JAMB and WAEC Chemistry questions: Chemical equilibrium

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

1. Question 21· Chemical equilibrium· JAMB

   For 2SO₂ + O₂ ⇌ 2SO₃ (ΔH negative), the yield of SO₃ increases when

   • Apressure is raised and temperature lowered
   • Bpressure is lowered
   • Ctemperature is raised
   • DSO₃ is added

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   Explanation and discussion

2. Question 22· Chemical equilibrium· WAEC

   Heating blue hydrated copper(II) tetraoxosulphate(VI) turns it white; adding water turns it blue again. This shows that the change is

   • Aa combustion
   • Birreversible
   • Ca physical change only
   • Dreversible

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3. Question 23· Chemical equilibrium· JAMB

   For CaCO₃(s) ⇌ CaO(s) + CO₂(g) in a closed vessel, continuously removing the carbon(IV) oxide will

   • Ashift the equilibrium to the left
   • Bshift the equilibrium to the right
   • Chave no effect
   • Dstop the decomposition

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4. Question 24· Chemical equilibrium· WAEC

   Dynamic equilibrium means

   • Aonly reactants remain
   • Bthe reaction has stopped
   • Conly products remain
   • Dforward and backward reactions continue at equal rates

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5. Question 25· Chemical equilibrium· WAEC

   Le Chatelier's principle states that when a system at equilibrium is disturbed, it

   • Agoes to completion
   • Bstops reacting
   • Cshifts so as to oppose the change
   • Dreleases all its energy

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6. Question 26· Chemical equilibrium· JAMB

   For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), increasing the pressure shifts the equilibrium

   • Ato the right
   • Bto the left
   • Cin neither direction
   • Dto stop the reaction

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7. Question 27· Chemical equilibrium· WAEC

   A reaction that can proceed in both the forward and backward directions is

   • Areversible
   • Birreversible
   • Cexothermic only
   • Da combustion

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8. Question 28· Chemical equilibrium· WAEC

   A catalyst added to a system at equilibrium

   • Ashifts the equilibrium to the right
   • Bspeeds up both forward and backward reactions equally
   • Cincreases yield
   • Dstops the reaction

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9. Question 29· Chemical equilibrium· JAMB

   For N₂O₄ ⇌ 2NO₂ (ΔH positive), raising the temperature

   • Astops the reaction
   • Bshifts it to the left
   • Chas no effect
   • Dshifts the equilibrium to the right

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10. Question 30· Chemical equilibrium· WAEC

    For N₂ + 3H₂ ⇌ 2NH₃ (ΔH negative), the yield of ammonia increases if

    • Atemperature is increased
    • Bpressure is increased
    • Cammonia is added
    • Da catalyst is removed

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11. Question 31· Chemical equilibrium· WAEC

    Adding a catalyst to a system at equilibrium

    • Amakes equilibrium reached faster without changing its position
    • Bincreases the yield of products
    • Cshifts the equilibrium to the right
    • Dshifts the equilibrium to the left

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12. Question 32· Chemical equilibrium· JAMB

    Le Chatelier's principle states that when a system at equilibrium is disturbed, the system

    • Aalways moves to the right
    • Bstops reacting
    • Cshifts so as to oppose the disturbance
    • Dalways moves to the left

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13. Question 33· Chemical equilibrium· JAMB

    The equilibrium constant for N₂O₄(g) ⇌ 2NO₂(g) is

    • AK = [NO₂]/[N₂O₄]
    • BK = [N₂O₄]/[NO₂]²
    • CK = 2[NO₂]/[N₂O₄]
    • DK = [NO₂]²/[N₂O₄]

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14. Question 34· Chemical equilibrium· WAEC

    For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), increasing the pressure

    • Ahas no effect on the equilibrium
    • Bshifts the equilibrium to the left
    • Cshifts the equilibrium to the right
    • Dstops the reaction

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15. Question 35· Chemical equilibrium· JAMB

    For 2NO₂(g) ⇌ N₂O₄(g), increasing the pressure

    • Ashifts the equilibrium to the left
    • Bshifts the equilibrium to the right
    • Chas no effect
    • Ddecomposes N₂O₄

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16. Question 36· Chemical equilibrium· JAMB

    In the Haber process, ammonia is removed from the equilibrium mixture by

    • Aburning it
    • Bdissolving it in oil
    • Ccooling, so that it liquefies
    • Dpassing it over iron

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17. Question 37· Chemical equilibrium· JAMB

    The equilibrium constant Kc of a reaction changes only when the

    • Atemperature changes
    • Bpressure changes
    • Cconcentration changes
    • Da catalyst is added

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    Explanation and discussion