $\Delta{H} \geq {T}\Delta{S}$ (d) Equilibrium constant is less than zero The correct answer is: (a) Equilibrium constant is very large 19. Under high pressure, real gases do not obey laws because their molecules (a) Have become more energetic (b) Have become less energetic (c) Have become smaller in size (d) Have become larger in size The correct answer is: (b) Have become less energetic 20. The salt responsible for temporary hardness is _____ (a) Calcium sulphate (b) Magnesium chloride (c) Calcium bicarbonate (d) Magnesium sulphate The correct answer is: (c) Calcium bicarbonate

21. Common salt (Nacl) is used to preserve foods. Which of the following properties can be used to determine its purity before use? (a) Solubility in water (b) Melting point (c) Relative density (d) Crystalline nature The correct answer is: (b) Melting point 22. The rate of a chemical reaction is NOT affected by one of these factors (a) Color (b) Concentration (c) Presence of light (d) Surface area The correct answer is: (a) Color 23. The functional group represented in the compound below is _____ (a) Alkanol (b) Alkanal (c) Alkanone (d) Alkanoate The correct answer is: (b) Alkanal 24. On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as _____ (a) Efflorescence (b) Deliquescence (c) Hydroscopy (d) Hydrolysis The correct answer is: (a) Efflorescence 25. Which of the following statements is true of the electrochemical series? (a) Electropositivity of metals increases down the series (b) Electropositivity of non-metals decreases down the series (c) Electronegativity of non-metals decreases (d) Electropositivity of metals decreases down the series The correct answer is: (d) Electropositivity of metals decreases down the series 26. Which of the following pairs are both substances deliquescent? (a) ${CaCl}_2$ and ${H}_2{SO}_4$ (b) NaOH and ${MgSO}_{4}$.${7H}_2{O}$ (c) ${CaCl}_2$ and NaOH (d) CuO and NaCl The correct answer is: (c) ${CaCl}_2$ and NaOH 27. The bond formed between ${H}_2{O}$ and ${H}^{+}$ to form the hydroxonium ${H}_3{O}^{+}$ is (a) Dative (b) Covalent (c) Electrovalent (d) Ionic The correct answer is: (a) Dative 28. Gas molecules are said to be perfectly elastic because (a) They collide without loss of energy (b) They move about in straight lines (c) The distances between them are neglible (d) The volume occupied by them is negligible The correct answer is: (a) They collide without loss of energy 29. A solid that absorbs water from the atmosphere and forms an aqueous solution is _____ (a) Hydrophilic (b) Efflorescent (c) Deliquescent (d) Hygroscopic The correct answer is: (c) Deliquescent 30. Which of the following can undergo both addition reaction and substitution reaction? (a) Benzene (b) Pentane (c) Propane (d) Hexane The correct answer is: (a) Benzene

31. Naming of the organic compound ${CH}_3{(C{H}_2)}_4{CH}_{2}{CH}_{2}{NH}_{2}$ (a) Pentaneamine (b) Heptanamine (c) Hexanamine (d) Octanamine The correct answer is: (b) Heptanamine 32. ${2Cl}_{(aq)}^{-}$ = ${Cl}_{2(g)}$ + ${2e}_{(eq)}^{-}$ The above half-cell reaction occurring at the anode during the electrolysis of dilute ZnCl2 solution is? (a) Ionization (b) Oxidation (c) Reduction (d) Recombination The correct answer is: (b) Oxidation 33. ${CHCl}_{3} + {Cl}_2 \rightarrow {HCL} + {CCl}_4$ The reaction above is an example of? (a) An addition reaction (b) A decomposition reaction (c) A substitution reaction (d) A condensation reaction The correct answer is: (c) A substitution reaction 34. ${c}_x{H}_{y} +{4O}_{2} = {3Co}_2 + {2H}_2{O}$. The hydrocarbon, ${C}_x{H}_{y}$, in the reaction above is? (a) Butene (b) Butane (c) Butyne (d) Butanone The correct answer is: (b) Butane 35. One method of driving the position of equilibrium of an endohermic reaction forward is to? (a) Increase temperature at constant pressure (b) Decrease pressure at constant temperature (c) Cool down the apparatus with water (d) Decreases temperature at constant pressure The correct answer is: (a) Increase temperature at constant pressure 36. 0.92 of ethanol when burned raised the temperature of 50g of water by 28.6K. Calculate the heat of combustion of ethanol. [C = 12, O = 16, H = 1, specific heat capacity of water = $4.2 {Jg}^{-1}{K}^{-1}$] (a) $+3000{KJmol}^{-1}$ (b) $+300{KJmol}^{-1}$ (c) $-300{KJmol}^{-1}$ (d) $-3000{KJmol}^{-1}$ The correct answer is: (c) $-300{KJmol}^{-1}$ 37. The repeating unit in natural rubber is _____ (a) Alkyne (b) Isoprene (c) n-propene (d) neoprene The correct answer is: (b) Isoprene 38. What current in amperes will deposit 2.7g of aluminium in 2 hours? [Al = 27, F = ${96500Cmol}^{-1}$] (a) 32 (b) 8 (c) 4 (d) 16 The correct answer is: (c) 4 39. Steam changes the colour of anhydrous cobalt (II) choride from (a) Blue to pink (b) Red to white (c) White to green (d) White to blue The correct answer is: (a) Blue to pink 40. Which of the following will change when a catalyst is added to a chemical reaction? (a) The activation energy (b) The potential energy of the reactants (c) The heat of the reaction (d) The potential energy of the product The correct answer is: (a) The activation energy Without doubt I believe you are happy with the questions and answers on Jamb Chemistry 2023 you saw above. We have compiled this to ensure students have access to resources that can help them blast their UTME exams. If you have any comment or you observe any flaw do well to leave a comment in the comment-box below and we will get back to you

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