WAEC - Chemistry (1990)

  • 1
    Catalytic hydrogenation of oils results in the production of
    답변
    (E)
    margarine
  • 2
    Which of the following reaction will not take place under normal conditions?
    답변
    (C)
    Cu (s) + 2HCI (aq) → CuCI 2(aq) + H2(g)
  • 3
    A sample of orange juice is suspected to have been contaminated with a yellow dye. Which of the following methods can be used to detect the dye?
    답변
    (B)
    Chromatography
  • 4
    The electronic configuration 1s2 22s 22p 63s23p 6 is that of a
    답변
    (A)
    noble gas
  • 5
    The heat accompanying the reaction represented by the equation H2O (l) → H 2O(g) is described as the heat of
    답변
    (C)
    vaporization
  • 6
    Aluminum is above iron in the electrochemical series, yet iron corrodes easily on exposure to air while aluminium does not. This is because aluminium
    답변
    (D)
    forms thin layer of inert oxide in moist air
  • 7
    When a solid melts and consequently boils, there is
    답변
    (A)
    a gradual increase in the average kinetic energy of the particles
  • 8
    Which of the following compounds will undergo additional reactions?
    답변
    (A)
    Ethyne
  • 9
    Which of the following reactions does not occur in the blast furnace during the extraction of iron?
    답변
    (E)
    2Fe2O(s) → 4Fe(l) 3O2(g)
  • 10
    A catayst which increases the rate of a chemical reaction does so by
    답변
    (E)
    decreasing the activation energy of the reaction
  • 11
    How many molecules are there in 14g of nitrogen gas at s.t.p? (n = 14, Avogadro Number = 6. 0 x \(10^{23 }\)mol-1)
    답변
    (B)
    3.0 x 1023
  • 12
    Which of the following correctly explains entropy?
    답변
    (A)
    the natural tendency for a system to achieve a greater disorder
  • 13
    The gas that is liberated when iron is heated with concentrated tetraoxosulphate (VI)acid is
    답변
    (B)
    \(SO_{2}\)
  • 14
    Which of the following salts in aqueous solution will have a pH greater than 7?
    답변
    (E)
    K 2CO3
  • 15
    The compound of copper which is used in electroplating dyeing, printing, wood preservation and as a fungicide is
    답변
    (C)
    copper (ll) tetraoxosulphate (VI) pentahydrate
  • 16
    What is the molecular formula of a compound whose empirical formula is CH2O and molar mass is 180? (H = 1, C = 12, O = 16)
    답변
    (D)
    C 6H 12O6
  • 17
    MO and X 2O represent the formula of oxides of elements M and X respectively . If M and X should combine to form a separate compound, what would be the formula of the compound?
    답변
    (A)
    MX2
  • 18
    Which of the following pollutants is biodegradable ?
    답변
    (A)
    Sewage
  • 19
    In the reaction represented by the equation; 2FeCI3 + SO2 + 2H2O → 2FeCL2 + H2SO4 + 2HCI the oxidation number of sulphur changes from
    답변
    (B)
    + 4 to + 6
  • 20
    Which of the following equations represents the reaction leading to the removal of permanent hardness of water?
    답변
    (B)
    MgSO4 + Na 2CO3 + Na 2SO
  • 21
    The following alloys contain copper except
    답변
    (A)
    magnalium
  • 22
    How many mole of AgNO\(_3\) are there in 500cm\(^3\) of 0.01M AgNO\(_3\) solution?
    답변
    (A)
    0.005 mole
  • 23
    Which of the following statements explains why tetraoxosulphate (IV) acid is reqarded as a strong acid?
    답변
    (C)
    the acid is complately ionized in aqueous solution
  • 24
    Which of the following is not correct of glucose and fructose?They
    답변
    (C)
    can be obtained by the hydrolysis of starch
  • 25
    To what temperature must a gas be raised from 273K in order to double both its volume and pressure?``
    답변
    (E)
    1092k
  • 26
    Which of the following explains why trioxonitrate (V) acid is not used for preparing hydrogen from metals?
    답변
    (B)
    it is strongly oxidizing
  • 27
    Which of the following is normally used for drying ammonia gas?
    답변
    (B)
    Calcium oxide
  • 28
    Nuclear reactions can be used in the following except
    답변
    (E)
    purifying water
  • 29
    The decomposition of hydrogen peroxide is represented by the equation: 2H2O(l) + O2(g) what mass of hydrogen peroxide would be required to produce 22.4dm3 of oxygen at s.t.p? (H = 1, O = 16, molar volume of a gas at s.t.p. = 22.4dm3)
    답변
    (E)
    68 g
  • 30
    Which of the following compounds crystallizes without water of crystallization?
    답변
    (D)
    NaCI