WAEC - Chemistry (2020)

  • 1
    Which of the following substances is an example of a fine chemical?
    Atsakymas
    (C)
    Ethylene
  • 2

     

    The IUPAC name of the compound represented by the structure below is ?








     

    Atsakymas
    (A)
    2- chloro but-I ,3-diene.
  • 3
    Which or the following substances is a polypeptide?
    Atsakymas
    (C)
    Protein
  • 4

    Which or the following products could be formed during incomplete combustion of a hydrocarbon.

    i.Carbon ii. Hydrogen III. Carbon (Il) oxide

    Atsakymas
    (C)
    I and III only
  • 5
    What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ?
    Atsakymas
    (B)
    3 moles
  • 6

    What is the mass of silver deposited when 24,125 C of electricity is passed through a solution or silver salt.

    [Ag = 108, IF = 96,500 C ]

    Atsakymas
    (D)
    27g
  • 7
    Equal masses of calcium trioxocarbonate(iv) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest?
    Atsakymas
    (A)
    Calcium trioxocarbonate ( iv ) chips a 20°C
  • 8
    The high solubility of ethanol in water is due to?
    Atsakymas
    (D)
    hydrogen bonding
  • 9
    Which of the following pairs of properties of alkali metals decreases down the group?
    Atsakymas
    (D)
    First ionization energy and melting point
  • 10
    The most suitable process of obtaining water from an aqueous solution of sugar i
    Atsakymas
    (B)
    Distillation
  • 11
    Group VIl elements in their combined states are called?
    Atsakymas
    (C)
    Halide
  • 12
    When an ionic bond is broken, bonding electrons are
    Atsakymas
    (B)
    gained by the most electropositive atom
  • 13
    The oxidation state of chlorine in NaClO\(_3\) is?
    Atsakymas
    (C)
    +5
  • 14
    A balanced chemical equation is based on the law of?
    Atsakymas
    (D)
    Conservation of mass
  • 15
    Which of the following pairs of elements has the greatest difference in electronegativity?
    Atsakymas
    (A)
    Na and F
  • 16
    A factor that is considered most important when siting a chemical industry is?
    Atsakymas
    (B)
    nearness to raw materials
  • 17
    The boiling point of pentane is higher than that of propane because?
    Atsakymas
    (B)
    Pentane has more covalent bonds to break
  • 18
    Which of the following solids would not decompose on heating?
    Atsakymas
    (C)
    Potassium trioxocarbonate (IV)
  • 19
    The following molecules have double covalent bonds between two atoms except?
    Atsakymas
    (D)
    water
  • 20
    The type of isomerism exhibited by cis and trans isomers is?
    Atsakymas
    (B)
    geometrical
  • 21
    Which of the following compounds has the lowest boiling point?
    Atsakymas
    (A)
    C\(_4\)H\(_10\)
  • 22
    An alkanol containing 60% carbon by mass would have a molecular formula [H=1.0. C-12.0, O= 16.0]
    Atsakymas
    (C)
    C\(_3\)H\(_7\)OH
  • 23

    Which of the following compounds would release hydrogen when reacted with sodium metal? 

    I. CH\(_3\)COOH

    II. CH\(_3\)CH\(_2\)OH

    III. CH\(_3\)COOCH\(_3\)

    Atsakymas
    (B)
    I and II only
  • 24
    Which of the following substances is not a reducing agent?
    Atsakymas
    (C)
    O\(_2\)
  • 25
    Which of the following statements is correet for a reaction at equilibrium?
    Atsakymas
    (C)
    The rates of the forward and backward reactions are equal
  • 26
    Which of the following reactions are always exothermic? 1. Neutralization Il. Decomposition III. Combustion
    Atsakymas
    (B)
    I and III only
  • 27
    Which of the following standard conditions is not correct about energy changes?
    Atsakymas
    (D)
    ΔH at 298 K is the activation energy
  • 28
    f 5.0 cm\(^-3\) of 0.200 mol dm(^-3\) Na\(_2\)CO\(_3\) was diluted to 250cm(^-3\) solution, what would be the concentration of the resulting solution?
    Atsakymas
    (A)
    0.004 mol dm(^-3\)
  • 29
    The initial volume and pressure of a given mass of gas is V and 3.P. What is its pressure if its volume is increased to  2V at constant temperature?
    Atsakymas
    (C)
    \(frac{3}{2}\) P
  • 30

    What volume of oxygen at s.t.p is required to burn completely 7.5 dm\(^3\) of methane according to the following equation?

    CH\(_4\) \(_g\) + 20\(_2\) \(_g\) → CO\(_2\) \(_g\) + H\(_2\)O\(_g\)

    Atsakymas
    (C)
    15.0 dm\(^3\)
  • 31

    When 250 cm3 of a saturated solution of CuSO\(_4\) at 30°C was evaporated to dryness, 5.0 g of the salt was obtained..

    What is the solubility of the salt at 30°C? [CuSO\(_4\) = 160]

    Atsakymas
    (B)
    0.125
  • 32
    The bond between NH\(_3\) and H\(^+\) in NH4\(^+\) is?
    Atsakymas
    (A)
    dative
  • 33
    Which of the following oxides has a giant covalent structure?
    Atsakymas
    (D)
    SiO\(_2\)
  • 34
    Which of the following hydroxides is not readily soluble in water?
    Atsakymas
    (B)
    Ca(OH)\(_2\)
  • 35
    Which of the following statements about the solubility of a salt is correct?
    Atsakymas
    (C)
    Crystallization would be efficient in separating out a salt whose solubility increases considerably with temperature
  • 36
    How many moles of H\(_2\)SO4 are there in 50 cm\(^3\) of 0.108 mol dm\(^3\) solution of the acid?
    Atsakymas
    (B)
    5.4 x 10\(^{-3}\)
  • 37
    If 20 cm\(^3\) of sodium hydroxide was neutralized by 20 cm\(^3\) of 0.01 mol dm\(^3\) tetraoxosulphate(VI) acid, what is the concentration of the sodium hydroxide solution?
    Atsakymas
    (B)
    0.020
  • 38
     "Electrons always occupy the lowest empty energy level" is a statement of
    Atsakymas
    (A)
    Aufbau Principle
  • 39
    Which of the following metals does not react with water to produce hydrogen?
    Atsakymas
    (A)
    Copper
  • 40
    Which of the following arrangement of elements is in decreasing order of electronegativity?
    Atsakymas
    (D)
    P, Si, Al, Mg, Na
  • 41
    The metallic bond in magnesium is stronger than that in calcium because magnesium has a
    Atsakymas
    (B)
    smaller atomic size
  • 42

    Consider the reaction represented by the following equation:

    AgNO\(_3\) + NaCl → AgCl + NaNO\(_3\).

    The steps that could be taken to obtain pure dry sample of AgCI (s) from the mixture includes

    Atsakymas
    (C)
    filtering, washing and drying
  • 43
    How many electrons does  \({31}_{15}\)P\(^3-\) contain?
    Atsakymas
    (D)
    18
  • 44
    The atomic number of an atom would be equal to its mass number if it
    Atsakymas
    (C)
    does not contain neutrons
  • 45
    Which of the following processes is not exhibited by atoms in order to attain more stable electron configuration?
    Atsakymas
    (B)
    Hybridization of orbitals