Question

Why does the temperature remain constant during boiling though heat is constantly supplied

Answer 1

The temperature remains constant during the boiling of water even though heat is supplied continuously. This is because, the heat supplied is absorbed by the water particles and this heat increases their kinetic energy.

Answer 2

The temperature remains constant during the change of state of a solid to liquid, because the eneegy which is actually supplied to change the state is used up in breaking down the force of attraction between the particles of solid.

$\textbf{Then when temperature will rise of heat is supplied continuously ? }$

Tempertaure will only increase when the whole solid get melted to form liquid, then the heat supplied will start to break the force of attraction between the particles of liquid.