WAEC - Chemistry (1990)

  • 1
    Catalytic hydrogenation of oils results in the production of
    پاسخ دهید
    (E)
    margarine
  • 2
    Which of the following reaction will not take place under normal conditions?
    پاسخ دهید
    (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?
    پاسخ دهید
    (B)
    Chromatography
  • 4
    The electronic configuration 1s2 22s 22p 63s23p 6 is that of a
    پاسخ دهید
    (A)
    noble gas
  • 5
    The heat accompanying the reaction represented by the equation H2O (l) → H 2O(g) is described as the heat of
    پاسخ دهید
    (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
    پاسخ دهید
    (D)
    forms thin layer of inert oxide in moist air
  • 7
    When a solid melts and consequently boils, there is
    پاسخ دهید
    (A)
    a gradual increase in the average kinetic energy of the particles
  • 8
    Which of the following compounds will undergo additional reactions?
    پاسخ دهید
    (A)
    Ethyne
  • 9
    Which of the following reactions does not occur in the blast furnace during the extraction of iron?
    پاسخ دهید
    (E)
    2Fe2O(s) → 4Fe(l) 3O2(g)
  • 10
    A catayst which increases the rate of a chemical reaction does so by
    پاسخ دهید
    (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)
    پاسخ دهید
    (B)
    3.0 x 1023
  • 12
    Which of the following correctly explains entropy?
    پاسخ دهید
    (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
    پاسخ دهید
    (B)
    \(SO_{2}\)
  • 14
    Which of the following salts in aqueous solution will have a pH greater than 7?
    پاسخ دهید
    (E)
    K 2CO3
  • 15
    The compound of copper which is used in electroplating dyeing, printing, wood preservation and as a fungicide is
    پاسخ دهید
    (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)
    پاسخ دهید
    (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?
    پاسخ دهید
    (A)
    MX2
  • 18
    Which of the following pollutants is biodegradable ?
    پاسخ دهید
    (A)
    Sewage
  • 19
    In the reaction represented by the equation; 2FeCI3 + SO2 + 2H2O → 2FeCL2 + H2SO4 + 2HCI the oxidation number of sulphur changes from
    پاسخ دهید
    (B)
    + 4 to + 6
  • 20
    Which of the following equations represents the reaction leading to the removal of permanent hardness of water?
    پاسخ دهید
    (B)
    MgSO4 + Na 2CO3 + Na 2SO
  • 21
    The following alloys contain copper except
    پاسخ دهید
    (A)
    magnalium
  • 22
    How many mole of AgNO\(_3\) are there in 500cm\(^3\) of 0.01M AgNO\(_3\) solution?
    پاسخ دهید
    (A)
    0.005 mole
  • 23
    Which of the following statements explains why tetraoxosulphate (IV) acid is reqarded as a strong acid?
    پاسخ دهید
    (C)
    the acid is complately ionized in aqueous solution
  • 24
    Which of the following is not correct of glucose and fructose?They
    پاسخ دهید
    (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?``
    پاسخ دهید
    (E)
    1092k
  • 26
    Which of the following explains why trioxonitrate (V) acid is not used for preparing hydrogen from metals?
    پاسخ دهید
    (B)
    it is strongly oxidizing
  • 27
    Which of the following is normally used for drying ammonia gas?
    پاسخ دهید
    (B)
    Calcium oxide
  • 28
    Nuclear reactions can be used in the following except
    پاسخ دهید
    (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)
    پاسخ دهید
    (E)
    68 g
  • 30
    Which of the following compounds crystallizes without water of crystallization?
    پاسخ دهید
    (D)
    NaCI