2012 WAEC (WASSCE) Chemistry Past Questions

Questions

1. 1.

   Which of the following halogens is liquid at room temperature?

   1. A.Chlorine
   2. B.Fluorine
   3. C.lodine
   4. D.Bromine

   Show answer

   Answer: D. Bromine

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

2. 2.

   Which of the following devices function on redox reaction? l. Dry cell ll. Car battery III. Electric generator

   1. A.l and lll only
   2. B.ll and lll only
   3. C.l and ll only
   4. D.l, ll and lll

   Show answer

   Answer: C. l and ll only

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

3. 3.

   At ordinary temperature H$_2$O is a liquid while H$_2$S is a gas. This is because H$_2$O has

   1. A.weak intermolecular forces holding its molecules together
   2. B.strong hydrogen bonds holding its molecules together
   3. C.induced dipole-induced dipole forces between its molecules
   4. D.ionic force between its molecules

   Show answer

   Answer: B. strong hydrogen bonds holding its molecules together

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

4. 4.

   The d-block elements are paramagnetic because they

   1. A.contain paired electrons which are repelled by magnetic field
   2. B.contain unpaired electrons in the partially filled 3d-orbital
   3. C.contain paired electrons which are repelled by magnetic field force
   4. D.have delocalized valence electrons

   Show answer

   Answer: B. contain unpaired electrons in the partially filled 3d-orbital

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

5. 5.

   A metal M forms two types of chlorine, MCl$_2$ and MCl$_3$ which of the following laws best explains the relationship between the chlorides? Law of

   1. A.conservation of mass
   2. B.definite proportion
   3. C.multiple proportion
   4. D.reciprocal proportion

   Show answer

   Answer: C. multiple proportion

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

6. 6.

   MgO does not readily dissolve in water because

   1. A.of its high melting point
   2. B.it is a covalent compound
   3. C.it forms a hydroxide when dissolved in water
   4. D.its lattice energy is higher than its hydration energy

   Show answer

   Answer: D. its lattice energy is higher than its hydration energy

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

7. 7.

   Consider the reaction represented by the following equation: CuO$_{(s)}$ + H$_2$SO$_{4(aq)}$ → CuSO$_{4(aq)}$ + H$_2$O$_{(l)}$. Which of the following factors will not affect the rate of the reaction?

   1. A.Particle size of CuO(s)
   2. B.Concentration of H2SO4(aq)
   3. C.Temperature of the reacting mixture
   4. D.Pressure of reaction system

   Show answer

   Answer: D. Pressure of reaction system

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

8. 8.

   The postulate that molecules are in constant random motion best explains why liquids

   1. A.can undergo solidification
   2. B.maintain their volumes
   3. C.are incompressible
   4. D.have no characteristic shape

   Show answer

   Answer: D. have no characteristic shape

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

9. 9.

   Which of the following ions has an electron configuration different from the other?

   1. A.17CI-
   2. B.8O2-
   3. C.12Mg2+
   4. D.13AI3+

   Show answer

   Answer: A. 17CI-

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

10. 10.

    Which of the following industrial processes depends on the action of enzymes?

    1. A.Liquefaction of air
    2. B.Manufacture of soap
    3. C.Brewing of beer
    4. D.Catalytic cracking

    Show answer

    Answer: C. Brewing of beer

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

11. 11.

    The shape of a graphite crystal is

    1. A.tetrahedral
    2. B.pyramidal
    3. C.hexagonal
    4. D.octahedral

    Show answer

    Answer: C. hexagonal

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

12. 12.

    Which of the following statements about a radioactive substance is/are correct? l. lt emits radiation continuously and spontaneously. ll. The emitted radiations are affected by temperature and pressure III. The radiation can penetrate opaque matter

    1. A.ll only
    2. B.l and ll only
    3. C.l and lll only
    4. D.ll and lll only

    Show answer

    Answer: C. l and lll only

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

13. 13.

    A sample of a gas may be identified as chlorine if it turns

    1. A.damp blue litmus paper red
    2. B.lime water miky
    3. C.lead ethanoate paper black
    4. D.starch iodide paper blue-black

    Show answer

    Answer: D. starch iodide paper blue-black

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

14. 14.

    Which of the following electron configurations represents that of an atom in its ground state?

    1. A.1s 22s12p1
    2. B.1s22s22p63s13p1
    3. C.1s22s12p3
    4. D.1s22s22p63s0

    Show answer

    Answer: D. 1s22s22p63s0

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

15. 15.

