Endothermic you can see this by putting a thermometer in a glass or warm water, adding an ice cube and watching the temperature go down as the ice melts
Even though the substance is absorbing thermal energy, the temperature will remain the same during the change of state until ALL the amount of the substance has changed then the temperature will begin to rise again
As you know, milk is not a pure substance. Hope i helped ya!
The average atomic mass of Neon would simply be the sum of the weighted average of each isotope. That is:
average atomic mass = 0.905 * 20 + 0.003 * 21 + 0.092 * 22
average atomic mass = 20.187 amu