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Chemistry past questions: WAEC SSCE 2024

50 objective questions, with answers. Free to read and practise.

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50 questions, one at a time, marked as you go or at the end. No account needed.

  1. 1.
    \(_8\) X \(^{2-}\) and \(_{10}\) Y are
    1. A.isomers
    2. B.isotopes
    3. C.allotropes
    4. D.isoelectronic
    Show answer

    Answer: D isoelectronic

  2. 2.
    A saturated solution at 30 \(^0\) C will normally produce crystals at a temperature of
    1. A.50 \(^0\) C
    2. B.40 \(^0\) C
    3. C.35 \(^0\) C
    4. D.20 \(^0\) C
    Show answer

    Answer: D 20 \(^0\) C

  3. 3.
    A weak acid is one which
    1. A.is not corrosive
    2. B.completely ionizes in water
    3. C.does not produce salt with alkali
    4. D.slightly ionizes in water
    Show answer

    Answer: D slightly ionizes in water

  4. 4.
    According to the collision theory of reaction rates, which of the following conditions is not required for two molecules to react? The molecules must
    1. A.come into contact without loss of energy on colliding with each other
    2. B.collide with enough energy to overcome the activation energy barrier
    3. C.collide in an orientation that makes formation of product possible
    4. D.possess enough speed to overcome intermolecular forces of attraction
    Show answer

    Answer: A come into contact without loss of energy on colliding with each other

  5. 5.
    Aluminium is suitable for making alloys for aircraft construction because it
    1. A.is hard and brittle
    2. B.is light and very resistant to corrosion
    3. C.has high density and also a non-conductor of electricity
    4. D.is amphoteric and allotropic
    Show answer

    Answer: B is light and very resistant to corrosion

  6. 6.
    An atom of an element in the ground state contains 8 valence electrons. The element is considered as a
    1. A.metal
    2. B.semi-metal
    3. C.noble gas
    4. D.halogen
    Show answer

    Answer: C noble gas

  7. 7.
    At 25 \(^0\) C, the saturated solution of a salt in water was found to contain 0.24g of the salt in 100cm \(^3\) . What is the solubility of the salt in gdm \(^{-1}\) ?
    1. A.0.024
    2. B.0.240
    3. C.2.40
    4. D.24.0
    Show answer

    Answer: C 2.40

  8. 8.
    Bases normally
    1. A.are corrosive
    2. B.turn litmus paper from blue to red
    3. C.turn litmus paper from red to blue
    4. D.are non-metal oxides
    Show answer

    Answer: C turn litmus paper from red to blue

  9. 9.
    Catalysts alter reaction rates by
    1. A.providing an alternative reaction pathway
    2. B.lowering the energy of reaction
    3. C.increasing the surface area of reactants
    4. D.aligning the reactant molecules properly
    Show answer

    Answer: A providing an alternative reaction pathway

  10. 10.
    Consider the reaction represented by the equation: C \(_3\) H \(_8\) + 5 O \(_2\) → 3CO \(_2\) + 4H \(_2\) O If 0.1 mole of C \(_3\) H \(_8\) was completely burnt, what volume of CO \(_2\) would be produced at stp? [volume of gas at stp = 22.4dm \(^3\) mol \(^{-1}\) ].
    1. A.6.72dm \(^3\)
    2. B.2.24dm \(^3\)
    3. C.0.30 dm \(^3\)
    4. D.0.10dm \(^3\)
    Show answer

    Answer: A 6.72dm \(^3\)

  11. 11.
    Consider the reaction represented by the following equation: x Al + yCl \(_2\) → z AlCl \(_3\)
    1. A.2, 3 and 2
    2. B.2, 2 and 3
    3. C.1, 2 and 1
    4. D.1, 1 and 1
    Show answer

