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Why does the temperature of a substance remain constant during its melting point or boiling point ?

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The temperature of a substance remains constant during melting and boiling points till the completion of melting and boiling. It is because substance makes use of latent heat of fusion to overcome force of attraction between particles of solid to change into liquid during melting and latent heat of vaporisation to overcome force of attraction between particles of liquid to change into vapours during boiling.
Therefore, temperature remains constant.

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Updated on:21/07/2023
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  • Question 1 - Select One

    The temperature of the substance remains constant when it is melting and boiling though some quantity of heat is supplied. What happens to this energy?

    AIt is dissipated as sound energy
    BIt is consumed to increase the energy of the molecules
    CIt is used to change the state of the substance
    DIt is still an unsolved problem in science.
  • Question 1 - Select One

    A given substance of mass 'm' is in solid state at certain temperature. Arrange the following steps in proper sequence to calculate the total heat energy required to just convert the substance completely into gaseous state.
    (A) Note down the specific latent heat of vapor ization of the substance and calculate the heat supplied to convert from liquid to gaseous state using the formula.
    (B) Note down the melting point of the substance and calculate the heat supplied to increase the temperature of the solid to its melting point.
    (C ) Note down the boiling point of the substance and calculate the heat supplied to increase the temperature of the substance from melting point to its boiling point.
    (D) Add all the heat energies, it gives the resultant heat supplied to the solid to just convert it into gaseous state.
    (E) Note down the specific latent heat of fusion of the substance and calculate the heat supplied to convert the substance from solid state to liquid state.

    AB D E C A
    BA C E D B
    CA B C D E
    DB E C A D
  • Question 1 - Select One

    A ginven substance of mass 'm' is in solid state at certain temperature. Arrange the following steps in proper sequence to calcualte the total heat energy required to just convert the substance completely into gaseous state.
    (a). Note down the specific latent heat of vaporization of the substance and calculate the heat supplied to convert from liquid to gaseous state using the formula.
    (b) Note down the melting point of the substance and calculate the heat supplied to increase the temperature of the solid to its melting point.
    (c) Note down the boiling point of the substance and calculate the heat supplied to increase the temperature of the substance from melting point to its boiling point.
    (d). Add all the heat energies, it gives the resultant hea supplied to the solid to just convert it into gaseous state.
    (e) Note down the specific latent heat of fusion of the substance and calculate the heat supplied to convert the substance from solid state to liquid state.

    Ab d e c a
    Ba c e d b
    Ca b c d e
    Db e c a d

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