Why does the temperature of the crystalline body remain constant during the melting process?

The energy that a crystalline body receives after it is heated to the melting temperature is spent on breaking the bonds between molecules in the crystal lattice, so the body temperature stops rising.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.