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प्रश्न
Why does the temperature of a substance remain constant during its melting point or boiling point?
उत्तर
When a substance melts, it absorbs heat for the conversion of the solid state into a liquid state. As we continue heating, the heat supplied is used up in converting the solid state into a liquid state by overcoming the forces of attraction between the particles and there is no change in temperature till the whole solid is converted into liquid. This heat absorbed by the solid which does not result in an increase in temperature is called the latent heat of fusion. When a liquid is heated, it starts converting into vapours.
Further heat given to the liquid is used in changing the state and there is no increase in the temperature till the liquid starts boiling. This heat is known as the latent heat of vaporisation. Hence, the temperature of a substance remains constant at its melting point or boiling point until all the substance melts or boils.
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संबंधित प्रश्न
Differentiate between melting point and boiling point, giving atleast one example of each.
Describe an experiment to demonstrate that water absorbs heat during boiling at a constant temperature.
A pressure cooker is based on the principle that boiling point of water increases with the ______.
The boiling point of water is defined as ______.
By the process of Heating of water, ______ is obtained.
Choose the correct statement of the following
The boiling points of diethyl ether, acetone and n-butyl alcohol are 35°C, 56°C and 118°C respectively. Which one of the following correctly represents their boiling points in kelvin scale?
____________ is the change of solid state directly to vapour state without going through the ____________ state.
Assertion (A): Burning of a candle is considered a physical as well as chemical change.
Reason (R): Melting of wax is a physical change melted wax turns into vapours and then bums which is a chemical change.
Assertion (A): No-new substance is formed when water is heated to get steam.
Reason (R): Conversion of water into steam is a physical change.
