Unlike most chemical changes, most physical changes are easily reversed. When Adrian's teacher dissolves some sugar in a beaker of water, the process involves a physical change. Adrian is asked to recover just the sugar in the solution. How can Adrian do this?

By heating the solution

Explanation:

Physical changes and chemical changes are the two types of changes that a substance undergoes. Physical change does not alter the substance's chemical composition, hence, can be easily reversed. There is also no new product formed. This is contrary to the occurrences of a chemical change, which cannot be reversed after a new product has been formed.

A physical change is what occurs when Adrian's teacher dissolves some sugar in a beaker of water to form a sugar solution. This change does not involve any new product formation, hence, can be reversed. The sugar can be derived back from the solution by HEATING THE SOLUTION. The water (solvent) will evaporate and the sugar (solute) will precipitate.

not clear

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.