    The oxidation number of Fe in [Fe(CN)$_6$]$^{3-}$ is

    1. A.+3
    2. B.+2
    3. C.-2
    4. D.-3

    Show answer

    Answer: A. +3

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

16. 16.

    A metal that is widely used in the manufacture of paints and overhead electric cables is

    1. A.aluminium
    2. B.copper
    3. C.iron
    4. D.lead

    Show answer

    Answer: A. aluminium

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

17. 17.

    A tertiary alkanol has a molecular formula C$_4$H$_{10}$O. What is the structural formula of the compound?

    1. A.(CH 3)2CHCH2OH
    2. B.CH3CH2CH(OH)CH3
    3. C.(CH3)3COH
    4. D.CH3CH2CH2CH2OH

    Show answer

    Answer: C. (CH3)3COH

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

18. 18.

    Consider the reaction represented by the following equation: xCH$_3$OH + yO$_2$ → 2CO$_2$ + zH$_2$O. The values of x,y and z respectively, are

    1. A.2,3 and 4
    2. B.2, 4 and 3
    3. C.1,2 and 3
    4. D.1, 3 and 5

    Show answer

    Answer: A. 2,3 and 4

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

19. 19.

    Two elements, X and Y are in the same group on the periodic table because they both have the same

    1. A.number of electronic shells
    2. B.number of valence electrons
    3. C.atomic size
    4. D.atomic number

    Show answer

    Answer: B. number of valence electrons

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

20. 20.

    Consider the following reaction equation: C$_{16}$H$_{34}$ → C$_5$H$_{12}$ + C$_{11}$H$_{22}$. The process represented by the equation is

    1. A.cracking
    2. B.fermentation
    3. C.polymerization
    4. D.reforming

    Show answer

    Answer: A. cracking

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

21. 21.

    Brass is a mixture of

    1. A.Cu and Sn
    2. B.Cu and Zn
    3. C.Cu and Mg
    4. D.Cu and Pb

    Show answer

    Answer: B. Cu and Zn

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

22. 22.

    Which of the following metals would readily displace hydrogen from steam?

    1. A.Copper
    2. B.Lead
    3. C.Magnesium
    4. D.Silver

    Show answer

    Answer: C. Magnesium

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

23. 23.

    Which of the following substances is mainly responsible for the depletion of the ozone layer?

    1. A.Oxgyen
    2. B.Chlorofluorocarbon
    3. C.Carbon (ll) oxide
    4. D.Nitrogen (ll) oxide

    Show answer

    Answer: B. Chlorofluorocarbon

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

24. 24.

    When a substance changes directly from the solid state to the gaseous state without forming a liquid, the substance is said to

    1. A.condense
    2. B.evaporate
    3. C.sublime
    4. D.precipitate

    Show answer

    Answer: C. sublime

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

25. 25.

    Which of the following gases has the lowest rate of diffusion under the same condition? [H = 1.00; He = 4. 00; O = 16.0; CI = 35.5]

    1. A.CI2
    2. B.H2
    3. C.He
    4. D.O2

    Show answer

    Answer: A. CI2

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

26. 26.

    The vapour pressure of a liquid depends on l. temperature. ll. rate of condensation. III. cohesive forces holding the particles together

    1. A.l only
    2. B.l and ll only
    3. C.l and lll only
    4. D.ll and lll only

    Show answer

    Answer: C. l and lll only

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

27. 27.

    Consider the following reaction equation: CaCO$_{3(s)}$ + 2HCI$_{(aq)}$ → CaCl$_{2(aq)}$ + H$_2$O$_{(l)}$ + CO$_{2(g)}$. What mass of CaCI$_2$ would be obtained when 25.0g of CaCO$_{3(s)}$ is reacted with excess HCI$_{(aq)}$? [CaCO$_3 = 100; CaCI$_2$ = 111]

    1. A.4.00g
    2. B.4.44 g
    3. C.18.9 g
    4. D.27.8 g

    Show answer

    Answer: D. 27.8 g

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

28. 28.

    The number of sulphur atoms in 3.20g of SO$_{2(g)}$ is [O = 16.0;S = 32.0; Avogadro constant = 6.02 x 10$^{23}$]

    1. A.3.01 x 1022
    2. B.6.02 x 1022
    3. C.6.02 x1023
    4. D.1.20 x 1024

    Show answer

    Answer: A. 3.01 x 1022

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

29. 29.