    Answer: A 2, 3 and 2

  12. 12.
    Ethane of volume 400 cm \(^3\) was completely burnt in excess oxygen according to the following equation: 2C \(_2\) H \(_6\) \(_(g)\) + 7O \(_2\) \(_(g)\) → 6H \(_2\) O \(_(g)\) + 4CO \(_2\) \(_(g)\) Calculate the volume of steam that would be produced.
    1. A.200 cm \(^3\)
    2. B.400 cm \(^3\)
    3. C.600 cm \(^3\)
    4. D.1200 cm \(^3\)
    Show answer

    Answer: D 1200 cm \(^3\)

  13. 13.
    Ethanedioic acid is an organic solid that can be purified by
    1. A.decantation
    2. B.distillation
    3. C.crystallization
    4. D.filtration
    Show answer

    Answer: C crystallization

  14. 14.
    How many covalent bonds are formed by Nitrogen?
    1. A.1
    2. B.2
    3. C.3
    4. D.4
    Show answer

    Answer: C 3

  15. 15.
    How many isomers can be formed from a compound with molecular formula C \(_5\) H \(_{12}\) ?
    1. A.One
    2. B.Two
    3. C.Three
    4. D.Four
    Show answer

    Answer: C Three

  16. 16.
    In ethanol, the attractive forces between adjacent molecules are
    1. A.covalent bonds only
    2. B.hydrogen bonds only
    3. C.hydrogen bonding and Van der Waal's forces
    4. D.Van der Waal's forces only
    Show answer

    Answer: C hydrogen bonding and Van der Waal's forces

  17. 17.
    Isotopes of the same element have similar chemical properties because they have the same number of
    1. A.nuclides
    2. B.protons
    3. C.neutrons
    4. D.atoms
    Show answer

    Answer: B protons

  18. 18.
    Naturally occurring Boron is made up of 19.9% \(^{10}\) B and 80.1% \(^{11}\) B. The relative atomic mass of Boron is
    1. A.21.0
    2. B.10.8
    3. C.10.5
    4. D.10.0
    Show answer

    Answer: B 10.8

  19. 19.
    Pairs of outermost shell electrons which are not used in bonding are
    1. A.lone pairs
    2. B.bonding pairs
    3. C.valence electrons
    4. D.electrovalent electrons
    Show answer

    Answer: A lone pairs

  20. 20.
    Pure water contaminated with quicklime will have a pH of
    1. A.1
    2. B.6
    3. C.7
    4. D.8
    Show answer

    Answer: D 8

  21. 21.
    Tetraoxosulphate (VI) acid is considered as a heavy chemical because
    1. A.its relative molecular mass is high
    2. B.a high tonnage is produced every year
    3. C.it is an inorganic chemical
    4. D.it is used to manufacture heavy chemicals
    Show answer

    Answer: B a high tonnage is produced every year

  22. 22.
    The branch of science that deals with the nature and properties of substances and how one substance can be converted to another is known as
    1. A.biology
    2. B.chemistry
    3. C.geography
    4. D.physics
    Show answer

    Answer: B chemistry

  23. 23.
    The electron configuration 1S \(^2\) 2S \(^2\) 2P \(_x\) \(^2\) contravenes the
    1. A.Pauli's exclusion principle
    2. B.Aufbau's principle
    3. C.octet rule
    4. D.Hund's rule
    Show answer

    Answer: D Hund's rule

  24. 24.
    The electron configuration of \(_{29}\) Cu is
    1. A.1S \(^2\) 2S \(^2\) 2P \(^6\) 3S \(^2\) 3P \(^6\) 4S \(^1\) 3d \(^{10}\)
    2. B.1S \(^2\) 2S \(^2\) 2P \(^6\) 3S \(^2\) 3P \(^6\) 4S \(^3\) 3d \(^9\)
    3. C.1S \(^2\) 2S \(^2\) 2P \(^5\) 3S \(^2\) 3P \(^6\) 4S \(^2\) 3d \(^{10}\)
    4. D.1S \(^2\) 2S \(^2\) 2P \(^6\) 3S \(^2\) 3P \(^2\) 4S \(^1\) 3d \(^{10}\)
    Show answer

