JAMB Physics questions: Change of state

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

1. Question 1· Change of state· JAMB

   Adding salt to ice

   • Alowers its melting point
   • Braises its melting point
   • Chas no effect on its melting point
   • Dturns it into steam

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   Explanation and discussion

2. Question 2· Change of state· JAMB

   Increasing the pressure on water

   • Aremoves its latent heat
   • Braises its boiling point
   • Cdoubles its volume
   • Dchanges its colour

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   Explanation and discussion

3. Question 3· Change of state· JAMB

   Wet clothes dry faster on a windy day because wind

   • Aadds water
   • Braises the boiling point
   • Cremoves the vapour and speeds up evaporation
   • Dcools the sun

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   Explanation and discussion

4. Question 4· Change of state· JAMB

   Evaporation causes cooling because

   • Aheat flows into the liquid
   • Bthe liquid absorbs cold from the air
   • Cthe liquid's mass increases
   • Dthe faster molecules escape, lowering the average kinetic energy of those left

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   Explanation and discussion

5. Question 5· Change of state· JAMB

   While a pure liquid is boiling, its temperature

   • Arises and falls
   • Brises steadily
   • Cfalls steadily
   • Dremains constant

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   Explanation and discussion

6. Question 6· Change of state· JAMB

   A pressure cooker cooks food faster because

   • Asteam is a poor conductor
   • Bit lowers the boiling point of water
   • Cit uses less water
   • Dthe increased pressure raises the boiling point of water

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   Explanation and discussion

7. Question 7· Change of state· JAMB

   The specific latent heat of fusion of a substance is the heat needed to

   • Araise 1 kg of it by 1 K
   • Bchange 1 kg of it from solid to liquid without a change of temperature
   • Cboil 1 kg of it
   • Dmelt any amount of it

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   Explanation and discussion

8. Question 8· Change of state· JAMB

   How much heat is given out when 0.2 kg of steam at 100 °C condenses to water at 100 °C? (L = 2.26 × 10⁶ J/kg)

   • A4.52 × 10⁵ J
   • B2.26 × 10⁵ J
   • C1.13 × 10⁷ J
   • D4.52 × 10⁶ J

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   Explanation and discussion

9. Question 9· Change of state· JAMB

   Find the heat needed to melt 2 kg of ice at 0 °C. (Specific latent heat of fusion = 3.36 × 10⁵ J/kg)

   • A6.72 × 10⁵ J
   • B3.36 × 10⁵ J
   • C1.68 × 10⁵ J
   • D6.72 × 10⁶ J

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   Explanation and discussion

10. Question 10· Change of state· JAMB

    How much heat changes 0.1 kg of water at 100 °C into steam? [specific latent heat of vaporisation = 2.26 × 10⁶ J/kg]

    • A2.26 × 10⁷ J
    • B2.26 × 10⁵ J
    • C2.26 × 10⁴ J
    • D4.2 × 10⁴ J

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    Explanation and discussion

11. Question 11· Change of state· JAMB

    How much heat is needed to change 0.1 kg of water at 100 °C into steam at 100 °C? (Latent heat of vaporisation = 2.26 × 10⁶ J/kg)

    • A2.26 × 10⁶ J
    • B2.26 × 10⁵ J
    • C2.26 × 10⁴ J
    • D4.2 × 10⁴ J

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    Explanation and discussion

12. Question 12· Change of state· JAMB

    At the top of a high mountain, water boils at a temperature

    • Ahigher than 100 °C
    • Blower than 100 °C
    • Cof exactly 100 °C
    • Dof 0 °C

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    Explanation and discussion