    Which of the following pH values indicates that a solution is a strong base?

    1. A.1
    2. B.5
    3. C.9
    4. D.13

    Show answer

    Answer: D. 13

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

30. 30.

    The volume occupied by 0.4 g of hydrogen gas at s.t.p. is [H = 1. 00; Molar volume at s.t.p. = 22.4 dm3]

    1. A.2.24 dm3
    2. B.4.48dm3
    3. C.22.4dm3
    4. D.44.8dm 3

    Show answer

    Answer: B. 4.48dm3

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

31. 31.

    The number of orbitals in a p-sub level of an atom is

    1. A.2
    2. B.3
    3. C.5
    4. D.6

    Show answer

    Answer: B. 3

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

32. 32.

    The complex compound formed when aluminum dissolves in aqueous sodium hydroxide is

    1. A.Na3Al(OH)4.
    2. B.NaAl(OH)4
    3. C.NaAl(OH)3
    4. D.Na2Al(OH)3

    Show answer

    Answer: B. NaAl(OH)4

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

33. 33.

    On heating, the following trioxocarbonate (IV) salts decompose to give solid residue except

    1. A.ammonium trioxocarbonate (IV)
    2. B.calcium trioxocarbonate (IV)
    3. C.lead (ll) trioxocarbonate(IV)
    4. D.zinc trioxocarbonate (IV)

    Show answer

    Answer: A. ammonium trioxocarbonate (IV)

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

34. 34.

    The atomic radii of metals are usually

    1. A.greater than their ionic radii
    2. B.equal to their ionic radii
    3. C.less than their ionic radii
    4. D.less than those of non-metals in the same period

    Show answer

    Answer: A. greater than their ionic radii

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

35. 35.

    A spot of oil paint on a shirt can best be removed using?

    1. A.brine
    2. B.detergent
    3. C.kerosine
    4. D.warm water

    Show answer

    Answer: C. kerosine

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

36. 36.

    The hydrolysis of NH$_4$CI gives

    1. A.an acidic solution
    2. B.an alkaline solution
    3. C.a buffer solution
    4. D.a neutral solution

    Show answer

    Answer: A. an acidic solution

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

37. 37.

    The complex compound formed by the combination of two elements with a large electronegativity difference is likely to be

    1. A.polar covalent
    2. B.giant molecular
    3. C.covalent
    4. D.ionic

    Show answer

    Answer: D. ionic

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

38. 38.

    A substance L reacts with NH$_4$NO$_{3(aq)}$ to generate ammonia gas. L is likely to be

    1. A.HCl
    2. B.NaOH
    3. C.CH3COOH
    4. D.CaSO4

    Show answer

    Answer: B. NaOH

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

39. 39.

    The formula of mercury (l) dioxonitrate (III) is

    1. A.HgNO3
    2. B.Hg2NO2
    3. C.Hg2(NO2)2
    4. D.Hg(NO3)2

    Show answer

    Answer: C. Hg2(NO2)2

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

40. 40.

    Which of the following substances would not produce ethanol when fermented?

    1. A.Cane sugar
    2. B.Glucose
    3. C.Starch
    4. D.Vinegar

    Show answer

    Answer: D. Vinegar

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

41. 41.

    An alkanol can be prepared by the reaction of an alkene with

    1. A.concentrated tetraoxosulphate (VI) acid
    2. B.bromine tetrachloroethane
    3. C.aqueous potassium tetraoxomanganate (VII)
    4. D.sodium hydroxide solution

    Show answer

    Answer: A. concentrated tetraoxosulphate (VI) acid

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

42. 42.

    The energy evolved when magnesium burns in air is in the form of

    1. A.heat
    2. B.heat and sound
    3. C.light and heat
    4. D.sound

    Show answer

    Answer: C. light and heat

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

43. 43.

    Which of the following elements is a metalloid?

    1. A.Carbon
    2. B.Oxygen
    3. C.Silicon
    4. D.Sodium

    Show answer

    Answer: C. Silicon

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

44. 44.

    Which of the following pollutants is not usually recycled?

    1. A.Aluminium cans
    2. B.Glass bottles
    3. C.Nuclear wastes
    4. D.Paper wastes

    Show answer

    Answer: C. Nuclear wastes

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app