A physicsl property is the property that can be measured without changing what you are measuring. Melting and Boiling points are physical properties because you do not change the object (i.e water) when you melt ice it turns to water and if you boiled water it turns into water vapour and it can be turned again into water if cooled. Therefore it shows physical property.
Because you can physically see the object melting when it comes to the melting point. The objects texture, color, temperature, shape, and state of matter (solid, liquid, gas) are possibly changing. Especially the bolded changes are happening.
