Question

When heat is constantly supplied by a burner to boiling water, then the temperature of water during vaporisation:

• A. First rises and then becomes constant
• B. Rises rapidly until steam is produced
• C. Does not rise at all
• D. Rises very slowly

Answer 1

The correct option is C Does not rise at all

The temperature remains constant during boiling of water even though heat is supplied constantly because all the heat energy provided is used up in changing the state of water from liquid to gaseous water vapour. Therefore all the heat energy provided increases the kinetic energy of the particles and temperature doesn't increase.