Since there is no "new" chemicals made during this process, it is considered a physical change. Distillation is a process of separating dissolved solids or liquids with different boiling points without chemically changing anything.
Color change, formation if a new substance or altering molecular structure are all general signs of chemical change.
Therefore, the last answer choice looks like the best answer.
Calculating the mass number for an atom requires that we know the atomic number and the number of protons in the atom’s nucleus. The mass number then gives us the average weight of atoms of a given element. However, as long as the number of protons equals the number of neutrons, the values balance out and we always obtain a whole number for the mass number.
