WAEC 2012 Chemistry Questions and Answer

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Your results on CHEMISTRY 2012 are shown below

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

  • 2.
  • 3.
  • 5.
  • 6.

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

  • 1s2 2s2 2p6 3s1 3p1.
  • 1s2 2s1 2p1.
  • 1s2 2s1 2p3.
  • 1s2 2s2 2p6 3s0

3. A beam of particles was passed between charged plates as illustrated in the diagram below X, Y and Z are respectively

  • electron, neutron and proton.
  • electron, proton and neutron.
  • proton, neutron and electron.
  • proton, electron and neutron.

4. The atomic radii of metals are usually

  • greater than their ionic radii.
  • equal to their ionic radii.
  • less than their ionic radii.
  • less than those of non-metals in the same period.

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

  • number of electronic shells.
  • number of valence electrons.
  • atomic size.
  • atomic number.

6. The cf-block elements are paramagnetic because they

  • contain paired electrons which are repelled by magnetic field.
  • contain unpaired electrons in the partially filled 3d-orbital.
  • form coloured complex ions that attract magnetic lines of force.
  • have delocalized valence electrons.

7. Which of the following statements about a radioactive substance is/are correct?

I. It emits radiation continuously and spontaneously. II The emitted radiations are affected by temperature and pressure. III. The radiation can penetrate opaque matter.

  • II only.
  • I and II only.
  • I and III only.
  • II and III only.

8. Which of the following elements is a metalloid?

  • Carbon.
  • Oxygen.
  • Silicon.
  • Sodium.

9. Which of the following halogens is liquid at room temperature?

  • Chlorine.
  • Fluorine.
  • Iodine.
  • Bromine.

10. The shape of a graphite crystal is

  • tetrahedral.
  • pyramidal.
  • hexagonal.
  • octahedral.

11. The compound formed by tne combination of two elements with a large electronegativity difference is likely to be

  • polar covalent.
  • giant molecular.
  • covalent.
  • ionic.

12. The complex compoud formed when aluminium dissolves in aqueous sodium hydroxide is

  • Na3AL(OH)4.
  • NaAL(OH)4.
  • NaAL(OH)3.
  • Na2AL(OH)3.

13. The vapour pressure of a liquid depends on

  • temperature. II. rate of condensation. III. cohesive forces holding the particles together.
  • I only.
  • I and II only.
  • I and III only.
  • II and III only.

14. MgO does not readily dissolve in water because

  • of its high melting point.
  • it is a covalent compound.
  • it forms a hydroxide when dissolved in water.
  • its lattice energy is higher than its hydration energy.

15. Consider the following reaction equation:

CaCO3(s) + 2HCl(aq) â†’ CaCl2(aq) + H2O(l) + CO2(g)

What mass of CaCl2(aq)  would be obtained when 25.0g CaCO3(s) of is reacted with excess HCl(aq)?

[ CaCO3 = 100,  CaCl2 = 111]

  • 18.9 g.
  • 4.00 g.
  • 4.44 g.
  • 18.9g.

16. The number of sulphur atoms in 3.20g of S02(g) is [O= 16.0;S = 32.0; Avogadro constant = 6.02 X 1023]

  • 3.01 x 1022.
  • 6.02 x 1022.
  • 6.02 x 1023.
  • 1.20 x 1024

17. Consider the reaction represented by the following equation:

xCH3OH + yO2 â†’ 2CO2 + zH2

The values of x, y and z respectively are

  • 1, 3 and 5.
  • 2, 3 and 4.
  • 2, 4 and 3.
  • 1, 2 and 3.

18. 19. The formula of mercury (I) dioxonitrate (III) is

  • HgN03.
  • Hg2N02.
  • Hg2(N02)2.
  • Hg(N03)2.

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

  • damp blue litmus paper red.
  • lime water milky.
  • lead ethanoate paper black.
  • starch iodide paper blue-black.

20. A metal M forms two types of chlorine, MCL2 and MCL3. Which of the following laws best explains the relationship between the chlorides? Law of

  • reciprocal proportion.
  • conservation of mass.
  • definite proportion.
  • multiple proportion.
  •  

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

  • Copper.
  • Lead.
  • Magnesium.
  • Silver.

22. 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 dm2]

  • 2.24 dm2.
  • 4.48 dm2.
  • 22.4 dm2.
  • 44.8 dm2.

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

  • condense.
  • evaporate.
  • sublime.
  • precipitate.

24. At ordinary temperature H20 is a liquid while HS is a gas. This is because H20 has

  • weak intermolecular forces holding its molecules together.
  • strong hydrogen bonds holding its molecules together.
  • induced dipole-induced dipo-^ forces between its molecules.
  • ionic forces between its molecules.

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

  • can undergo solidification.
  • maintain their volumes.
  • are incompressible.
  • have no characteristic shape.

