Temperature of a body is due to the heat gained or loss. During a phase change, the atoms or molecules of a substance are undergoing change is temperature due to which no temperature change is observed during phase change. The heat in the transition phase is used to break bonds and the change in temperature is felt when kinetic energy change is complete. During transition, the average kinetic energy of the molecules remains unchanged and hence during a phase change a temperature do not changes until unless the phase change is completed.
