WAEC Chemistry questions

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

1. Question 21· Acids, bases and salts· WAEC

   Which indicator is most suitable for titrating a strong acid against a weak base?

   • Apotassium manganate(VII)
   • Bphenolphthalein
   • Cstarch
   • Dmethyl orange

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2. Question 22· Acids, bases and salts· WAEC

   An acid turns blue litmus paper

   • Acolourless
   • Bgreen
   • Cyellow
   • Dred

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3. Question 23· Acids, bases and salts· WAEC

   Zinc granules react with dilute hydrochloric acid to give

   • Azinc oxide and chlorine
   • Bzinc chloride and hydrogen
   • Czinc chloride and water
   • Dzinc hydroxide and hydrogen

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4. Question 24· Acids, bases and salts· WAEC

   Which salt is insoluble in water?

   • Abarium sulphate
   • Bsodium chloride
   • Cpotassium nitrate
   • Dammonium chloride

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5. Question 25· Acids, bases and salts· WAEC

   Pure water at 25 °C has a pH of

   • A14
   • B0
   • C7
   • D1

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6. Question 26· Acids, bases and salts· WAEC

   What volume of 0.1 mol/dm³ NaOH will exactly neutralise 25 cm³ of 0.1 mol/dm³ HCl?

   • A2.5 cm³
   • B50 cm³
   • C12.5 cm³
   • D25 cm³

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7. Question 27· Air· WAEC

   The components of air can be separated by

   • Achromatography
   • Bfiltration
   • Celectrolysis
   • Dfractional distillation of liquid air

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8. Question 28· Air· WAEC

   Noble gases are used in electric bulbs because they are

   • Aflammable
   • Bcoloured
   • Cunreactive
   • Ddense

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9. Question 29· Air· WAEC

   The gas in the air used for filling the space above food in packets to keep it fresh is

   • Ahydrogen
   • Boxygen
   • Cnitrogen
   • Dchlorine

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10. Question 30· Air· WAEC

    The gas in the air that causes iron to rust together with water is

    • Anitrogen
    • Boxygen
    • Cargon
    • Dneon

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11. Question 31· Air· WAEC

    Nitrogen is obtained industrially by

    • Aburning coal
    • Bheating ammonium nitrite
    • Celectrolysis of water
    • Dfractional distillation of liquid air

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12. Question 32· Air· WAEC

    The percentage of oxygen in air can be found by passing a measured volume of air over

    • Aheated copper
    • Bcold water
    • Csodium chloride
    • Dsilica gel

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13. Question 33· Air· WAEC

    Water vapour in air can be detected by

    • Alime water turning milky
    • Banhydrous cobalt(II) chloride paper turning pink
    • Ca glowing splint relighting
    • Dlitmus turning red

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14. Question 34· Air· WAEC

    The most abundant gas in air is

    • Aoxygen
    • Bcarbon dioxide
    • Cnitrogen
    • Dargon

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15. Question 35· Air· WAEC

    Air is passed over heated copper turnings and the copper turns black. This is because

    • Anitrogen combines with the copper
    • Boxygen in the air forms copper(II) oxide
    • Cthe copper absorbs water vapour
    • Dcarbon(IV) oxide is deposited on it

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16. Question 36· Air· WAEC

    Approximately what percentage of dry air by volume is oxygen?

    • A21%
    • B78%
    • C1%
    • D0.03%

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17. Question 37· Air· WAEC

    Which noble gas is used in advertising signs because it glows red when electricity passes through it?

    • Aneon
    • Bhelium
    • Cargon
    • Dxenon

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18. Question 38· Air· WAEC

    The noble gas used in advertising signs because it glows red is

    • Akrypton
    • Bargon
    • Chelium
    • Dneon

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19. Question 39· Air· WAEC

    The percentage of oxygen in air by volume is about

    • A0.03%
    • B78%
    • C21%
    • D1%

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20. Question 40· Air· WAEC

    Air is regarded as a mixture rather than a compound because

    • Aits composition varies from place to place
    • Bit is colourless
    • Cit contains oxygen
    • Dit can be liquefied

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