26. Which of the following gases has the lowest rate of diffusion under the same condition? [H = 1.00; He = 4.00; O = 16.0; Cl = 35.5]

  • Cl2.
  • H2.
  • He.
  • O2.

27. A substance L reacts with NH4NO3(aq) to generate ammonia gas. L is likely to be

  • HCL.
  • NaOH.
  • CH3COOH.
  • CaS04.

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

  • ich of the following pH values indicates that a solution is a strong base?
  • 1.
  • 5.
  • 9.
  • 13.

29. The hydrolysis of NH4CL gives

  • an acidic solution.
  • an alkaline solution.
  • a buffer solution.
  • a neutral solution.

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

  • brine.
  • detergent.
  • kerosine.
  • warm water.

31. Consider the following solubility curves.

Which of the following deductions could be correctly made from the graph?

  • S is least soluble among the salts.
  • The solubility of U is not affected by change in temperature.
  • The solubility of S decreases with increasing temperature.
  • T is most soluble among the salts.

32. Consider the reaction represented by the following equation:

CuO(s) + H2SO4(aq) â†’ CuSO4(aq) + H2O(l)

Which of the following factors will not affect the rate of the reaction?

  • Particle size of CuO(s).
  • Concentration of H2SO4 (aq).
  • Temperature of the reacting mixture
  • Pressure of the reaction.

33. Use the following graph to answer questions 36 and 37

The activation energy of the reaction is

  • 120kJ.
  • 40 kJ.
  • 60 kJ.
  • 80 kJ.
  •  

34. The type of reaction represented by the graph is

  • endothermic.
  • exothermic.
  • catalytic.
  • spontaneous.

35. Which of the following devices function on redox reaction? I. Dry cell II. Car cattery III. Electric generator

  • I and III only.
  • II and III only.
  • I and II only.
  • I, II and III.

36. The oxidation number of Fe in [ Fe (CN)]3 is

  • +3.
  • +2.
  • -2.
  • -3.

37. Consider the following reaction equation:

C16H34 â†’ C5H12 + C11H22

The process represented by the equation is called

  • cracking
  • fermentation
  • polymerization
  • reforming

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

  • Cane sugar.
  • Glucose.
  • Starch.
  • Vinegar.

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

  • concentrated tetraoxosulphate (VI) acid.
  • bromine in tetrachloroethane.
  • aqueous potassium tetraoxomanganate (VII).
  • sodium hydroxide solution.

40. A compound contains 7.75% hydrogen, 37.21% carbon and 55.04% chlorine.

  • C5H2CL.
  • C3H3CL.
  • C2H5CL.
  • C3H8CL.

41. A tertiary alkanol has a molecular formula C4H10O. What is the structural formula of the compound?

  • (CH3)2CHCH2OH.
  • CH3CH2CH(OH)CH3.
  • (CH3)3COH.
  • CH2CH2CH2CH20H.

42. Which of the following industrial processes depends on the action of enzymes

  • Liquefaction of air.
  • Manufacture of soap.
  • Brewing of beer.
  • Catalytic cracking.

43. Which of the following pottutants is not usually recycled?

  • Aluminium cans.
  • Glass bottles.
  • Nuclear wastes.
  • Paper wastes.

44. A metal that is widely used in the manufacture of paints and overhead electnc cables is

  • aluminium.
  • copper.
  • iron.
  • lead.

45. Brass is a mixture of

  • Cu and Sn.
  • Cu and Zn.
  • Cu and Mo.
  • Cu and Pb.

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

  • Oxygen.
  • Chlorofluorocarbon.
  • Carbon (ii) oxide.
  • Nitrogen (ii) oxide.

47. Consider the following structures of organic compounds

Which of the following statements about the structure is not correct?

  • They are geometric isomers
  • They are saturated hydrocarbons
  • They have similar physical properties
  • They are members of the same homologous series

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

  • heat
  • heat and sound
  • light and heat
  • sound

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

  • 1
  • 5
  • 9
  • 13

50. Which of the following devices function on redox reaction?

I. Dry cell II. Car battery III. Electric generator

  • I and III only
  • II and III only
  • I and II only
  • I, II and III

ANSWERS

  1. B
  2. D
  3. C
  4. C
  5. B
  6. B
  7. D
  8. A
  9. D
  10. C
  11. D
  12. B
  13. B
  14. D
  15. –
  16. B
  17. B
  18. B
  19. D
  20. D
  21. C
  22. B
  23. A
  24. B
  25. A
  26. A
  27. B
  28. A
  29. A
  30. B
  31. B
  32. D
  33. A
  34. B
  35. C
  36. A
  37. A
  38. D
  39. A
  40. C
  41. C
  42. C
  43. –
  44. A
  45. B
  46. B
  47. B
  48. C
  49. A
  50. C

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