JAMB and WAEC Chemistry questions: Energy changes

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

1. Question 1· 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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2. Question 2· Energy changes· JAMB

   Forming new chemical bonds

   • Ahas no energy change
   • Babsorbs energy
   • Cneeds a catalyst
   • Dreleases energy

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3. Question 3· Energy changes· JAMB

   The heat of neutralisation of a strong acid by a strong base is about

   • A−57 kJ per mole of water formed
   • B+57 kJ per mole
   • C−890 kJ per mole
   • D0 kJ per mole

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4. Question 4· Energy changes· JAMB

   When ammonium chloride dissolves in water, the temperature of the water

   • Arises and then falls
   • Brises
   • Cstays the same
   • Dfalls

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5. Question 5· Energy changes· JAMB

   Bond energy is the energy

   • Aof one electron
   • Breleased when a solid melts
   • Cneeded to break one mole of a particular bond
   • Dneeded to boil one mole of a liquid

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6. Question 6· 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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7. Question 7· Energy changes· JAMB

   In which of the following changes does entropy increase?

   • Aa gas being compressed
   • Bsteam condensing
   • Cice melting
   • Dwater freezing

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8. Question 8· Energy changes· JAMB

   The enthalpy of combustion of methane is −890 kJ/mol. How much heat is released when 8 g of methane burns? [C = 12, H = 1]

   • A445 kJ
   • B890 kJ
   • C1,780 kJ
   • D111 kJ

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9. Question 9· Energy changes· JAMB

   Enthalpy changes that cannot be measured directly can be calculated using

   • ABoyle's law
   • BHess's law
   • CGraham's law
   • DFaraday's law

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10. Question 10· Energy changes· JAMB

    Hess's law states that the enthalpy change of a reaction

    • Adepends on the catalyst
    • Bis the same whatever route is taken
    • Cis always negative
    • Ddepends on the rate of reaction

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11. Question 11· 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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12. Question 12· 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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13. Question 13· Energy changes· WAEC

    A reaction in which heat is absorbed from the surroundings is

    • Areversible
    • Bexothermic
    • Ccatalytic
    • Dendothermic

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14. Question 14· 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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15. Question 15· Energy changes· WAEC

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

    • Aexothermic
    • Bneutralisation
    • Cendothermic
    • Dcombustion

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16. Question 16· 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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17. Question 17· Energy changes· JAMB

    On an energy profile diagram, adding a catalyst

    • Alowers the energy peak (activation energy)
    • Braises the energy of the products
    • Cchanges ΔH
    • Draises the energy peak

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18. Question 18· Energy changes· JAMB

    Breaking chemical bonds is

    • Aan endothermic process
    • Ban exothermic process
    • Cneither endothermic nor exothermic
    • Da nuclear process

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19. Question 19· Energy changes· JAMB

    Which of the following is an endothermic process?

    • Acombustion of petrol
    • Bphotosynthesis
    • Crespiration
    • Dneutralisation

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20. Question 20· Energy changes· JAMB

    The heat of combustion of a substance is the heat released when

    • Aone mole of it burns completely in oxygen
    • Bone gram of it melts
    • Cit dissolves in water
    • Dit is neutralised

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