Multiple choice

What is the main difference between boiling and evaporation?

  1. Boiling causes reduction in volume of liquid while evaporation does not.

  2. Changing of boiling liquid into vapour can be seen but evaporation cannot be seen.

  3. Boiling causes a change in the state of water while evaporation does not.

  4. Evaporation can take place at any temperature while boiling cannot.

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For a given pressure, there is a temperature above which liquid cannot exist in liquid form. This temperature is called boiling point. At this pressure and at this temperature, if liquid is heated up, the temperature will not rise and heat is used only to convert the liquid into its vapour. The process of conversion of liquid into its vapour at this temperature is called boiling. Depending upon the pressure, there are many boiling temperature for a liquid. If the pressure is lowered the boiling temperature is lowered. For a given pressure, if the temperature of the liquid is below its boiling point, still the liquid is converted into vapour by the surface of the liquid. This process is called evaporation. Evaporation can take place at any temperature below the boiling temperature where as boiling can take place only at boiling temperature.

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