If a solid piece of naphthalene is heated and remains at 80°c until it is completely melted, you know that 80ºc is the

The solid piece of naphthalene when heated is observed to melt after it attains the temperature of 80° C and then this 80° C is called as it melting point. After 80° C naphthalene will start to melt and get transformed into liquid state. Also if this naphthalene is allowed to cool down after 80° C it will be the freezing point of naphthalene.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.