Question

why does the temperature remain unchanged ,until the entire solid changes into liquid, even if continue to heat the solid​

Answer 1

As a solid is heated, its temperature increases as the molecules move faster. During the phase change, when solid melts into liquid, its temperature remains constant as the heat energy is stored as potential energy. ... Finally, impurities will change the melting point and the boiling point of compounds.

plzz mrk me

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.