    Answer: A 1S \(^2\) 2S \(^2\) 2P \(^6\) 3S \(^2\) 3P \(^6\) 4S \(^1\) 3d \(^{10}\)

  25. 25.
    The following organic compounds are polymers except
    1. A.rubber
    2. B.starch
    3. C.proteins
    4. D.fats
    Show answer

    Answer: D fats

  26. 26.
    The hardest form of carbon is
    1. A.charcoal
    2. B.coke
    3. C.diamond
    4. D.graphite
    Show answer

    Answer: C diamond

  27. 27.
    The main function of limestone in the blast furnace during the extraction of iron is to
    1. A.act as catalyst
    2. B.remove impurities
    3. C.act as a reducing agent
    4. D.supply Carbon(IV) oxide
    Show answer

    Answer: B remove impurities

  28. 28.
    The metallic bonding in aluminium is strong because of large number of
    1. A.delocalized electrons
    2. B.immobile electrons
    3. C.lone pair electrons
    4. D.valence electrons
    Show answer

    Answer: A delocalized electrons

  29. 29.
    The most important ore of aluminium is
    1. A.bauxite
    2. B.haematite
    3. C.magnetite
    4. D.monazite
    Show answer

    Answer: A bauxite

  30. 30.
    The number of shared pair of electrons in a molecule of methane is
    1. A.2
    2. B.4
    3. C.6
    4. D.8
    Show answer

    Answer: B 4

  31. 31.
    The oxidation number of Chromium in Na \(_2\) Cr \(_2\) O \(_7\) is
    1. A.+2
    2. B.+6
    3. C.+7
    4. D.+12
    Show answer

    Answer: B +6

  32. 32.
    The oxidation number of iron, in its free state is
    1. A.0
    2. B.+1
    3. C.+2
    4. D.+3
    Show answer

    Answer: A 0

  33. 33.
    The percentage by mass of Oxygen in MgSO \(_4\) .7H \(_2\) O is [ M \(_r\) of MgSO \(_4\) .7H \(_2\) O = 246 ]
    1. A.26.0%
    2. B.45.5%
    3. C.71.5%
    4. D.84.0%
    Show answer

    Answer: C 71.5%

  34. 34.
    The product formed when concentrated sodium chloride solution is electrolysed using carbon electrodes is
    1. A.chloride water
    2. B.hydrochloric acid
    3. C.sodium hydroxide
    4. D.sodium oxochlorate (I)
    Show answer

    Answer: C sodium hydroxide

  35. 35.
    The product of the reaction between ethanol and excess acidified K \(_2\) Cr \(_2\) O \(_7\) is
    1. A.CH \(_2\) =CH \(_2\)
    2. B.CH \(_3\) OCH \(_3\)
    3. C.CH \(_3\) COOH
    4. D.CH \(_3\) CH \(_3\)
    Show answer

    Answer: C CH \(_3\) COOH

  36. 36.
    The reaction represented by the equation: Ni \(^{2+}\) \((_{aq}\) ) + Fe \((_s\) ) → Ni \((_s\) ) + Fe \(^{2+}\) \((_{aq}\) ) is a redox reaction because
    1. A.Ni \(^{2+}\) ions are oxidized and Fe acts as a oxidizing agent
    2. B.Ni \(^{2+}\) ions are oxidized and Fe acts as a reducing agent
    3. C.Ni \(^{2+}\) ions are reduced and Fe acts as an oxidizing agent
    4. D.Ni \(^{2+}\) ions are reduced and Fe acts as a reducing agent
    Show answer

