WAEC Chemistry questions

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

1. Question 161· Energy changes· WAEC

   Which of these processes is endothermic?

   • Aburning of wood
   • Bmelting of ice
   • Crusting of iron
   • Drespiration

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2. Question 162· Energy changes· WAEC

   The heat change when one mole of water is formed from the neutralisation of an acid by a base is the heat of

   • Acombustion
   • Bneutralisation
   • Cformation
   • Dsolution

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3. Question 163· Energy changes· WAEC

   For C + O₂ → CO₂, ΔH = −394 kJ/mol. How much heat is released when 6 g of carbon burns completely? [C = 12]

   • A197 kJ
   • B394 kJ
   • C788 kJ
   • D65.7 kJ

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4. Question 164· Environmental pollution· WAEC

   Gas flaring at oil fields in the Niger Delta adds mainly which greenhouse gas to the atmosphere?

   • Aoxygen
   • Bcarbon(IV) oxide
   • Cnitrogen
   • Dargon

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5. Question 165· Environmental pollution· WAEC

   Carbon monoxide is poisonous because it

   • Ais acidic
   • Bcombines with haemoglobin and stops it carrying oxygen
   • Chas a strong smell
   • Ddissolves in the blood as an acid

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6. Question 166· Environmental pollution· WAEC

   Domestic generators should not be run indoors because they release

   • Aoxygen
   • Bcarbon monoxide, which can kill silently
   • Cnitrogen only
   • Dwater vapour only

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7. Question 167· Environmental pollution· WAEC

   Gas flaring in the Niger Delta releases

   • Aclean water
   • Bpure oxygen
   • Ccarbon dioxide and pollutants into the atmosphere
   • Dfertiliser

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8. Question 168· Environmental pollution· WAEC

   The main cause of water pollution in many Nigerian rivers is

   • Aphotosynthesis
   • Brainfall
   • Cevaporation
   • Ddumping of untreated sewage and refuse

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9. Question 169· Environmental pollution· WAEC

   Chlorofluorocarbons (CFCs) damage which layer of the upper atmosphere?

   • Awater vapour
   • Bozone
   • Ccarbon(IV) oxide
   • Dargon

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10. Question 170· Environmental pollution· WAEC

    Carbon(II) oxide is poisonous because it

    • Adestroys lung tissue
    • Bdissolves in blood to form an acid
    • Ccombines with haemoglobin and stops it carrying oxygen
    • Dblocks the nose

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11. Question 171· Environmental pollution· WAEC

    Which gas is mainly responsible for the greenhouse effect?

    • Acarbon(IV) oxide
    • Bnitrogen
    • Coxygen
    • Dargon

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12. Question 172· Environmental pollution· WAEC

    Acid rain damages buildings made of limestone because the acid

    • Areacts with calcium trioxocarbonate(IV)
    • Bfreezes in the stone
    • Cdissolves the cement only
    • Dadds water to the stone

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13. Question 173· Environmental pollution· WAEC

    Which of the following gases contributes to acid rain?

    • AArgon
    • BNitrogen
    • COxygen
    • DSulphur dioxide

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14. Question 174· Environmental pollution· WAEC

    Acid rain is caused mainly by

    • Aozone
    • Bcarbon monoxide
    • Cmethane
    • Dsulphur dioxide and oxides of nitrogen

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15. Question 175· Environmental pollution· WAEC

    Chlorofluorocarbons (CFCs) damage the environment by

    • Acausing hard water
    • Bdepleting the ozone layer
    • Cforming rust
    • Dfertilising soil

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16. Question 176· Environmental pollution· WAEC

    Noise pollution can best be reduced by

    • Ausing silencers on generators and vehicles
    • Bburning refuse
    • Cplanting crops near roads
    • Dusing more loudspeakers

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17. Question 177· Environmental pollution· WAEC

    Non-biodegradable wastes such as plastics are best managed by

    • Aburning in the open
    • Brecycling
    • Cdumping in rivers
    • Dburying in farmland

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18. Question 178· Environmental pollution· WAEC

    Acid rain is mainly caused by

    • Alead compounds
    • Bcarbon(II) oxide only
    • Coxides of sulphur and nitrogen
    • Dhydrogen gas

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19. Question 179· Kinetic theory of matter and gas laws· WAEC

    The change of a gas directly to a solid is called

    • Adeposition
    • Bsublimation
    • Cevaporation
    • Dmelting

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20. Question 180· Kinetic theory of matter and gas laws· WAEC

    A gas occupies 120 cm³ at 1 atm. What volume does it occupy at 3 atm at constant temperature?

    • A360 cm³
    • B40 cm³
    • C120 cm³
    • D20 cm³

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    Explanation and discussion