WAEC Chemistry questions

357 questions with answers and explanations. Tap an option to check yourself.

1. Question 141· Electrolysis· WAEC

   During electrolysis, positive ions move towards the

   • Aanode
   • Belectrolyte surface
   • Ccathode
   • Dbattery

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2. Question 142· Electrolysis· WAEC

   A substance that conducts electricity when molten or in solution and is decomposed by it is

   • Aa metal
   • Ba non-electrolyte
   • Can electrolyte
   • Dan insulator

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3. Question 143· Electrolysis· WAEC

   How many faradays are needed to deposit one mole of aluminium from Al³⁺ ions?

   • A1
   • B3
   • C2
   • D27

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4. Question 144· Electrolysis· WAEC

   The quantity of electricity passed when 2 A flows for 965 s is

   • A965 C
   • B1,930 C
   • C482.5 C
   • D3,860 C

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5. Question 145· Electrolysis· WAEC

   Which of these conducts electricity by the movement of ions?

   • Aa copper wire
   • Bmolten lead(II) bromide
   • Ca graphite rod
   • Dsolid sodium chloride

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6. Question 146· Electrolysis· WAEC

   In electrolysis, the cathode is the electrode

   • Aconnected to the positive terminal
   • Bwhere oxidation occurs
   • Cconnected to the negative terminal, where reduction occurs
   • Dthat always dissolves

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7. Question 147· Electrolysis· WAEC

   Very dilute sodium chloride solution is electrolysed with inert electrodes. The main gas at the anode is

   • Ahydrogen
   • Bchlorine
   • Csodium
   • Doxygen

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8. Question 148· Energy changes· WAEC

   Which combination makes a reaction spontaneous (ΔG negative) at every temperature?

   • Apositive ΔH and negative ΔS
   • Bnegative ΔH and positive ΔS
   • Cpositive ΔH and positive ΔS
   • Dnegative ΔH and negative ΔS

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9. Question 149· Energy changes· WAEC

   Dissolving ammonium chloride in water makes the beaker feel cold. The process is

   • Aa neutralisation
   • Bexothermic
   • Ca redox reaction
   • Dendothermic

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10. Question 150· Energy changes· WAEC

    The heat of combustion of a substance is the heat

    • Aevolved when one mole burns completely in oxygen
    • Babsorbed when one mole melts
    • Cevolved on dissolving
    • Dneeded to boil one mole

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11. Question 151· Energy changes· WAEC

    Dissolving ammonium nitrate in water makes the solution cold because the process is

    • Aa combustion
    • Bexothermic
    • Cendothermic
    • Dneutralisation

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12. Question 152· Energy changes· WAEC

    A reaction in which heat is absorbed from the surroundings is

    • Areversible
    • Bexothermic
    • Ccatalytic
    • Dendothermic

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13. Question 153· Energy changes· WAEC

    50 cm³ of 1.0 mol/dm³ HCl is mixed with 50 cm³ of 1.0 mol/dm³ NaOH and 2.85 kJ of heat is released. Find the heat of neutralisation.

    • A−114 kJ/mol
    • B−2.85 kJ/mol
    • C−28.5 kJ/mol
    • D−57 kJ/mol

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14. Question 154· Energy changes· WAEC

    When ammonium chloride dissolves in water, the solution becomes cold. The process is

    • Aexothermic
    • Bneutralisation
    • Cendothermic
    • Dcombustion

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15. Question 155· Energy changes· WAEC

    In an exothermic reaction, the energy of the products is

    • Aless than that of the reactants
    • Bgreater than that of the reactants
    • Cequal to that of the reactants
    • Dzero

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16. Question 156· Energy changes· WAEC

    Burning butane in a gas cooker is described as exothermic because

    • Ait needs a spark to start
    • Bheat is absorbed from the surroundings
    • Cheat is given out to the surroundings
    • Dthe products are gases

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17. Question 157· Energy changes· WAEC

    Heat released when 2 mol of a substance burns is 1,600 kJ. Find the heat of combustion per mole.

    • A−1,600 kJ/mol
    • B−800 kJ/mol
    • C−3,200 kJ/mol
    • D+800 kJ/mol

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18. Question 158· Energy changes· WAEC

    An energy profile diagram where the products are higher in energy than the reactants represents

    • Aa neutral reaction
    • Ban exothermic reaction
    • Can endothermic reaction
    • Da catalysed reaction only

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19. Question 159· Energy changes· WAEC

    A reaction that gives out heat to the surroundings is

    • Aendothermic
    • Bexothermic
    • Creversible
    • Dcatalytic

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20. Question 160· Energy changes· WAEC

    Activation energy is the

    • Aenergy released by a reaction
    • Bminimum energy needed for a reaction to occur
    • Cheat of solution
    • Dbond length

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