Hello!
The property that is being demonstrated when Janice was given a mixture of alcohol and water and her teacher told her that she could use temperature to separate these compounds is boiling.
The boiling point is the temperature when a substance goes from liquid state to gas state. If two liquid substances with different boiling points are in a mixture, they can be separated by heating one of them to its boiling point and condensing the gas in another container in a process called distillation. The difference in boiling points of alcohols (usually lower than water) and water allows to separate them in a mixture.
Have a nice day!