    Answer: D Ni \(^{2+}\) ions are reduced and Fe acts as a reducing agent

  37. 37.
    The volume of 22g of CO \(_2\) at stp is equivalent to [C =12, O =16, molar volume at stp = 22.4 dm \(^3\) ]
    1. A.22.0 dm \(^3\)
    2. B.22.4 dm \(^3\)
    3. C.11.2 dm \(^3\)
    4. D.5.6 dm \(^3\)
    Show answer

    Answer: C 11.2 dm \(^3\)

  38. 38.
    Water pipes are produced from
    1. A.polyethene
    2. B.Perspex
    3. C.polystyrene
    4. D.poly vinyl chloride
    Show answer

    Answer: D poly vinyl chloride

  39. 39.
    When an element exists in two or more forms in the same physical state, it exhibits
    1. A.isotopy
    2. B.allotropy
    3. C.isobars
    4. D.isomerism
    Show answer

    Answer: B allotropy

  40. 40.
    When s and p block elements react, the bond formed is
    1. A.electrovalent
    2. B.covalent
    3. C.metallic
    4. D.dative-covalent
    Show answer

    Answer: A electrovalent

  41. 41.
    Which of the following arrangements of elements is in order of increasing ionization energy?
    1. A.Si, Al, S, P
    2. B.S, P, Si, Al
    3. C.Al, Si, P, S
    4. D.P, Si, S, Al
    Show answer

    Answer: C Al, Si, P, S

  42. 42.
    Which of the following compounds is formed by the oxidation of ethanol?
    1. A.C \(_2\) H \(_4\) CO \(_2\) H
    2. B.C \(_2\) H \(_5\) OH
    3. C.CH \(_3\) OH
    4. D.CH \(_3\) CO \(_2\) H
    Show answer

    Answer: D CH \(_3\) CO \(_2\) H

  43. 43.
    Which of the following conditions are necessary for the preparation of alkanoates from alkanols and alkanoic acid?
    1. A.Water and NaOH
    2. B.Conc. H \(_2\) SO \(_4\) and heat
    3. C.NaOH and heat
    4. D.water and aqueous HCl
    Show answer

    Answer: B Conc. H \(_2\) SO \(_4\) and heat

  44. 44.
    Which of the following functional groups is present in alkanoic acid?
    1. A.-COOH
    2. B.-OH
    3. C.-COOR
    4. D.-CHO
    Show answer

    Answer: A -COOH

  45. 45.
    Which of the following gases could be collected by downward displacement of air?
    1. A.Chlorine
    2. B.Hydrogen
    3. C.hydrogen chloride
    4. D.Sulphur(IV) oxide
    Show answer

    Answer: B Hydrogen

  46. 46.
    Which of the following household liquids would be effective in treating someone with too much acid in the stomach?
    1. A.Strong salt solution with pH 7.0
    2. B.Tomato juice with pH 4.1
    3. C.Milk of Magnesia with pH 10.5
    4. D.Black coffee with pH 5.0
    Show answer

    Answer: C Milk of Magnesia with pH 10.5

  47. 47.
    Which of the following is a monomer of polythene?
    1. A.Ethanol
    2. B.Vinyl chloride
    3. C.Ethene
    4. D.Ethane
    Show answer

    Answer: C Ethene

  48. 48.
    Which of the following statements about ammonium salt is correct? It
    1. A.dissolves in water to form solution of pH > 1
    2. B.dissolves in water to form solution of pH < 7
    3. C.does not decompose on heating
    4. D.is insoluble in water
    Show answer

    Answer: B dissolves in water to form solution of pH < 7

  49. 49.
    Which of the following statements describes transition elements? They
    1. A.are very reactive
    2. B.have low melting points
    3. C.possess variable oxidation state
    4. D.form colourless salts
    Show answer

    Answer: C possess variable oxidation state

  50. 50.
    Which of the following substances has the lowest boiling point?
    1. A.Aqueous sodium chloride
    2. B.Ethanol
    3. C.Tetrachloromethane
    4. D.Water
    Show answer

    Answer: C Tetrachloromethane

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